nti-evolutionist Ashby Camp has penned a critique of these "29 Evidences of Macroevolution," which can be found posted at TrueOrigin. Camp's critique is well-written, very thorough, and quite lengthy (the criticism is longer than the original article). Although I intend to address Camp's concerns in totality, currently I can only devote a limited amount of time to this effort. In the meantime, this partial response will suffice. I would like to thank Camp for his congenial criticism. It has given me the impetus to rework and expand the "29 Evidences," and the result is a more comprehensive, clearer, and stronger article.
My response has been two-fold. First, I have incorporated new material into the original essay that specifically addresses many of Camp's points, and thus much of his response is now superfluous. Second, in the following sections I rebut the more egregious errors found in Camp's criticism, especially ones that would interrupt the flow and thrust of the original article if they were included there. In the following response, Camp's words are indented in grey boxes, set apart from mine. Material that Camp has quoted in his criticism is also in the grey boxes, surrounded by quotes, and followed by the pertinent external reference.
Mr. Camp's critique is error-ridden in various ways, and is primarily characterized by:
The repeated use of these errors and others by Camp will be abundantly clear in the following rebuttal.
Since the time I wrote this reply, Mr. Camp has responded to this in a shorter article entitled "Camp answers Theobald." For the most part his response warrants no further comment, since most of the ground has already been covered either here or in the "29 Evidences." The elements which I felt deserve some mention are included here enclosed in green boxes.
Ashby Camp writes:
The alleged prediction and fulfillment are:
- If universal common ancestry is true, then all organisms will have one or more traits in common.
- All organisms have one or more traits in common.
Although Camp is most likely simply trying to paraphrase the point succinctly, he distorts the intent in doing so. The prediction is more specific than the above. To quote from the original prediction 1:
"Some of the macroscopic properties that characterize all of life are (1) replication, (2) information flow in continuity of kind, (3) catalysis, and (4) energy utilization (metabolism) .... all living species today should necessarily have ... inherited the structures that perform these functions. The genealogical relatedness of all life predicts that organisms should be very similar in the particular mechanisms and structures that execute these basic life processes." (emphasis added)
Which traits should be in common was and is expressly stated - the structures and mechanisms that perform the four basic life functions.
Unless one inserts an additional premise imposing a limit on the degree to which descendants can vary (which would require specification of a mechanism of descent), the claim of common ancestry does not require that all of the descendants share one or more traits. There is no logical reason why completely novel organisms could not arise in one or more lineages. Absent specification of a mechanism of descent, which Dr. Theobald purposefully avoids, there is no way to tether the traits of the descendants to those of the common ancestor.
In fact, there are limits on the degree to which descendants can vary. The constraint of gradualism is inherent in the theory of universal common descent - a point made explicitly in the original article. To quote from the introduction:
"... macroevolution is proposed to occur on a geological timescale and in a gradual manner .... Gradualness concerns genetically probable organismic changes between two consecutive generations, i.e. those changes that are within the range of normal variation observed within modern populations."
Elsewhere in his criticism (e.g., footnote 6), Camp bemoans the article's indifference to mechanism in explaining the evidence for common descent. Throughout the article, it is assumed that the fundamentals of biology (such as genetics, molecular biology, and developmental biology) are correct, especially those not directly dealing with the origin and evolution of biological adaptations. In creation-evolution debates this is not especially controversial; nearly all anti-evolutionists, including those who believe in special creation, also make this assumption. Though gradualism is not formally a mechanism of evolution (like natural selection or Lamarckism could be), gradualism does indeed put severe constraints on possible macroevolutionary phenomena, and it also constrains any possible mechanisms. Thus, Camp is incorrect when he says:
... universal common ancestry is compatible with all mechanisms of common descent, including divine direction. So if God chose to have a reptile give birth to a bird, for example, that would be consistent with an "amechanistic" argument for universal common ancestry.
A modern reptile giving birth to a modern bird is not gradual; it is saltation, since such changes between two consecutive generations are not genetically probable - they are not "within the range of normal variation observed within modern populations." This is not to say that God could not have created species independently and miraculously, yet gradually. While there currently is absolutely no scientific evidence for such an idea, gradual Divine direction of evolution is indeed consistent and compatible with common descent. In footnote 1, Camp paradoxically criticizes the constraint of gradualism:
In restricting the mechanism of macroevolution to observable degrees of genetic variation, Dr. Theobald lets in the back door the very debate about mechanism that he tossed out the front. He thereby assumes the burden of proving that accumulated observable variation can account for universal common ancestry. Since he makes no attempt to meet that burden but rather repeatedly disavows the relevance of any particular mechanism of modification, I assume he did not intend to specify accumulated observable variation as the mechanism of macroevolution, despite what his definitions may suggest.
As stated earlier, though gradualism is not a mechanism, it does indeed constrain possible explanatory mechanisms. Common descent is not concerned with exactly how adaptive change has happened, but whether it has happened and whether it is consistent with normal observed genealogical processes. Camp is wrong to say that the sufficiency of "accumulated observable variation" to account for universal common descent is left unaddressed. This requirement was and is explicitly considered in Part 5, "Change and Mutability," specifically in predictions 22, 23, 24, 28, and 29.
Camp has replied:
Rather than acknowledge that he overstated his case, Dr. Theobald ignores his contradictory statements and blames me for not knowing that he really meant to restrict the explanatory mechanisms to gradual ones. If that was his intent, he should not have claimed that he was arguing for common ancestry "independent of any explanatory mechanism." He was trying to have his cake and eat it too.
The statement that "the evidence and the conclusion [of common descent] are independent of any explanatory mechanism" was made on the very last page of the article. By placing it there, I assumed that the reader had in fact read the introduction and the rest of the article. Perhaps this assumption is unwarranted in Camp's case? At first, I was at a loss for understanding how Mr. Camp could so blatantly misrepresent the stance on mechanism put forth in the "29 Evidences." However, now it is clear Mr. Camp himself wrongly assumes that "any" is equivalent to "all." Saying that common descent is independent of any explanatory mechanism is not the same as saying that common descent is independent of all possible explanatory mechanisms (see definitions 1a, 2a, 2c, and 3b for any in the Merriam-Webster Dictionary, or the first two definitions of any in the Cambridge International Dictionary of English). Regardless, the gradualistic restriction of explanatory mechanisms is and was explicitly made numerous times throughout the "29 Evidences" (e.g. all of Part 3 is devoted to the direct consequences of this concept - note the quote at the heading). The concept of gradualism and the resulting constraints pervade the article. Indeed, Camp is to be blamed for not knowing a basic and explicit element of an argument which he is criticizing. Must every definition and concept be re-explained in every paragraph? Camp has provided us with yet another classic example of an anti-evolutionist pulling a comment out of context and interpreting it in opposition to the author's intent, with complete disregard for other pertinent, explicit, and clarifying statements.
Camp quotes the anti-evolutionist Walter ReMine to attack the evolutionary prediction of biological universals:
"First, evolution does not predict that life would arise precisely once on this planet. If there were two or more unrelated systems of life, then evolutionary theory would effortlessly accommodate that situation." (Remine 1993, p. 92-93)
Camp disavows this point in footnote 3, but still saw it fit to include it. ReMine's point is a red herring; the theory of universal common descent is the theory being considered, not multiple origins. If we were to establish that life had arisen more than once, universal common descent would be falsified, and thus evolutionary theory would not "effortlessly accommodate that situation."
Camp continues with ReMine's words:
"Second, even if life originated precisely once, then evolutionary theory would still not predict biologic universals. Shortly after life's origin, nothing prevented life from branching and leading separate lineages to higher life forms entirely lacking the known biologic universals.
Third, evolutionary loss and replacement processes could prevent biologic universals. If one organism is a distant ancestor to another, then nothing in evolution predicts the two must share similarities. If evolution were true, then distant ancestors and descendants (as well as sister groups) can be totally different." (Remine 1993, p. 92-93)
Here Camp again dismisses the fundamentals of biology and the constraint of gradualism. Common descent does predict specific biological universals, since any significant change (any "loss and replacement processes") in the structures that perform the four basic life functions would result in nonviable organisms; these structures cannot be lost nor can they be replaced (although they can be expounded upon). Once life attained these specific structures (by whatever process), they were essentially frozen. Gradualism constrains life from "branching and leading separate lineages to higher life forms entirely lacking the known biologic universals." Of course "distant ancestors and descendants ... can be totally different" - totally different except in the structures that perform the four fundamental functions of life.
Common descent does not predict that these structures must be identical, just that the similarity must be statistically significant, and that there must be viable intermediates between the variations. For instance, because the genetic code is degenerate, common descent does not predict an identical genetic code in all organisms. However, all known genetic codes are extremely similar, with an extremely high degree of statistical significance. In fact, common descent does not require that all organisms even have a genetic code. If life evolved from something that lacked a genetic code, then there must have been a series of organisms with transitional codes, beginning with no code at all. It is at least possible that such organisms could still be alive today. But if common descent is true, then the genetic codes of these organisms would be less complex versions of the modern genetic code and would retain statistically significant similarity to the modern universal genetic code. This is a testable prediction, in principle.
That said, the main important point of "prediction 1" is this - we can make very strong a posteriori predictions about biological universals by combining common descent with what is known. As a scientific analogy, Newton's Theory of Universal Gravitation does not predict planets, nor does it predict the present trajectories of planets. But given the known measured trajectory of an existing planet, we can use Newton's theory to predict what the trajectory will be in the future and what it must have been in the past, and these predictions can be confirmed or falsified. Likewise, given the fact that we now know that all organisms studied to date, including bacteria and birds, have a very similar glycolysis metabolic pathway (or genetic code), we can use common descent to predict that all undiscovered or unexamined organisms that fit between bacteria and birds in the standard phylogenetic tree will also have a similar glycolysis metabolic pathway (or genetic code). Because of common descent, we predict this even though this prediction is not functionally necessary - many other equivalent glycolysis pathways or genetic codes could function equally well. Because of common descent, we know that certain types of organisms will be extremely similar in the biological universals before we actually go and check the organisms to see what their structures really look like. Thus, Hunter is incorrect when Camp quotes him saying:
"Consider how evolutionists would react if there were in fact multiple codes in nature. What if plants, animals, and bacteria all had different codes? Such a finding would not falsify evolution; rather, it would be incorporated into the theory ... " (Hunter 2001, p. 38)
First, common descent does predict that the genetic codes should be similar a priori. Hunter is speculating about how evolutionists would have reacted in a hypothetical historical scenario in which we did not find highly similar codes between organisms. In reality, we can never know how biologists would have reacted to that, since that hypothetical scenario did not happen. What is known, however, is that the scientists who cracked the genetic code in the 1950's and 1960's worked under the assumption that the code was universal or nearly so (Judson 1996, p. 280-281). These scientists, which included Francis Crick, Sydney Brenner, George Gamow, and several others, all made this assumption and justified it based upon evolutionary reasoning, even in the complete absence of any experimental evidence. In fact, this assumption was instrumental in their success in solving the code. For instance, in 1957, nearly ten years before the genetic code was finally solved, Sydney Brenner published an influential paper in which he concluded that all overlapping triplet codes were impossible if the code was universal (Brenner 1957). This paper was widely considered a landmark work, since many researchers were leaning towards an overlapping code. Of course, it turned out that Brenner was correct about the nature of the true code. In 1961, five years before the code was deciphered, Crick and others also concluded that the code was (1) a triplet code, (2) non-overlapping, and (3) that the code is read from a fixed starting point (i.e. the "start" codon) (Crick et al. 1961). These conclusions were explicitly based on the assumption that the code was essentially the same in tobacco, humans, and bacteria, though there was no empirical support for this assumption. These conclusions turned out to be correct. In fact, in 1963 - three years before the code was finally solved - Hinegardner and Engelberg published a paper in Science specifically explaining why the code must be universal (or nearly so) if universal common descent were true, since most mutations in the code would likely be lethal to all living things. Note, Hinegardner and Engelberg did allow for some variation in the genetic code, and predicted how such variation should be distributed if found:
"... if different codes do exist they should be associated with major taxonomic groups such as phyla or kingdoms that have their roots far in the past." (Hinegardner and Engelberg 1963)
Their evolutionary prediction was correct, since the minor variations in the standard genetic code are indeed associated with major taxonomic groups (vertebrates vs. plants vs. single-celled ciliates, etc.).
Second, we now know from experimental research that many plants, many animals, and many bacteria all have extremely similar genetic codes. There is no known biological reason, aside from common descent, for why the genetic codes of different species should be similar. Any new discovery of a plant, animal, or bacteria with a radically different genetic code would be a highly unexpected result if common descent is true, and thus such a discovery would be a strong falsification.
Camp continues with Hunter's quote:
"There is nothing wrong with a theory that is comfortable with different outcomes, but there is something wrong when one of those outcomes is then claimed as supporting evidence. If a theory can predict both A and not-A, then neither A nor not-A can be used as evidence for the theory. When it comes to the genetic code, evolution can accommodate a range of findings, but it cannot then use one of those findings as supporting evidence." (Hunter 2001, p. 38.)
Hunter's logic concerning "A and not-A" is strictly correct, but it is misapplied (it is logically valid but unsound because one of the premises is false). In this case, evolution does not predict "both A and not-A" - it predicts "both A and B." Hunter equivocates by misidentifying "A and not-A" with a range of predicted outcomes. A range of outcomes ("A and B") does not necessarily encompass all possible outcomes ("A and not-A"). If a theory predicts both A and B, then either A or B can be used as evidence for the theory. All scientific theories predict a range of outcomes. For example, Newtonian physics predicts that projectiles will follow elliptical paths, parabolic paths, or linear paths, contingent upon the relevant conditions. Newtonian physics thus predicts A, B, and C, and any of A, B, or C can be used as evidence for Newtonian physics. This point is important, since Camp uses this same argument again, incorrectly, in his conclusion. Hunter's claim that "there is something wrong when one of those [different] outcomes is then claimed as supporting evidence" is clearly false as a blanket statement about scientific theories. To rewrite Hunter's incorrect statement: when it comes to the genetic code, evolution predicts a range of findings, and it can use any of those findings as supporting evidence. That's how science works.
Camp further obfuscates the prediction of biological universals by introducing hypotheses concerning the origin of the universal ancestor. He writes:
The fact that some leading evolutionists believe early life forms were biochemically distinct from modern forms confirms that evolution does not predict biologic universals. Robert Shapiro, for example, entertains the possibility of finding living relics of an original protein-based life form that lacked DNA and RNA. (Shapiro, 293-295.) Likewise, A. G. Cairns-Smith thinks that descendants of ancient crystalline clay organisms may be all around us. He states: "Evolution did not start with the organic molecules that have now become universal to life: indeed I doubt whether the first organisms, even the first evolved organisms, had any organic molecules in them at all." (Cairns-Smith, 107.)
First, exactly how the universal ancestor originated and evolved is not within the realm of common descent; common descent concerns all evolution and descent from the last common ancestor to the present. Secondly, and most importantly, these speculative hypotheses have no influence upon certain predictions of universals, such as the genetic code. The genetic code is a mechanism to translate nucleic acid information (DNA and/or RNA) into protein. Shapiro's original life form lacked DNA and RNA - it did not have a genetic code. Cairns-Smith's crystalline clay organisms had neither protein nor nucleic acid - thus neither did they have a genetic code. The universality of the genetic code was proposed based upon two facts: all known life carries genetic information in nucleic acids, and all known life performs metabolic functions with proteins. All known life thus has a genetic code. If all known life is also united by common descent, it must also be united by a universal genetic code. As recounted above, this was the exact reasoning of Francis Crick, Sydney Brenner, George Gamow, and Marshall Nirenberg when they were cracking the genetic code. Camp, and other anti-evolutionists like ReMine, can carp and criticize - yet the fact remains that real evolutionary biologists, doing hard science, made predictions and got phenomenal results based upon common descent and the deduction of biological universals.
On the other hand, ReMine argues that biologic universals are a prediction of his message theory of creation, which "says all life was constructed to look like the unified work of a single designer." (ReMine, 94.) So evolution does not predict the unity of living things, but at least one theory of creation does. Of course, the biochemical similarity of living things fits easily within a creation framework.
Of course biochemical similarity fits easily in a "creation framework." Anything can fit in the creation framework. This is precisely why present anti-evolutionary creationist theories are unscientific; they are not open to falsification. They are not even real theories or hypotheses. If there were no biochemical similarity, would that be inconsistent with the "creation framework"? ReMine's "message" hypothesis is close to being scientifically valid, but it is much too vague to be tested. What does a "unified work" look like? How would the biological world look if it were a "divided work"? Can ReMine quantify "appearance of unity"? Would independent researchers, perhaps from different cultures and countries, deduce the same predictions from this "message hypothesis"? Surely not - how something "looks" in terms of unity is subjective; it is not an objective property of life. How are we to distinguish between a single designer and multiple designers? Does Microsoft Word or an iMac or a Nissan Pathfinder look like the result of a single designer or multiple designers? A more fundamental problem is that ReMine's "message" hypothesis is not mutually exclusive with common descent, though he and Camp both seem to think that it is. Many world religions consider the existence of physical laws, such as the theory of universal gravitation, to be evidence that the universe is the unified work of a single Designer. In principle, couldn't a single designer have used evolution to make all of life look like a unified work? Of course; ReMine's conjecture and common descent could both be true.
Camp continues his discussion of how well he believes that creationism can explain biochemical similarities by quoting this fine piece of "scientific" creationist reasoning from Duane Gish:
"A creationist would also expect many biochemical similarities in all living organisms. We all drink the same water, breathe the same air, and eat the same food. Supposing, on the other hand, God had made plants with a certain type of amino acids, sugars, purines, pyrimidines, etc.; then made animals with a different type of amino acids, sugars, purines, pyrimidines, etc.; and, finally, made man with a third type of amino acids, sugars, etc. What could we eat? We couldn't eat plants; we couldn't eat animals; all we could eat would be each other! Obviously, that wouldn't work. All the key molecules in plants, animals, and man had to be the same. The metabolism of plants, animals, and man, based on the same biochemical principles, had to be similar, and therefore key metabolic pathways would employ similar macromolecules, modified to fit the particular internal environment of the organism or cell in which it must function." (Gish, 277.)
Both Gish and Camp obviously feel that God is extremely limited in ingenuity. Gish's contention is ridiculous; why couldn't God have created plants with one certain type of amino acids and animals with another type, and simply given animals the enzymes that metabolize plant amino acids? Wouldn't that be clever design? Obviously, that would work, and all the key molecules in plants, animals, and man did not have to be the same. Now, I am not stating that God should have made things this way, but I am certainly questioning the naive theological assumption made by Gish and Camp that God was incapable of creating things this way.
Camp ends his criticism of Prediction 1 with this strawman:
The claim that all organisms have one or more traits in common is true in the sense that all living things necessarily have the traits by which life is defined, but that is simply a tautology - living things all have the traits of living things.
As at the beginning, Camp's paraphrase is incorrect. The above claim is not the prediction of biological universals; the prediction is that structures which perform the basic functions that characterize life should be similar. Living things have the functions of living things (a tautology), but because all things are related by heredity (i.e. common descent), living things also should have similar structures and mechanisms that perform these basic functions (a deduction from common descent). It is possible that living things could all have the basic functions that characterize life while also having very different, chemically and structurally unrelated mechanisms that perform these basic functions. The prediction of biological universals is, therefore, not tautologous. And, as a deduction of common descent, the prediction of biological universals is testable, confirmable, and falsifiable. Furthermore, this prediction has been confirmed and has not been falsified. Like any good scientific theory, the possibility exists that it may be falsified in the future by the acquisition of new data, though this is highly unlikely since all other evidence confirms the validity of common descent.
Camp's argument is simply that descent by modification from a common ancestor does not predict a nested hierarchy. Camp is just plain incorrect here; all genealogical processes produce nested hierarchies. Think of your own family tree - your grandparents might have several kids, each of those kids (your aunts, uncles, and parents) have their own families, each of the children in those families (like you) may have their own children and even your children can have their own families. Each family is nested within another family, which in turn is nested within another family, and so on. Camp attempts to explain himself in his refusal to accept this basic concept:
Common descent can explain or accommodate nested hierarchy ... but it does not predict it. There are mechanisms of descent from a common ancestor that would yield a different pattern. If common descent can yield either nested hierarchy or something else, then the presence of nested hierarchy does not count as evidence of common descent.
Camp claims that different patterns can result from common descent - it would be nice if he could give us an example. I infer that the reason he does not give us examples is because they do not exist. If Camp means that "randomness" is a pattern (stretching the term "pattern"), then, yes, under certain conditions common descent predicts that some characters of species will be random with respect to each other. However, as has been discussed already, most theories in science predict multiple outcomes contingent upon the relevant conditions. This is not a problem for any scientific theory. Camp's last statement above is clearly false; it is the same error discussed above in Hunter's "A and not-A" claim. Common descent can predict two different outcomes and it can still use either of those outcomes as supporting evidence.
Camp has since replied to this criticism:
... the claim that the hypothesis of universal common ancestry makes a falsifiable prediction that organisms will exhibit a pattern of nested hierarchy is incorrect. Indeed, Dr. Theobald acknowledged in both prediction 2 and the response to my critique that Lamarck's organic progression would yield a non-nested pattern of organisms. ... since Lamarck's organic progression (to pick one example) admittedly does not predict a nested hierarchy, a nested hierarchy is not evidence of common descent via Lamarck's organic progression. Therefore, it is not evidence of common descent regardless of "whether Darwinism, Lamarckism, or something else is the true mechanism of evolutionary change," which is the proposition being argued by Dr. Theobald.
Although Camp still does not provide us with an example of a non-nested pattern generated by common descent, he does think that Lamarck's organic progression would predict a non-nested pattern. Camp is correct. However, Camp does not understand the difference between Lamarckism (or inheritance of acquired characters), which is an evolutionary mechanism, and the Lamarckian organic progression, which is not an evolutionary mechanism but is a descriptive macroevolutionary theory. Of course Lamarck's organic progression does not predict a nested hierarchy - it is mutually exclusive with common descent. Lamarck's organic progression is a competing theory, and common descent and the organic progression cannot both be true. However, Lamarckian evolution (by inheritance of acquired characters) could, in principle, be a mechanism of change that drives common descent by gradual modification. Camp's discussion here just proves my point. If we observed a pattern like that predicted by the organic progression, it would strongly indicate that common descent was false and that the organic progression was true. In other words, Lamarck's organic progression predicts a non-nested pattern - if we observed that pattern, it would falsify common descent.
Camp then tries to support this misunderstanding with another quote from Hunter:
"It has been known since Aristotle that species tend to cluster in a hierarchical pattern, and in the eighteenth century Linnaeus saw it as a reflection of the Creator's divine plan. Obviously this pattern does not force one to embrace evolution." (Hunter 2001, p. 107.)
It seems clear to me that Hunter is implying that since the hierarchical pattern of species was known before the theory of common descent was proposed, then the hierarchical pattern cannot be used as evidence for common descent. According to such logic, Newton's theory of gravity is also suspect. It has been known since long before Aristotle that apples fall to the ground when dropped. Some people before Newton, such as Aristotle, thought that apples were attracted to the ground because they were primarily made of the "earth" element. Obviously this pattern (falling) does not force one to embrace the inverse square law. It should be clear that the fact that people were wrong about physical explanations in the past is not an argument against modern scientific theories.
However, in private correspondence, Hunter has vociferously objected to my interpretation of his comments given above. Hunter claims that he was simply pointing out that alternative "theories" can explain the observed nested hierarchy. For such a point to be valid, the alternate "theories" would need to be of equal scientific rank as the theory of common descent. To my knowledge, neither Aristotle nor Linnaeus proposed any hypothesis concerning the nested hierarchy, and neither of them ever made any testable predictions based on any hypothesis proposed to explain the nested hierarchy. In contrast, common descent has certainly been proposed as a hypothesis which predicts the nested hierarchy, and many predictions based upon universal common descent have been made and tested by evolutionary biologists within the past 140 years. As such, the philosophical and theological ideas of Aristotle and Linnaeus do not compete scientifically with the formal hypothesis of common descent. Furthermore, there is no reason why the theological significance Linnaeus attached to the nested hierarchy should exclude common descent; it is of course possible for a theist to see the theory of common descent, and the hierarchy which it predicts, as a reflection of the Creator's divine plan, much as Sir Isaac Newton saw his laws of motion, and the ellipses and parabolas which they predict, as evidence of the Creator's hand in our universe.
Hunter's quote continues:
"Also, Darwin's law of natural selection does not predict this pattern. He had to devise a special explanation - his principle of divergence - to fit this striking pattern into his overall theory." (Hunter 2001, p. 108.)
Branching or divergence of species (i.e. speciation) is an inherent part of common descent. Darwin's principle of divergence of character was his particular explanation for speciation. However, Darwin's specific principle is unnecessary for common descent to produce a nested hierarchy - all that is necessary is speciation, regardless of cause. Most importantly, the views of this 19th century naturalist, though interesting historically, are of no consequence whatsoever for the validity of modern evolutionary theories. Camp appears to be confused about whether common descent must include branching of species or not:
Even a mechanism of descent that includes branching events does not ensure a nested pattern.
If multiple species evolved from a common ancestor, how could they have arisen without branching? "One" turning into "two" necessarily includes a branching event. Divergence (i.e. speciation) is thus inherent in the concept of common descent. Again, think about a family tree. Genealogies branch and diverge. The very essence of common descent is that all species are related like individuals in a genealogy. Camp quotes ReMine in support of this misunderstanding:
"The pattern of descent depends on the extent that evolved characters are later lost. Suppose losses are significant, and characters are replaced at a high rate. Then there is no reason to expect a nested pattern. Descendants could be totally different from their distant ancestors and sister groups, with little or no semblance of nested similarities linking them." (ReMine, 343.)
ReMine is partially correct, yet errs large. If rates of evolution are fast, then the cladistic information indeed can be lost given enough time, since the cladistic information would be essentially randomized. The faster the rate, the less time needed to obliterate the information in biological characters about the historical branching pattern of evolution. Slowly evolving characters let us see farther back into time; faster evolving characters restrict that view to more recent events. This is a difficulty that biologists must deal with in reality. But, importantly, it is also a prediction of common descent. Given a certain rate of evolution, we can determine how long it will take for cladistic information to be lost. ReMine forgets that "rate of evolution" vs. "time since divergence" is relative; thus, in some time frame we will always be able to observe a nested hierarchy if common descent is true. Furthermore, we know empirically that background mutation rates vary by orders of magnitude from locus to locus in the genomes of species. This fact means that hierarchies should be observed at many biological levels, since some genes evolve faster or slower than others.
ReMine thinks that since there are certain conditions under which a prediction of our theory will not be observed, then observing the prediction is not a confirmation of our theory. If this were true, we could never confirm any scientific hypothesis, not just common descent, since there are always certain conditions under which we will be unable to observe some consequence of a theory.
All ReMine is saying is that, under certain conditions, common descent predicts that hierarchical structure will be randomized. It is unclear why this is a problematic feature of the theory of common descent. Under certain conditions, Newtonian theory predicts that objects will not follow elliptical orbits, but that they will follow parabolas. Are we thus supposed to conclude that observing the elliptical orbits of the planets cannot be used as evidence for Newtonian theory? No, and the same is true for common descent. This is the same error as Hunter's "A and not-A" discussion addressed above. ReMine simply does not understand how the scientific method works.
Camp has since contested my criticism of ReMine's arguments:
This is a mischaracterization of Remine's position. ReMine is not claiming that fulfillment of a theory's falsifiable prediction (e.g., the mutual attraction of two masses decreases in proportion to the square of the distance between them) is nullified by an inability to test the prediction under certain circumstances (e.g., where the attraction is predictably below measurable limits).
The phrase "inability to test" is misstated. We can always test - it is only after testing that we compare the results to our predictions. If we assume that something is untestable beforehand then we are assuming the truth of our theory - we are not testing it. What Camp must mean here, to make sense scientifically, is "inability to observe a given prediction." In fact, this is exactly what ReMine is claiming - there is no mischaracterization. ReMine claims that fulfillment of a theory's falsifiable prediction (e.g., the observation of a "nested pattern") is nullified by an inability to observe the prediction under certain circumstances (e.g., when the hierarchy is predictably randomized because "losses are significant, and characters are replaced at a high rate").
Rather, he [ReMine] is claiming that nested hierarchy is not a falsifiable prediction of common ancestry because the theory includes without restriction processes that work against that pattern. Those processes can be invoked in any blend to account for any non-nested pattern that is observed.
Well, ReMine is also making this claim. However, ReMine and Camp are both incorrect in stating that it is problematic to invoke processes that "work against" a prediction of a theory. With Newton's theory of gravity, there are plenty of things that can be invoked to account for anomalous results. For instance, naively, feathers and bowling balls supposedly fall at the same rate. If dropped from the same height, they should hit the ground at the same time - that is, if the theory is correct. But we all know that is untrue. Feathers fall more slowly, and we invoke another process, air resistance, to explain why feathers fall in a way not predicted by the theory. But there is more - electrons and protons do not follow the gravitational inverse square law either. We invoke electric charge to explain that. Refrigerator magnets also "violate" the theory of gravity. Here we invoke a process, magnetism, that works against the patterns predicted by Newton's theory. In some cases, like three- or four-body problems, we admit that Newton's theory fails to give an exact answer. When we are only considering two objects, like the Sun and the earth, we can solve the equations of motion exactly. But add just one more element, like the moon, and the equations are impossible to solve (though the answers can sometimes be approximated). In other cases, as with the orbit of Mercury, we drop Newton's theory altogether and invoke relativistic effects. In reality (something that anti-evolutionists like ReMine try to avoid thinking about), all scientific explanations are complex, except in the most unrealistic, contrived situations found in carefully controlled laboratory environments. In a lab, we can remove the air from a container and watch a bowling ball and a feather fall at the same rate. As stated elsewhere here, processes cannot "be invoked in any blend to account for any [...] pattern." Complex explanations are required to be reasonable and to conform to empirically observed processes - they are not invoked "without restriction." All the processes that ReMine and Camp complain about have been empirically observed, and they are testable propositions. Evolutionary biology, thus, is no more problematic than any other scientific discipline. To repeat, ReMine simply does not understand how the scientific method works.
Mr. Camp uses an additional quote from ReMine with the intent to criticize common descent and the prediction of nested hierarchies:
"Evolution does not predict a hierarchical pattern. Simple processes of loss, replacement, anagenesis, transposition, unmasking, or multiple biogenesis would prohibit such a pattern. Since hierarchical patterns (such as cladograms or phenograms) are not predicted by evolution they are not evidence for evolution." (ReMine 1993, p. 444.)
However, Camp has misquoted ReMine. ReMine is not specifically referring to common descent in this passage; he is writing about evolution in general. ReMine keeps common descent and evolution distinct (as he should). For instance, multiple biogenesis is not common descent. This is clear from the very next sentence that follows the quote above:
"Life's hierarchical pattern (as displayed in cladograms and phenograms) is too indirect to establish even the special case of common descent." (ReMine 1993, p. 444.)
ReMine considers common descent to be a special case of evolution, which of course it is. But his point that common descent is not a necessary case of evolution is senseless. It is analogous to criticizing the inverse square law because it could have been an inverse cube law or an inverse factorial law. He might as well say - "Gravity does not predict elliptical orbits. Since elliptical orbits are not predicted by gravity then it is not evidence for gravity." Which he could have followed with - "Elliptical orbits (as displayed by planets and projectiles) are too indirect to establish even the special case of the inverse square law." Despite ReMine's protestations, nested hierarchies are measurable features of organisms - their presence or absence can be quantified and evaluated with statistics. The prediction of a nested hierarchy follows directly from the hypothesis of common descent.
Furthermore, ReMine is incorrect in claiming that "loss, replacement, anagenesis, transposition, unmasking, or multiple biogenesis would prohibit" a hierarchical pattern. Of course, multiple biogenesis could, but we are not considering multiple biogenesis, we are considering universal common descent. The other processes mentioned all create hierarchical patterns, since character losses, replacements, anagenetic changes, transpositions, and reversals (unmasking events) are all inherited by descendants of an ancestor. For example, if all apes are descendants from a long-tailed primate common ancestor that lost its tail, then all apes will lack tails, while other primates will have tails. If an ape acquired a gene by transposition into the germ-line, then all descendants of that ape would inherit that transposition. If some non-ape primate then had a short tail replace its long tail, then all descendants of the short-tailed primate would inherit that short tail. The result is a nested hierarchy.
_____________________________________________________ | primates | | ________________ _____________ ______________ | | | apes | | long tails | | short tails | | | | ______ ______ | | | | | | | || no ||trans.|| | | | | | | ||trans.|| || | | | | | | | ______ ______ | _____________ ______________ | | | | | | ________________ | | | _____________________________________________________
These "simple processes" are the very types of things that make nested hierarchies.
Since this was written, Camp has replied:
There are various ways in which existing organisms could descend from a common ancestor and not exhibit a nested hierarchy. Anagenesis, loss of characters, replacement of characters, transposition of characters, atavism (masking and unmasking), and convergence all work against a hierarchical pattern, and the bare hypothesis of universal common ancestry says nothing about the rate or prevalence of those processes. They can be invoked in whatever blend is necessary to explain whatever pattern is found. Therefore, the claim that the hypothesis of universal common ancestry makes a falsifiable prediction that organisms will exhibit a pattern of nested hierarchy is incorrect.
Notice how Camp avoids all of the points which were made against his argument. Camp does not provide an example of a non-nested pattern. He reiterates the claim that various processes destroy a nested pattern, when in fact those very processes create a nested pattern. These processes cannot be "invoked in whatever blend is necessary to explain whatever pattern is found." Yes, "bare" common descent may not state anything specifically about these processes, but universal common descent is constrained by gradualism, as has been explained many times over. We know empirically the maximum rates of anagenesis, character loss, and character replacement - such processes can be used in scientific explanations, of course, but there are limits on what rates can be used. This was already addressed specifically in predictions 22, 23, 24, 28, and 29. Furthermore, we also know that convergence happens (it is a prediction of natural selection and is observed regularly in the wild and in the lab). However, true structural convergence, in which distantly related taxa perform the same functions with the same underlying structures, is rare relative to divergence. In fact, when considering DNA sequence evolution, we can calculate very precisely what rates of convergence are reasonable and what rates are highly unlikely.
Camp then goes on to quote another confused anti-evolutionist, Michael Denton, in support of his assertion that common descent does not predict a nested hierarchy:
"In the final analysis the hierarchic pattern is nothing like the straightforward witness for organic evolution that is commonly assumed. There are facets of the hierarchy which do not flow naturally from any sort of random undirected evolutionary process. If the hierarchy suggests any model of nature it is typology and not evolution. How much easier it would be to argue the case for evolution if all nature's divisions were blurred and indistinct, if the systema naturalae was largely made up of overlapping classes indicative of sequence and continuity." (Denton 1986, 136-137.)
In evolution, "sequence and continuity" are truly only displayed in the time dimension. Horizontal slices of time may hint at continuity, especially between closely related species - but branching and divergence from a common ancestor predicts nested hierarchies at any given time, not a continuum. Denton just doesn't understand what common descent is (or didn't at the time he wrote this passage). Common descent is the hypothesis that all species are strictly genealogically related. That means that species should be organizable into a family tree. It is very easy to see that a family tree gives nested hierarchies at any given single point in time. Someone, like Denton, who doesn't understand even the most fundamental evolutionary concepts really has no business criticizing evolutionary theory. If all of nature were "blurred and indistinct," if the "systema naturalae was largely made up of overlapping classes," this would not indicate common descent, it would indicate something like Lamarck's organic progression or the medieval view of the "great chain of being." Camp has replied to these comments:
Next, Dr. Theobald chides me for quoting "another confused anti-evolutionist," Michael Denton. As an aside, I find it fascinating that, according to Dr. Theobald, Denton "doesn't understand even the most fundamental evolutionary concepts." It is fascinating because one often hears that nothing in biology makes sense except in light of evolution. And yet, Denton, being ignorant of the most fundamental evolutionary concepts, managed to earn a Ph.D. in developmental biology (in addition to an M.D.), to write or co-author over seventy articles in professional journals, and to work for decades as a genetics researcher. Apparently knowledge of evolution is irrelevant to a career in science.
I am confident that Michael Denton has contributed greatly to scientific knowledge in his area of expertise. Yet, Camp's logic here is wanting. Someone can have a successful scientific career, especially in an applied field, without understanding the theory behind the science they practice. Plenty of people drive cars and fly in planes who understand not a thing about how cars and planes work. Most people who consider themselves "computer literate" don't really understand how computers do their thing at the most basic level (and I count myself among them). I can program in Basic, Perl, and some C++ and Java - but that doesn't mean I understand how to make a functional silicon computer chip. Even silicon chip designers often know extremely little quantum mechanics, even though electromagnetic theory and quantum mechanics ultimately explain the behavior of all electronic devices. Likewise, someone can be a good medical doctor without understanding why the drugs they prescribe work effectively, and someone can do plenty of good biological research without understanding evolutionary biology. Nevertheless, nothing in computing makes sense except in the light of microchip technology, nothing in microchip technology makes sense except in the light of quantum mechanics, nothing in the automobile industry makes sense except in the light of mechanics and thermodynamics, nothing in aviation makes sense except in the light of aerodynamics, nothing in medicine makes sense except in the light of biochemistry, and nothing in biology makes sense except in the light of evolution.
It is not to the benefit of Camp's argument that he uses quotes from Denton's book, Evolution: A Theory in Crisis. This book is so ridden with errors, false "facts," illogic, and uninformed dialectical rubbish that it is hard to understand how Camp could find any use in it. As one of a myriad of examples, immediately preceding the paragraph quoted by Camp above, Denton writes:
"There is another stringent condition which must be satisfied if a hierarchic pattern is to result as the end product of an evolutionary process: no ancestral or transitional forms can be permitted to survive." (Denton 1986, p. 136, emphasis in the orginal).
This is obviously false and nicely illustrates the wanton ignorance concerning basic evolutionary concepts displayed in this book. This passage is, additionally, directly pertinent to the present discussion of nested hierarchies. Denton immediately follows the above statement with:
"This can be seen by examining the tree diagram above on page 135. If any of the ancestors X, Y and Z, or if any of the hypothetical transitional connecting species stationed on the main branches of the tree, had survived and had therefore to be included in the classification scheme, the distinctness of the divisions would be blurred by intermediate or partially inclusive classes and what remained of the hierarchic pattern would be highly disordered." (Denton 1986, p. 136)
The absurdity of these statements is evident when one includes the ancestors X, Y, and Z in Denton's nested hierarchy figure. All the ancestors (including a hypothetical transitional connecting species, W) fit in the existing nested hierarchy just fine, without blurring the distinctness of divisions or contributing disorder to the hierarchical pattern. If Denton could not even work out the simple evolutionary predictions based upon his very own figures and examples, it is no wonder that he thought that "the hierarchic pattern is nothing like the straightforward witness for organic evolution that is commonly assumed."
Dr. Theobald's disparaging comment notwithstanding, Denton's point about the nested hierarchy observed in nature has merit. The discreteness or discontinuity of the groupings does not flow naturally from a random, undirected evolutionary process. One must explain why the morphological space between the groups exists, as opposed to the divisions being blurred and indistinct. The point is not that evolutionists cannot explain it but that it is something that requires an explanation.
If that is the point then it is a moot one for our present discussion. All natural phenomena require an explanation, scientifically. Is there supposed to be something problematic about that? In fact, "discreteness or discontinuity of the groupings" does "flow naturally from a random, undirected evolutionary process." Extinction is an observable fact, both in the fossil record and in the present. Extinction is all that is needed to cause discontinuity (though other processes can also be involved). Extinction is also largely random and undirected.
Interestingly, it appears that Denton may have finally rectified his misunderstanding about nested hierarchies and common descent, since in his latest book he unconditionally assumes the validity of the nested hierarchy, common descent, and the "tree of life" (Denton 1998, pp. 265-298). For example, in the chapter entitled The Tree of Life from Nature's Destiny, Denton discusses the phylogeny of several closely related species (the primates) and directly contradicts his previous misstatements presented by Camp above:
"In the case of primate DNA, for example, all the sequences in the hemoglobin gene cluster in man, chimp, gorilla, gibbon, etc., can be interconverted via single base change steps to form a perfect evolutionary tree relating the higher primates together in a system that looks as natural as could be imagined. There is not the slightest indication of any discontinuity." (Denton 1998, p. 277)
This was written by the same man who scribed:
"Each class at a molecular level is unique, isolated and unlinked by intermediates. Thus, molecules, like fossils, have failed to provide the elusive intermediates so long sought by evolutionary theory." (Denton 1986, p. 290)
One wonders how Camp can feel justified in quoting Denton's past confusions about common descent. Camp has responded to this:
Dr. Theobald apparently misunderstands Denton's point in the quote, as he claims that Denton subsequently contradicted himself in opining that the hemoglobin gene cluster in primates was not discontinuous. Just because Denton believes there is no discontinuity requiring an explanation in that particular instance does not mean he denies there is discontinuity elsewhere. So Dr. Theobald's comment ("One wonders how Camp can feel justified in quoting Denton's past confusions about common descent") is misguided.
Contrary to Camp's later protestations, here Denton is not referring to primate DNA as an exception - he now sees it as an example of a generality of life. That is why Denton prefaces this case with "for example." One wonders if Camp has read Denton's new book.
At this point, Camp leaves science and enters into theological arguments:
The notion that the nested hierarchy of organisms is incompatible with creation is based, not on science, but on the unprovable theological assumption that if God created life he would do it in some other way. As biologist Leonard Brand explains:
The hierarchical arrangement of life illustrated in Fig. 9.6 has been used by Futuyma (1983) and others as evidence that life must have evolved. They believe that if life were created, the characteristics of different organisms would be arranged chaotically or in a continuum, not in the hierarchy of nested groups evident in nature. If we think of that concept as a hypothesis, how could it be tested? Actually, to state how a Creator would do things and then show that nature is or is not designed that way is an empty argument. Such conjecture depends on the unlikely assumption that we can decide what the Creator would be like and how he would function. (Brand, 155.)
In fact, no theological assumptions or arguments are made at all in the essay. The "29 Evidences" is not an argument against creation - it is the scientific argument for common descent, no more, no less. The evidence for common descent can only be evidence against creation if one believes the two are mutually incompatible. A belief that Divine creation and common descent are mutually exclusive alternatives is indeed a theological assumption, and it is one that Ashby Camp makes, not I. If Camp has independent evidence that a Creator has created life to result in a nested hierarchical classification, let him present that evidence. If the hypothesis that a Creator created in this manner is testable and falsifiable, let Ashby Camp tell us how. Personally, I agree with Brand when he says that "to state how a Creator would do things and then show that nature is or is not designed that way is an empty argument. Such conjecture depends on the unlikely assumption that we can decide what the Creator would be like and how he would function" (Brand 1997, p.155). Camp also concurs, as he says that predictions about how God would create are "based, not on science, but on the unprovable theological assumption that if God created life he would do it in some [specific] way." The creation hypothesis that a Creator created life with nested hierarchies is not scientific; as Brand and Camp note, it is untestable. It is highly ironic that Camp has tried to turn a fatal weakness of creationism into a weakness of the theory of common descent.
Throughout his criticism, indeed in every section, Camp relentlessly accuses me of making theological assumptions which I do not make. Frankly, I find this to be highly offensive, since in reality it is Ashby Camp who makes the theological assumptions and then projects his bias on me. I personally believe that an omnipotent, omniscient Creator could have created in any manner that he chose. For a theist, the pertinent question is not "what is an omnipotent Creator capable of?" but rather "how exactly did/does the Creator create?". The first question is purely theological, and as such is left unaddressed in the "29 Evidences"; in contrast, the second question is one that science can answer (given the assumption of a Creator).
The "29 Evidences" concerns scientific evidence only - that means only hypotheses which can be tested against hard empirical evidence, only hypotheses that can be either confirmed or falsified in principle. Unfortunately, Camp forwards numerous meaningless, untestable "creation hypotheses" throughout his critique, apparently under the self-deceiving illusion that they have some relevance to the present issue. However, in the quoted section above, Camp states outright that conjecture about how a Creator created is not scientific, because such conjecture cannot be tested and because we cannot know the Creator's intent in the first place. Thus, every alternative "creation hypothesis" that Camp proffers is scientifically meaningless by his own admission.
It may be that the nested hierarchy of living things simply is a reflection of divine orderliness. It also may be, as Walter ReMine suggests, that nested hierarchy is an integral part of a message woven by the Creator into the patterns of biology. (See, e.g., ReMine, 367-368, 465-467.) The point is that the hierarchical nature of life can be accommodated by creation theory as readily as by evolution. Accordingly, "[i]t is not evidence for or against either theory." (Brand, 155.)
Creation theory can, to my knowledge, accommodate any possible outcome and is therefore untestable, unfalsifiable, and unscientific. If Camp has an opposing view and has examples of observations that would falsify creation theory, let him present them. Common descent, on the other hand, cannot accommodate any outcome; common descent predicts observable nested hierarchies. If rates of evolution are extremely fast (or extremely slow), nested hierarchies will be observed only for very recently diverged taxa (or for very distantly related taxa). Fortunately, we observe a range of evolutionary rates in different characters and thus observe nested hierarchies at many levels in biology. It is worth pointing out here that it is in fact possible to have a "reciprocal" pattern from nested hierarchies. Mathematically, a nested hierarchy is the result of specific correlations between certain characters of organisms. When evolutionary rates are fast, the characters become randomly distributed with respect to one another, and the correlations are weakened. However, the characters could also be anti-correlated in theory - it is possible for them to be correlated in the opposite direction from what produces nested hierarchies. The observation of such an anti-correlated pattern would be highly inconsistent with common descent, regardless of evolutionary rates.
Camp concludes his criticism of this point with an attack on the very notion of cladistic classification:
Dr. Theobald's claim that "specially designed objects like buildings, furniture, cars, etc." cannot be classified in a nested hierarchy requires elaboration. In terms of mere classification, it is incorrect. Buildings and vehicles have both been used as examples of nesting (Ridley 1993, 52-54; Fastovsky and Weishampel, 51-53; Brand, 165-166).
Camp's assertion stems from a misunderstanding, one that is addressed in detail in the new version of the "29 Evidences" under prediction 2. Some authors have used more familiar objects for illustrating nested hierarchies; however, these are only for explanatory purposes and are not meant to be strict analogies. Of course buildings and cars can be arbitrarily sorted into nested hierarchies. The point is that they do not form natural nested hierarchies; they do not meet the mathematical requirements of nested hierarchies. Camp seems not to understand this point, in spite of the fact that one of his favorite anti-evolutionists explains it clearly:
"Any system of objects can be forcibly classified into a nested hierarchy. Some systems do not have to be forced, rather they display a nested pattern with clarity without having to be coerced. Life has such a pattern. There are no tetrapods that are not based on the vertebrate body plan. There are no amniotes that are not based on the tetrapod body plan. There are no mammals that are not also amniotes. These are the familiar examples, and many more can be given. They are powerful generalizations. Life is like nested Chinese boxes of subsets within subsets within subsets. Life is comprised of nested similarities. This significant pattern must be explained." (ReMine 1993, p. 344)
And common descent explains it.
Camp concludes this misunderstanding with a quote from a well-known evolutionary biologist, which only appears to support his point:
"Any set of objects, whether or not they originated in an evolutionary process, can be classified hierarchically. Chairs, for instance, are independently created; they are not generated by an evolutionary process: but any given list of chairs could be classified hierarchically, perhaps by dividing them first according to whether or not they were made of wood, then according to their colour, by date of manufacture, and so on. The fact that life can be classified hierarchically is not, in itself, an argument for evolution." (Ridley 1985, 8.)
Camp carefully and quite misleadingly omits the very next sentence:
"The argument for evolution comes from a particular property of the classificatory hierarchy, the kind of traits that define it." (Ridley 1985, 8.)
Ridley goes on to make a good qualitative argument for the uniqueness of genealogically generated nested hierarchies, of how life's nested hierarchy is not "forced." However, Ridley was of course unaware of the more rigorously defined mathematical differences between "pseudo"-hierarchies of things like cars, chairs, or buildings and the real hierarchies of organisms or languages, because the mathematics for examining cladistic hierarchical structure was first worked out six years later, in 1991. Outdated science is not an argument against modern theories. What would Camp think if I were arguing against the existence of X-rays and, in support of my position, quoted Lord Kelvin when he said, "X-rays will prove to be a hoax"?
Camp has since replied to this criticism of his argument given above:
I wrote that "[i]n terms of mere classification," the statement was incorrect. To back up the claim that such specially designed objects can indeed be classified in a nested hierarchy (regardless of whether they possess genuine hierarchical traits), I pointed out that they are often used as examples of nesting.
It is in that context that I quoted Ridley. The point was that "[a]ny set of objects, whether or not they originated in an evolutionary process, can be classified hierarchically" (emphasis supplied), not that all sets of objects possess bona fide hierarchical traits. I omitted Ridley's statement that life exhibits a genuine hierarchy because it was irrelevant to my point. So Dr. Theobald has quoted me out of context in accusing me of quoting out of context! He then builds on his confusion in suggesting that I intentionally sought to mislead people ("Camp carefully and quite misleadingly omits the very next sentence").
First, I never suggested that Camp intentionally sought to mislead people. I did claim that Camp "carefully" omitted an important part of Ridley's statements, and Camp has admitted to that. I also claimed that omitting that sentence is misleading, which it is. It makes it appear as if Ridley meant something different than what he intended. Whether Camp intentionally wrote that line to mislead people is something only Camp himself can know.
Second, I did not quote Camp out of context. I included Camp's sentence "In terms of mere classification, it is incorrect."
Third, it is now quite clear that Camp understands that there are important differences between artificial and "bona fide" nested hierarchies:
... I was not quoting Ridley to deny there is a difference between artificial and genuine hierarchies but only to support my contention that specially designed objects can be classified in a nested hierarchy ...
So what? That is a very trivial point; someone could artificially classify pennies as "square rabbits", too. It is of course valid to state that pennies cannot be classified as squares or rabbits, because pennies obviously do not satisfy the requirements of geometrical squares or biological animals. The comment that Camp was contesting was the first line of the following:
Real world examples that cannot be classified as [nested hierarchies] are elementary particles (which are described by quantum chromodynamics), the elements (whose organization is described by quantum mechanics and illustrated by the periodic table), the planets in our Solar System, books in a library, or specially designed objects like buildings, furniture, cars, etc. That certain organisms merely are similar to each other is not enough to support macroevolution; the nested classification pattern that satisfies the macroevolutionary process is very specific. ... Most existing species can be organized rather easily in a nested hierarchical classification. This is evident in the use of the Linnaean classification scheme. ... As a specific example (see Figure 1), plants can be classified as vascular and nonvascular (i.e. they have or lack xylem and phloem). Nested within the vascular group, there are two divisions, seed and non-seed plants. Further nested within the seed plants are two more groups, the angiosperms (which have enclosed, protected seeds) and the gymnosperms (having non-enclosed seeds). Within the angiosperm group are the monocotyledons and the dicotyledons. ... Few species are ever found that combine characteristics of different nested groupings.
Again, Mr. Camp has taken a quote out of context and used the resulting ambiguity to infuse it with a meaning contrary to its intent. When someone says "X cannot do Y," it does not necessarily mean that "it is impossible for X to do Y" - it can also mean that "it is impermissible for X to do Y" (see the definition of can in the Merriam-Webster dictionary). It is of course clear from the context in the above passage that can was used in the second sense, since the reasons why some objects have genuine hierarchical characteristics and others do not was explained.
In this light, it is quite curious that Camp made such a fuss over the fact that someone could artificially categorize certain non-hierarchical things in nested hierarchies. That was not the point made in Prediction 2 of the "29 Evidences" - so why include the Ridley quote to begin with? The point was simply that species form natural nested hierarchies, while chairs, books, the planets, the elements, and fundamental particles do not - and Camp evidently agrees. I suppose I made a mistake in assuming that Camp's arguments and supporting quotes were actually directed against the evidence for common descent?
Common descent predicts that independent determinations of phylogenetic histories should be similar. Once again, Camp denies that this is a prediction of common descent. However, this time, his basis for denial is that he thinks this prediction has been falsified, and since scientists do not toss out common descent, this must not be a prediction of common descent. Camp's error lies in his belief that this prediction has been falsified. Camp says:
The important point is that it is not a prediction of the hypothesis of common ancestry that phylogenies constructed from comparisons of biological molecules will match phylogenies constructed from comparisons of morphology. This is obvious from the fact molecular and morphological phylogenies often are inconsistent, and yet the hypothesis of common descent is not considered falsified. The discordant data are simply accommodated by the theory.
Camp is correct that often independently determined phylogenies are not exactly the same (i.e. they are incongruent). But in science, independent measurements of some value (such as a physical constant like the charge of the electron, the mass of the proton, or the speed of light) are never exact. There always exists some error in the measurement, and all independent measurements are incongruent to some extent. Of course, the true value of something is never known for certain - all we have are measurements that we hope approximate the true value. Scientifically, then, the important relevant questions are "When comparing two measurements, how much of a discrepancy does it take to be a problem?" and "How close must they be to be a strong confirmation?" Scientists answer these questions with probability and statistics. This issue is specifically addressed in the revised version of the "29 Evidences" under prediction 3. The upshot is that the degree to which even the most incongruent trees match is extraordinary. Penny and Hendy have done a detailed statistical analysis of the significance of similar phylogenetic trees, and here is their conclusion:
"Biologists seem to seek the 'The One Tree' and appear not to be satisfied by a range of options. However, there is no logical difficulty in having a range of trees. There are 34,459,425 possible trees for 11 taxa (Penny et al. 1982), and to reduce this to the order of 10-50 trees is analogous to an accuracy of measurement of approximately one part in 106." (Penny and Hendy 1986, p. 414)
For a more realistic universal phylogenetic tree with dozens of taxa including all known phyla, the accuracy is orders of magnitude smaller (better).
So Camp is incorrect on two counts. First, common descent does indeed predict that independently determined trees should be similar - if there really is a true genealogical tree of species, how could this not be the prediction? This is exactly why all the scientists that Camp quotes are concerned about incongruent trees. Second, the trees are stunningly similar - even the most incongruent ones. Incongruent trees are a "problem" in the sense that we biologists wish to attain perfection in our science, and incongruent trees are imperfect. Even so, the differences are just much too minor to falsify common descent; to the contrary, they confirm this prediction of common descent to a much higher degree than is found in any other scientific discipline.
Unfortunately, Camp's argument is fundamentally flawed at a much deeper level. Camp contradicts himself; in his eagerness to "disprove" common descent, Camp simultaneously argues for two opposing views. Camp states:
... molecular and morphological phylogenies often are inconsistent, and yet the hypothesis of common descent is not considered falsified. The discordant data are simply accommodated by the theory.
and follows with this a few paragraphs later:
The availability of such ad hoc adjustments for resolving incongruities makes the claim of falsifiability an illusion. Any result can be accommodated by the theory by revising one or more of the underlying assumptions.
Why is there any discordant data if any result can be changed at will with ad hoc revising of the assumptions? These statements are contradictory, and obviously both cannot be true. In fact, both are false.
Biologists cannot "adjust the assumptions" to give any desired result. Camp is making the slanderous claim that biologists unethically manipulate their data to result in a predetermined outcome. Here's a test: if Camp's malign accusation is true, he should be able to adjust the assumptions of a phylogenetic analysis to result in a tree of my choice. Using any molecular data of his choice, Camp should be able to generate a phylogenetic tree with a standard tree-building program (such as PAUP, Phylip, MacClade, etc.) that places chimps closest to fish, humans closest to birds, cows closest to insects, and bacteria closest to marsupials, specifically as shown below:
C F H B Cw I B M \/ \/ \ / \/ \ / \/ / \/ / / \ / / \ / / \/ / \ / V |
The truth is that Camp will be unable to meet this challenge. All scientists, including biologists, must deal with this annoying thing called "reality." Real data cannot be arbitrarily fit to any model with equal success. Even more importantly, scientists do not uncritically accept ad hoc assumptions. Valid assumptions must be reasonable and independently testable.
Mr. Camp has addressed this challenge:
Dr. Theobald's challenge to construct a molecular phylogeny to his specification ... misses the point. The point is that his specified molecular phylogeny would be compatible with the bare hypothesis of universal common ancestry.
In other words, Camp admits he is unable to meet the specified challenge. By doing so, Camp concedes that it is untrue that "Any result can be accommodated by the theory by revising one or more of the underlying assumptions" (emphasis added). As clearly evidenced by the exchange above, that was the point being discussed here - not that any "phylogeny would be compatible with the bare hypothesis of universal common ancestry." This last point, which Camp urges is the point, is silly. It is of course true in an extremely trivial sense - if we ignore all other relevant data and the requirements of common descent on our planet. But we cannot ignore this data, since the only way we can test the theory of common descent is with real evidence from our world. We test common descent in the real world, on this planet, with the organisms that we observe here - not with some fictional concoction from Camp's head. Theories are tested with specific data from specific cases - a basic scientific point that is completely lost on Camp. It is analogously true that a specified value of 6 x 10-7 m3 kg-1 s-2 for the universal Newtonian constant of gravitation would be compatible with the bare hypothesis of universal gravitation. But the true value is (approximately) 6.673 x 10-11 m3 kg-1 s-2, and the specified hypothetical value is massively inconsistent with all current measurements which have approximated this universal constant. Again, we test universal theories with specific data from independent measurements in the real world - a fundamental aspect of the scientific method with which Camp is clearly unacquainted.
The fact remains that the specified phylogeny given above is massively inconsistent with the morphological phylogeny and all known molecular phylogenies, and the specified phylogeny cannot be constructed with any known molecular sequences, regardless of how the assumptions are adjusted. This is exactly what one would predict if common descent is true, and this is precisely why common descent is a falsifiable hypothesis. My specified tree could be compatible with common descent in a different world - but in our world it is incompatible with common descent, and the real data do not support such a fictitious phylogeny.
In discussing incongruent phylogenies, Camp uses a favorite quote of "scientific" creationists by Christian Schwabe and Gregory Warr (Camp gets Schwabe's name wrong - it is not "Christopher"):
Two years earlier, Schwabe and Gregory Warr were equally blunt in their criticism of molecular phylogenies. They saw the field of molecular evolution as being mired in subjectivity driven by an a priori commitment to universal common ancestry. They wrote:
We believe that it is possible to draw up a list of basic rules that underlie existing molecular evolutionary models:
- All theories are monophyletic, meaning that they all start with the Urgene and the Urzelle which have given rise to all proteins and all species, respectively.
- Complexity evolves mainly through duplications and mutations in structural and control genes.
- Genes can mutate or remain stable, migrate laterally from species to species, spread through a population by mechanisms whose operation is not fully understood, evolve coordinately, splice, stay silent, and exist as pseudogenes.
- Ad hoc arguments can be invented (such as insect vectors or viruses) that can transport a gene into places where no monophyletic logic could otherwise explain its presence.
This liberal spread of rules, each of which can be observed in use by scientists, does not just sound facetious but also, in our opinion, robs monophyletic evolution of its vulnerability to disproof, and thereby its entitlement to the status of a scientific theory. The absolute, explicit and implicit, adherence to all the monophyletic principle and consequently the decision to interpret all observations in the light of this principle is the major cause of incongruities as well as for the invention of all the genetic sidestepping rules cited above. (Schwabe and Warr, 467.)
Camp quotes Schwabe and Warr without providing any hard evidence to back up their claims. Schwabe and Warr wrote these statements over 15 years ago, when we had only a tiny fraction of the presently known molecular sequences. Frankly, they are wrong. Just because a scientist makes an argument does not mean that his argument is correct. Just because it is published does not make it correct. Publication in peer-reviewed journals is only the first step of scientific peer-review. Schwabe and Warr stated their case, but the evidence acquired since has not supported their views. Science is weighed and measured with hard evidence and specific examples. Does Camp give any to support Schwabe and Warr's claims? No.
Let's examine Schwabe and Warr's claims. First, it is untrue that "All theories are monophyletic ...". The hypothesis of the universal common ancestry of species is not the same as universal common ancestry of proteins and/or genes. In fact, it is virtually certain that genes and proteins have arisen independently many times throughout evolutionary history. We know of many mechanisms for creating proteins and genes de novo. For instance, we have observed the evolution of a completely novel protein in bacteria by mutations which translate a gene in a new reading frame. The resulting protein has no similarity to the initial one (Ohno 1984). Second, increases in complexity due to gene duplications and mutations have been observed in the wild and the lab (Copley 2000; Futuyma 1998, p. 274; Lederberg and Lederberg 1952; Lee, Yoon et al. 1998; Ohno 1984; Okada et al. 1983; Orser and Lange 1994; Salamone et al. 2002). For example, Flavobacterium recently evolved the ability to metabolize the exclusively man-made chemical nylon as its sole carbon source. This ability required the duplication and mutation of genes for three different enzymes (Negoro et al. 1994; Ohno 1984; Okada et al. 1983). These results have also been duplicated in the lab (Prijambada et al. 1995). Some of these studies have demonstrated that new enzymes have evolved with increased specificity for their substrates (Salamone et al. 2002). This is not ad hoc nor is it "liberal" - it is factual. Third, we observe stochastic (random) mutation of genes regularly (which means we expect that often, simply due to chance, genes will not mutate), we regularly observe lateral transfer (Dowson et al. 1994; Ochman et al. 2000; Widdowson et al. 2000), we have observed genes spread through populations (yes, even when mechanisms are not well understood) (Raymond et al. 2001), we find silent genes, we find splicing genes (Hastings and Krainer 2001), we find pseudogenes (Mighell et al. 2000). We have observed genes evolve coordinately (Copley 2000; Negoro et al. 1994). Again, none of this is ad hoc, nor is it "liberal" it is factual. Fourth, countless times we have observed viral vectors insert genes where monophyly could not explain it (Hindmarsh and Leis 1999; Urnovitz and Murphy 1996). Neither is this ad hoc - it is factual. Finally, Schwabe and Warr state that biologists resorted to the "the invention of all the genetic sidestepping rules cited above" in order to explain their observations. That is absurd. Biologists did not "invent" these mechanisms; they were empirically discovered both in the wild and in the lab over the past few decades. Now, over fifteen years after Schwabe and Warr wrote these words, we have delineated these various processes in considerable detail, both mechanistically and structurally at the molecular level.
It is not ad hoc to explain observations with mechanisms that have been observed. It is not a "liberal spread of rules." It is, however, good scientific practice. In many, probably most, cases these proposed mechanisms are independently testable. For example, horizontal gene transfer by viral insertion into a host genome leaves easily recognizable tell-tale signs in the sequences surrounding the inserted gene. If a gene has been inserted by a viral vector, these tell-tale sequences should be there. In fact, it would be unjustified and ad hoc to be aware of all these observations over the past 50 years of various genetic mechanisms and to argue that they were not important in the past 3.5 billion years of evolutionary history. Camp, Schwabe, and Warr appear to be miffed that biology is complex, and that there are many ways for genes to be transmitted between organisms besides linear inheritance between generations. But this is real science, the real world, real biology - the real world is not simple, and biology is the most complex of sciences. Biological data demand complex explanations. Just because a scientific explanation is complex does not mean it is unfalsifiable. Very clear, unambiguous ways exist to falsify common descent, and demonstrating pervasive, highly incongruent phylogenies is one of them, in spite of these various mechanisms which could be used to explain relatively minor incongruencies. For more explanation, refer to prediction 3.
Furthermore, Schwabe and Warr grossly overstate the importance of known incongruent phylogenies. As addressed in prediction 3 and as illustrated by the Penny and Hendy comment above, incongruent data in phylogenetic analyses are much less problematic than incongruent data in other scientific fields, such as particle physics and gravity. As stated above, in reality the known incongruent trees are a "problem" only in the sense that we biologists wish to attain perfection in our science, and incongruent trees are imperfect.
Camp's fallacious appeal to authority falls apart upon even cursory inspection. It is yet another example of using outdated (and marginal) science in an attempt to bolster a flawed argument.
Camp even doubts that correspondence between molecular and morphological phylogenies is evidence for common descent:
Even if a morphological phylogeny was matched closely by multiple molecular phylogenies, that would not prove that the groups in question descended from a common ancestor. The molecular differences could be linked to the morphological differences for some other reason.
Though Camp's point is valid, it already has been addressed extensively in Prediction 3, Prediction 17, and Prediction 18 of the "29 Evidences." It is relatively simple to find genes or parts of genes (the molecular evidence) that are not functionally linked to morphology.
Camp goes on to quote Hunter concerning this point:
Hunter illustrates the point this way:
Penny obtained his trees by culling those that were most parsimonious - that is, he selected the trees that showed the least amount of evolutionary change to represent the history of life. The first problem is that Penny's method works perfectly fine on things we know did not come about via Darwinian evolution. For example, Penny's method would also claim that automobiles evolved from one another.
As pointed out above, Hunter is incorrect. Hunter makes the bold claim that "Penny's method would also claim that automobiles evolved from one another" in the absence of any evidence to support that claim. Automobiles might give a most parsimonious tree (though this is not assured), but even if they do, the resulting tree will be bunk. It will not satisfy the mathematical requirements for nested hierarchies, and the reasons are explained in Prediction 2. If Camp and Hunter think otherwise, they should determine a phylogenetic tree of cars, using standard phylogenetic programs, that has statistically significant high values of cladistic hierarchical structure. To really drive the point home, they could derive two trees independently, and then show that they match with statistical significance. If they are correct, they could easily prove their point - but in reality they will be unable to do so.
Camp continues with Hunter's quote:
Consider a group of vehicles, beginning with a small economy car and increasing in size to larger cars and to minivans and large-sized vans. One could quantify several aspects of the vehicle designs, such as tire size, steering mechanism, engine size, number of seats and so forth. Presupposing the evolutionary paradigm and searching for parsimonious relationships, we would find that most of the design measures suggest the same relationship. The smaller vehicles have smaller tires, manual steering, smaller engines, and fewer seats. The larger vehicles have larger tires, power steering, larger engines, and more seats. In other words, the groupings suggested by the different design measures (tire size, steering mechanism, engine size, etc.) tend to be similar. But of course, the family of automobiles did not evolve from one another via random mutations. The groupings of the design measures are a natural result of engineering and have nothing to do with Darwinian evolution. How then can Penny's results provide "strong support" for evolution? (Hunter, 40.)
Hunter's example is erroneous for another reason - he has obviously chosen characters that are not independent. This is a big "no-no" in cladistic analysis, and it is a rudimentary issue that is addressed early on in any introductory text on phylogenetic analysis. When using characters of organisms in a cladistic analysis, biologists attempt to use characters that are as functionally and developmentally independent of one another as possible. For instance, the size of an animal is only one character. Of course larger animals will in general have larger bodies, larger legs, and larger heads, just as in Hunter's example larger cars have larger tires, larger engines, etc. To be valid, "largeness" cannot be counted more than once. The very obvious solution, which is regularly used by biologists, is to measure the relative sizes of different characters. For instance, having a femur/tibia ratio of 3 is a different character from having a femur/tibia ratio of 1/2, regardless of the overall length of the bones. Biologists know that they must normalize for size, and instead they concentrate on structural details. Hunter's example is a classic strawman.
Penny's analysis (Penny et al. 1982) used five genes, four of which are functionally independent; thus, the result that trees made from several different independent genes match with statistical significance is indeed extremely strong support for common descent. For Hunter's analogy to be valid, he would have to claim that phylogenetic trees made only with cars' steering wheels will match phylogenetic trees made only with cars' tires and trees made only with cars' headlights and trees made only with cars' engines and trees made only with cars' transmissions. Obviously, such a claim would be false, since cars with similar tires (e.g. similar width/diameter ratio, manufacturers, tread, color, materials, etc.) do not generally also have similar engines (e.g. similar manufacturer, injection systems, cylinder arrangement, orientation, etc.), or headlights (e.g. similar shape, brightness, manufacturer, bulb type, position, number, etc.), or transmissions, or steering wheels.
Camp believes that "it would not be surprising from a creation perspective to find that biochemical similarities increase in relation to other similarities of the creatures being compared," and he quotes anti-evolutionists Duane Gish and Leonard Brand in support:
"We know, for instance, that man is more similar to a chimpanzee than he is to a bat; that he is more similar to either a chimpanzee or a bat than he is to a crocodile or a flea. Man, chimpanzee, and the bat are mammals. The creationist would expect, therefore, that his protein, DNA, and RNA molecules, those macromolecules that are among the most important molecules in metabolism, would be more similar to those of the chimpanzee and to those of the bat than to those of the crocodile or the flea." (Gish, 277-278.)
"Anatomy is not independent of biochemistry. Creatures similar anatomically are likely to be similar physiologically. Those similar in physiology are, in general, likely to be similar in biochemistry, whether they evolved or were designed." (Brand, 156.)
Both are wrong. There is no known biological reason, besides common descent, to suppose that similar morphologies must have similar biochemistry. At first, the statements made by Gish and Brand may seem obviously correct to the layperson, but all of molecular biology refutes this "common sense" correlation. In general, similar DNA and biochemistry give similar morphology and function, but the converse is not true - similar morphology and function is not necessarily the result of similar DNA or biochemistry. The reason is easily understood once explained; many very different DNA sequences or biochemical structures can result in the same functions and the same morphologies. As a very close analogy, consider computer programs. Netscape works essentially the same on a Macintosh, an IBM, or a Unix machine, but the binary code for each program is quite different. Computer programs that perform the same functions can be written in most any computer language - Basic, Fortran, C, C++, Java, Pascal, etc. and identical programs can be compiled into binary code many different ways. Furthermore, even using the same computer language, there are many different ways to write any specific computer program. In the end, there is no reason to suspect that similar computer programs are written with similar code, based solely on the function of the program. This is the reason why software companies keep their source code secret, but don't care that competitors can use the program - it is essentially impossible to deduce the program code from the function and operation of the software. The same conclusion applies to biological organisms, for very similar reasons.
Leonard Brand is evidently ignorant of this basic conclusion from modern genetics and molecular biology, since Camp quotes him stating:
"An alternate, interventionist hypothesis is that the cytochrome c molecules in various groups of organisms are different (and always have been different) for functional reasons. ...If we do not base our conclusions on the a priori assumption of megaevolution, all the data really tell us is that the organisms fall into nested groups without any indication of intermediates or overlapping of groups, and without indicating ancestor/descendant relationships. The evidence can be explained by a separate creation for each group of organisms represented in the cytochrome c data." (Brand, 158-159.)
Brand's entire argument is predicated upon his first sentence - "An alternate, interventionist hypothesis is that the cytochrome c molecules in various groups of organisms are different ... for functional reasons." Brand's hypothesis is uncharacteristically testable, which is fortunate. If we can demonstrate that cytochrome c molecules from different organisms are not different for functional reasons, then his argument is moot. In fact, it has been shown that the human cytochrome c protein works just fine in yeast (a unicellular organism) that lacks its own native cytochrome c gene, even though yeast cytochrome c differs from human cytochrome c over 40% of the protein. Even the cytochrome c genes from tuna, pigeon, horse, Drosophila fly, and rat all function well in yeast that lack their own native yeast cytochrome c. Furthermore, extensive genetic analysis of cytochrome c has demonstrated that the majority of the protein sequence is unnecessary for its function in vivo (a point covered in detail in the original version of the "29 Evidences" under Prediction 17). Obviously, Brand's "alternate hypothesis" is false, as is the rest of his argument. The cytochrome c gene is not exceptional in this regard - similar results have been found for all other ubiquitous genes tested. Biochemically, the reason for this observation is easily explained. Most of the sequence of a protein, like cytochrome c, is used for structural elements. As long as these structural parts of the protein fold into the same structure, the exact sequence is inconsequential. From X-ray crystallographic studies of the atomic structures of proteins, we know that many of the amino acids in any protein are not even used for structure and that many different amino acid sequences can fold into the same structure. Thus, since structure determines function, we fully expect that proteins with very different sequences will give the same function, and that is exactly what we observe. Accordingly, as explained earlier and contrary to Camp's argument, there is no reason to assume (aside from common descent) that similar morphologies and functions are due to similar molecular elements.
Camp finds yet another "problem" with the cytochrome c data and its implications for common descent:
The cytochrome c data on which Dr. Theobald relies present some puzzles from a neo-Darwinian perspective. First, the cytochromes of all the higher organisms (yeasts, plants, insects, fish, amphibians, reptiles, birds, and mammals) exhibit an almost equal degree of sequence divergence from the cytochrome of the bacteria Rhodospirillum. In other words, the degree of divergence does not increase as one moves up the scale of evolution but remains essentially uniform. The cytochrome c of other organisms, such as yeast and the silkworm moth, likewise exhibits an essentially uniform degree of divergence from organisms as dissimilar as wheat, lamprey, tuna, bullfrog, snapping turtle, penguin, kangaroo, horse, and human.
Though mechanisms of adaptive evolutionary change are not addressed in the "29 Evidences," Camp inserts a red herring here and shifts the subject by questioning the efficacy of "neo-Darwinism" to explain the degree of divergence observed in the cytochrome c sequences of various organisms. Camp's line of argumentation regarding rates is off the point. Common descent states nothing specifically about evolutionary rates, whether they must be fast, slow, variable, or constant, and the most commonly used phylogenetic methods make no rate assumptions. Explaining rates is the specific realm of genetic mechanisms, such as genetic drift, neutral theory, natural selection, gene flow, sexual selection, mutation, etc.
Nevertheless, Camp's discussion of cytochrome c rates is flawed and is not based in a working knowledge of the fundamentals of modern genetics or molecular biology. One of the main consequences of the functional redundancy of protein sequences (discussed in preceding paragraphs) is "neutral" evolution. The neutral theory describes the genetic behavior of mutations in protein and DNA sequences that have no, or very slight, selective effects. As mentioned above, about 70% of the cytochrome c protein is redundant. Changes in this 70% have virtually no effect upon function, and thus no selective effect - this 70% is selectively "neutral." One of the major predictions of the neutral theory is that the overall rate of evolution in neutral regions (where "evolution" means change in sequence) will be equal to the background rate of mutation. Mutations are largely due to factors that are relatively constant between different organisms, such as chemical and physical events (such as the spontaneous breaking or formation of bonds in DNA) and "errors" in the ubiquitous DNA repair machinery. Thus, neutral theory predicts that neutral rates of evolution should be nearly constant between organisms for functionally equivalent genes. It directly follows that the divergence of cytochrome c sequences should be nearly equal between two organisms and their last common ancestor. For example, according to the theory of common descent, bacteria, horses, and insects all share a common ancestor in the remote past. If rates of neutral evolution have been constant since that common ancestor, then the cytochrome c proteins of bacteria, horses, insects all should have evolved by the same amount since their last common ancestor. Accordingly, the divergence of cytochrome c between bacteria and horses should be nearly the same as the divergence between bacteria and insects. This is the answer to Camp's next question:
Why would the sequence divergence of cytochrome c between bacteria and horses be the same as the divergence between bacteria and insects? The presumed evolutionary lineage from the ancestral cell to a modern bacterium differs radically from the presumed evolutionary lineage from the ancestral cell to a modern horse, both of which differ radically from the presumed evolutionary lineage from the ancestral cell to a modern insect. How could a uniform rate of divergence have been maintained through such radically different pathways? According to Michael Denton, a molecular biology researcher, "At present, there is no consensus as to how this curious phenomenon can be explained." (Denton 1998, 291.)
And, as we have shown earlier, Michael Denton knows very little basic evolutionary theory1. The most likely reason why the rate of divergence has been quite uniform in all these "radically different" lineages is that cytochrome c does the exact same thing in all these lineages (it transports electrons in the fundamental cellular process of oxidative phosphorylation), and the mutations that do not destroy or change the function of cytochrome c are necessarily neutral. A better question is "why would the rate be nonuniform in these different lineages?" Contrary to Camp's suggestion, there is a strong consensus explanation for the cytochrome c sequences provided by neutral theory, the one just explicated above. Wesley Elsberry gives a more detailed explanation of the cytochrome c data in "Sequences and Common Descent." It is worthy to note here that the consensus explanation for cytochrome c sequence divergence does not involve natural selection, but only uses neutral theory, mutation, and purifying selection. To my knowledge, none of these standard genetic theories has been seriously criticized by anti-evolutionists (especially the "scientific" creationists).
An inquisitive person might ask further: "Should the divergence between the cytochrome c sequences from different organisms be exactly equivalent?" And the answer is no - mutation, recombination, and sexual reproduction are all stochastic processes (i.e., they have a large probabilistic element to them). We expect, even with exactly equivalent background rates of mutation, that amounts of divergence will be similar, but not equivalent. As with any stochastic process, there is a finite probability that "surprising" things might happen. For instance, whenever we flip 50 quarters, we expect that on average 25 will be heads and 25 will be tails. However, the probability that we will flip exactly 25 heads and 25 tails is rather small (~11%). There is a 0.1% chance that we will flip more than twice as many heads than tails. This means that if we repeat our 50-flip experiment 1000 times, we expect to flip more than twice as many heads as tails at least once (perhaps more). As Penny et al. put it in their article "Testing the Theory of Descent":
"From the proposed stochastic nature of the mechanism of mutation and selection it would be surprising if the trees were identical. Indeed, it would be more devastating to Darwinism if different sets of short sequences always gave identical trees." (Penny et al. 1991)
Thus, given the stochastic nature of genetics, we in fact expect that independently derived trees occasionally will not match exactly and that rates of divergence will vary for the same reasons.
Camp evidently does not understand the probabilistic nature of genetics, since he is surprised at a small minority of "anomalous" cytochrome c sequences:
Moreover, the notion that the rates of divergence remain uniform regardless of evolutionary pathway does not fit all of the cytochrome c data. For example, referring to Dr. Theobald's Figure 1 (reproduced above), lampreys, carp, and bullfrogs allegedly shared a common ancestor above the node labeled "vertebra." Since that time, the branch leading to carp and bullfrogs evolved independently of the branch leading to lampreys. If the rates of cytochrome c divergence remain uniform regardless of evolutionary pathway, then the degree of sequence variance between the cytochrome c of lampreys and carp would be essentially the same as the degree of variance between the cytochrome c of lampreys and bullfrogs. That is not the case. The variance between the cytochrome c of lampreys and carp is 12%, whereas the variance between lampreys and bullfrogs is 20%. (See matrix in Davis and Kenyon, 37.)
These results are expected if genetics is fundamentally probabilistic instead of deterministic, as it is. Camp states: "If the rates of cytochrome c divergence remain uniform regardless of evolutionary pathway, then the degree of sequence variance between the cytochrome c of lampreys and carp would be essentially the same as the degree of variance between the cytochrome c of lampreys and bullfrogs." This is incorrect, and displays a lack of understanding of probability and statistics. Uniform rates are expected to give unequal results (see the discussion on mathematics below after the green box). Even so, Camp is incorrect in his details. I cannot speak for the original citation (Davis and Kenyon 1993), but the values that Camp gives for the divergences of lamprey, carp, and bullfrog cytochrome c are incorrect. The true divergence between the cytochrome c of lampreys and carp is 19%, and the divergence between lampreys and bullfrogs is 20%. Camp has since explained that he was using an outdated source (over thirty years old) for these figures, yet he still "stand[s] by" these figures - even though the sequences I have given above were updated in 1981, 1984, and 2000 (this is easily verified simply by clicking the links I have given).
Camp continues with his surprise that some of the cytochrome c sequences appear anomalous:
Second, the sequences of cytochrome c sometimes differ inversely to the presumed evolutionary proximity of the organisms being compared .... The cytochrome c of the rattlesnake varies in 22 places from that of the turtle but only in 14 places from that of a human. ... the cytochrome c of the human varies in 12 places from that of a horse but only in 10 places from that of a kangaroo. ... Such discrepancies between traditional phylogenies and those based on cytochrome c are well known.
As stated before, such results are expected if heredity is a stochastic process, as it is. Because genetics is stochastic, the theory of common descent does not predict that phylogenetic trees made with single genes will perfectly match other phylogenetic trees - they must be similar, but not necessarily identical. As already explained in the "29 Evidences":
"Gene trees are not equivalent to species trees: from simple Mendelian genetics we know that genes segregate individually, and that throughout time individual genes do not necessarily follow organismic genealogy. An obvious example is the fact that while you may have brown eyes, your child may have the genes for blue eyes - but that does not mean your child is not your descendent, or that your brown-eyed children are more closely related to you than your blue-eyed children. Including multiple genes in the analysis is a solution to this conundrum." (Avise and Wollenberg 1991)
Apparently, Camp not only misunderstands basic genetics but also does not understand basic mathematics (probability and statistics), as he later chides:
In other words, evolution expects uniform divergencies [sic] of protein sequences, but it also expects nonuniform divergencies if and when they arise. It is an amorphous theory indeed.
Figure C1. Distribution of genetic distances between human and mouse genes. The histogram is the actual data from 2,019 human and mouse genes. The solid curve shows the expected distribution of genetic distances assuming only a constant rate of background mutation (~10-9 substitutions per site per year) (reproduced from Figure 3a in Kumar and Subramanian 2002).
There is nothing inconsistent with a uniform rate and nonuniform results. That is basic statistics. As a very simple example, in the above discussion of quarter flipping, the rate of "heads" is exactly 0.5 heads per flip. This rate is exactly constant. However, there is nothing unusual (or "amorphous") about flipping five heads in a row, or five tails in a row (corresponding to an average observed rate of one head per flip and zero heads per flip, respectively). Such results are expected if coin flipping is a stochastic process, as it is. We expect these results about 6% of the time. In fact, the outcome of a stochastic process like coin flipping, radioactive decay, or spontaneous mutation should approximate a Gaussian bell-shaped curve (also known as a "normal curve"), as explained in any entry-level probability and statistics text.
Similarly, if rates of molecular evolution are exactly constant, we clearly expect that the genetic divergences between species will be unequal in most cases. In fact, we expect that neutral genetic divergences will be distributed about a Gaussian bell-shaped curve centered on the average rate of molecular evolution. Many species should have more divergence than average (like the rattlesnake cytochrome c), and many species should have less divergence than average (like the kangaroo cytochrome c). Likewise, we expect that, if background mutation rates are exactly constant, genetic divergences between neutral regions of different genes between two species will also be distributed about a bell-shaped curve. In fact, this is precisely what is observed (e.g. see the data for humans and mice in Figure C1 at left; Kumar and Subramanian 2002). For instance, from basic probability theory, we expect that 15% of genes between humans and mice should evolve over 36% faster than the average constant rate, over 2% should evolve about 70% faster than the average constant rate, and that about 0.4% should evolve over 210% faster than the average rate. And, as the figure shows, this is exactly what we observe in humans and mice. Note, this means that in a comparison of one hundred randomly sampled human and mouse genes, we expect that the most divergent gene will have 0% similarity in neutral regions, while the least divergent gene will have nearly 100% similarity in neutral regions (see the lower left tail of the bell curve in Figure C1). These results are predicted, based upon simple math, if the average background mutation rate is completely constant in both the human and mouse lineages. This fact illustrates nicely why it is premature to base strong evolutionary conclusions on an analysis of only one gene (like the cytochrome c gene) or even a few genes; strong conclusions can only be based upon a large sampling of genes.
It is rather presumptuous to label a theory "amorphous", when said theory simply follows basic laws of mathematics.
As stated earlier, Camp's discussion of rates is a red herring anyway. Common descent makes no specific predictions concerning rates. Even including all the known discrepancies, the cytochrome c phylogeny and the traditional morphological phylogeny match to an extremely high degree with extremely high statistical significance (Penny et al. 1982). And, as expected, including more genes in the analysis increases the correspondence between phylogenetic trees (Penny et al. 1982; Baldauf et al. 2000; Hedges 1994; Hedges and Poling 1999). In the end, the molecular phylogenetic data, such as the cytochrome c data, provide one of the strongest and most irrevocable confirmations of common descent.
Universal common ancestry affirms only that all creatures descended from the same ancestor. There is nothing about that affirmation that requires conformity to the standard phylogenetic tree.
Again, Camp is mistaken. If all organisms are united by descent from a common ancestor, then there is one single true historical phylogeny for all organisms, just like there is one single true historical genealogy for any individual human. It follows that if there is one true phylogeny, then all organisms fit in that phylogeny uniquely. In other words, all organisms, both past (e.g. fossils) and present, must conform to the true phylogeny. Since the standard phylogenetic tree is the best approximation of the true historical phylogeny, we expect that all fossilized animals should conform to the standard phylogenetic tree within the error of our scientific methods. If fossilized animals do not, then there are only two logical possibilities - either our estimation of the true phylogeny is incorrect, or there is no true phylogeny (i.e. common descent is false). This last point leads in to Camp's next mistake:
A phylogenetic tree is merely a diagram that reflects current evolutionary thinking about the relationships of the taxa included. Branches are arranged on the tree on the assumption of evolution and according to perceived similarities in selected traits. The relationships of some branches are viewed more dogmatically than the relationships of others, but none of the branches are set in stone.
No branches are viewed "dogmatically" - some branches have strong support from the data and are very unlikely to be incorrect if common descent is true, while other branches are known with less confidence. Thus, fossilized organisms that contradict the very well-supported branches would be inconsistent with common descent.
Since phylogenies are by nature provisional, the suggestion that the hypothesis of common descent would be falsified by "[a]ny finding of mammal/bird intermediates" is mistaken. Should a strikingly birdlike mammal be discovered, the standard tree simply would be modified to accommodate the new creature, after wrangling over its placement in the schema.
This demonstrates an underlying confusion about the scientific method. Everything in science is by nature provisional. However, some things are more "set in stone" than others, and that is where the concept of falsifiability comes in. Even Camp's anti-evolutionist source Walter ReMine understands that science is at once provisional and falsifiable:
"The criterion of falsifiability indicates science is tentative. Science never achieves certainty. Science is not rigid and dogmatic ... Because our observations are limited, we can only attain fine shades of near certainty. ... While science is tentative, it is not flimsy. Science can carry enough weight that we often speak of a given theory as a fact. ... Science is also tentative about falsifying a theory. It can be difficult to falsify a theory with all the finality we would like. ... By testing ... we attain greater confidence in identifying false hypotheses." (ReMine 1993, p. 34, emphasis in the original)
Though ReMine often misses the mark, these statements capture the essence of testability in science quite well. The standard phylogenetic tree, as currently supported by massive amounts of data, is highly inconsistent with true mammal-bird intermediates. The phylogenetic tree could not be modified to accommodate such creatures - they would not fit anywhere.
Ironically, the inflexibility of this aspect of the standard phylogenetic tree is well-evidenced by Camp's next statements:
The ease with which this precise adjustment could occur was illustrated two decades ago, when "[t]he reality of the 'mammal-bird,' a hypothetical common ancestor of birds and mammals, [was] a contentious issue in modern systematics." (Mike Benton, 18.) Brian Gardiner's cladistic analysis indicated that birds were most closely related to mammals, which relationship was supported by two Cambridge scientists' analysis of molecular data. .... Branches can be rearranged, even between mammals and birds, without skipping a beat in terms of commitment to common ancestry.
Camp is, again, self-contradictory. How can "mammal-birds" at once be contentious and also be accommodated with "ease", "without skipping a beat"? They can't! The Benton article to which Camp refers (Benton 1984) is wholly devoted to exploring the extremely surprising (and, at the time, quite troubling) idea that the standard phylogenetic tree could be so very, very wrong about birds and mammals. There was nothing "easy" about this possibility - it threatened to shake the very roots of the well-established phylogeny of life. For example, in response to Gardiner's outlandish analysis, zoologist Barry Cox wrote this in a News and Views article in Nature:
"[Gardiner is] now assaulting even the most fundamental roots of the systems of relationship that the traditional evolutionary morphologists have developed. ... Gardiner has now used cladistic techniques to transform the whole system of tetrapod classification. ... The results are so different ... that a headlong collision is inevitable, for there can be no minor shifting of viewpoints or emphasis that could lead to a reconciliation or synthesis. ... Gardiner's suggestions [are] completely at odds with the palaeontological record ..." (Cox 1982)
Does this sound like biologists accepted this "precise adjustment" with "ease"? Does this sound like these "Branches can be rearranged, even between mammals and birds, without skipping a beat"? In a vain effort to make his point, Camp felt it necessary to grossly misrepresent the true status of the controversy. In his in depth criticism of Gardiner's analysis, Oxford zoologist T. S. Kemp wrote:
"... many, probably the great majority of vertebrate biologists have dismissed Gardiner's hypothesis as simply outrageous ..." (Kemp 1988, p. 69)
Notwithstanding Camp's unfounded statements, Gardiner's analysis was not incorporated or reconciled, nor were branches rearranged in the consensus phylogeny. In reality, the "contentious issue" was short-lived, as it was soon shown by several independent researchers that Gardiner's cladistic analysis was fundamentally flawed at many levels (Benton 1985; Benton 1991; Gauthier et al. 1988; Hopson 1991; Kemp 1988; Witmer 1991). Likewise, the supposed corroborating molecular evidence was analyzed incorrectly. At the time (the early '80's), cladistics and molecular phylogenetics were just coming into their own, and the proper techniques were still getting worked out. In fact, improvements are still being made today, as is true of technological innovations in all scientific fields. In the end, all these analyses contributed positively to our knowledge via improved phylogenetic techniques - but they did not radically alter the consensus phylogeny. Quite the opposite, the improved analyses have confirmed that earlier biologists were correct.
Of course, the discovery of a strikingly birdlike mammal would not necessarily force a shift in thinking about the relationship of mammals and birds (a placing of their branches next to each other). The birdlike features could be attributed to convergent evolution. Many organisms are believed by evolutionists to have evolved similar traits independently. ... If the mammal's birdlike traits were judged to be the result of convergent evolution, the species would be shown on the phylogenetic tree as a subset or side branch of mammals that was unrelated to birds.
Camp's point is true, but only for limited, trivial cases. Convergence is more likely the less complex the trait. However, for very complex traits, true structural convergence is essentially impossible in the context of common descent and gradualism. For instance, independent evolution of bird flight feathers is widely considered to be out of the realm of possibility. Camp gives an example of possible convergence in an attempt to support his above statements:
(In fact, some experts believe that the birdlike features of dromaeosaurids, the dinosaurs considered by most experts to be the sister group to birds, arose independently rather than by inheritance from the ancestor of birds.)
Though thought unlikely by most paleontologists, such convergence is possible, since the "bird-like" features of dromaeosaurids are in most cases very subtle. The "experts" to which Camp refers here are Alan Feduccia and a few other like-minded biologists. They maintain a minority opinion that dromaeosaurids and birds are both independent descendents of thecodonts (thecodonts are primitive dinosaur-like reptiles). In any case, dromaeosaurids are much more similar to thecodonts than they are to modern birds. Thus, Feduccia's suggestion of convergence is not so radical, even though the most parsimonious hypothesis is that birds are the descendents of dromaeosaurids, which in turn are the descendents of thecodonts. In contrast, the claim that a mammal independently evolved bird flight feathers is extremely radical from an evolutionary perspective. Camp's example of possible convergence does nothing to support his erroneous opinion that evolutionary biology could easily accept strikingly bird-like mammals.
The shift in thinking over the last 30 years about the relationship of dinosaurs and birds is an example of a generally accepted phylogenetic adjustment, albeit at a lower taxonomic level. From the publication of Gerhard Heilmann's The Origin of Birds in 1926, it was a matter of textbook orthodoxy that birds were more closely related to thecodonts (an order of reptiles) than to theropods (a suborder of a different order of reptiles). Thus, the discovery in 1964 of the birdlike theropod Deinonychus was contrary to phylogenetic expectations. Today, however, the standard phylogeny shows birds more closely related to theropods than to thecodonts.
As with the Gardiner cladistic analysis, Camp feels the need to misrepresent the true situation in order to make a point. Camp's claim that "the discovery in 1964 of the birdlike theropod Deinonychus was contrary to phylogenetic expectations" is false and does not represent the true status of the scientific situation. Coelurosaurs are theropods, and Deinonychus (the "surprise" mentioned by Camp above) is a coelurosaur. Here are Gerhard Heilmann's statements about bird origins from The Origin of Birds:
"On turning from the clumsy Predentates to the Coelurosaurs, we meet with quite a different type; ... Hollow bones of very light structure, exceedingly long hind-limbs with strong elongate metatarsals and a "hind-toe," a long, narrow hand, a long tail and a long neck, large orbits and ventral ribs - these are bird-features immediately conspicuous." (Heilmann 1926, p. 165-166)
"... the striking points of similarity between Coelurosaurs and birds pertained to nearly all the parts of the skeleton ... From this it would seem rather obvious that it is amongst the Coelurosaurs that we are to look for the bird ancestor. And yet, this would be too rash, for the very fact that clavicles are wanting would in itself be sufficient to prove that these saurians could not possibly be the ancestors of birds. ... We have therefore reasons to hope that in a group of reptiles closely akin to the Coelurosaurs we shall be able to find an animal wholly without the shortcomings here indicated for a bird ancestor [i.e. the lack of clavicles]." (Heilmann 1926, p. 183-184)
Thus, the discovery of a bird-like theropod, the coelurosaur Deinonychus, was clearly anticipated by Heilmann, since Heilmann already considered coelurosaurs and other theropods to be quite bird-like. Deinonychus is a coelurosaur; many coelurosaurs had been known before 1964 (such as Ornithomimus antiquus, found in 1865, O. velox, 1890, O. edmontonicus, 1933, O. lonzeensis, 1903, O. sedens, 1892, Paronychodon lacustris, 1876, Ornitholestes hermanni, 1903, Proceratosaurus bradleyi, 1910, Compsognathus longipes, 1859, Struthiomimus altus, 1902, Thecocoelurus daviesi, 1888, Chirostenotes pergracilis, 1924, Oviraptor philoceratops, 1924, Therizinosaurus cheloniformis, 1954, Alectrosaurus olseni, 1933, Albertosaurus sarcophagus, 1905, A. grandis, 1890, Tarbosaurus efremovi, 1955 T. bataar, 1955, Tyrannosaurus rex, 1905, Velociraptor mongoliensis, 1924, Dromaeosaurus albertensis, 1922, D. cristatus, 1876, D. explanatus, 1876, and D. gracilis, 1888). Coelurosaurs were well-known to be strikingly bird-like in many respects, as the Heilmann quotes above demonstrate unequivocally. Thomas. H. Huxley had noted many of the close similarities between theropods (including coelurosaurs) in the mid-19th century (Huxley 1868; Huxley 1870a), as had many other prominent paleontologists in the early 20th century (Witmer 1991, p. 437-447). Heilmann had reservations about theropods as bird ancestors only because, at the time, theropods were not known to have clavicles (a weak argument, of course, since it is based upon negative evidence - it is now known that clavicles fossilize poorly). Subsequent findings have established that many theropods indeed have clavicles, such as Segisaurus, Velociraptor, Euparkeria, Ingenia, Ornithosuchus, Oviraptor, Saltoposuchus, and Ticinosuchus (Barsbold et al. 1990; Bryant and Russel 1993). Some of these dinosaurs even have true furculae (wishbones), a character once thought to be only found in birds. Furthermore, it was Thomas H. Huxley who originated the hypothesis of the theropod ancestry of birds all the way back in 1868 (Huxley 1868, p. 74).
The resurrection of the theropod ancestry hypothesis was initiated by J. H. Ostrom in 1973, based upon his re-evaluation of the similarities between Archaeopteryx and coelurosaurs (Ostrom 1973). Ostrom listed 21 specific shared derived characters between Archaeopteryx and coelurosaurs as a taxonomic group (not just Deinonychus) which had mostly been overlooked throughout the years. The discovery of the bird-like coelurosaur Deinonychus in 1964 (first described in Ostrom 1969) was further support for the theropod ancestry hypothesis, but it was not a surprise that "was contrary to phylogenetic expectations" - it was directly in-line with contemporary phylogenetic expectations. In reality, in 1964 the hypothesis that birds were descendents of thecodonts was thought most likely, yet whether theropods were the intermediates between thecodonts and birds was still an open question lacking any firm supporting evidence either for or against (Bock 1969; Feduccia 1996, p. 55-56; Witmer 1991, p. 437-447). Today, with the increased knowledge given by the acquisition of many more fossils, and with the use of rigorously developed cladistic techniques, birds are still thought to be the descendents of certain thecodonts (or more correctly, of archosauromorphs, which are a well-defined class of thecodonts - "thecodont" is an outdated, grab-bag term which is no longer used in the modern paleontological literature). Ostrom specifically postulated a "thecodont-coelurosaur-Archaeopteryx-Aves phylogeny" (Ostrom 1973). Birds are descended from "thecodonts" via theropods.
Furthermore, Camp claims that, based on Heilmann's analysis, "it was a matter of textbook orthodoxy that birds were more closely related to thecodonts ... than to theropods" - a statement which, strictly, is incorrect. Heilmann only thought that coelurosaurs were not bird ancestors, and he thought it likely that thecodonts, as a group, were bird ancestors. That does not mean that birds are necessarily more closely related to thecodonts than to theropods (or coelurosaurs). For instance, are you more closely related to your siblings or to your great great great great grandfather? Of course, you are much more closely related to your siblings - yet they are not your ancestors (siblings share half their DNA on average, whereas an individual and her great great great great grandfather share only 1/64th of their genes). Likewise, birds could be more closely related to coelurosaurs than thecodonts, while simultaneously being the descendants of thecodonts but not of coelurosaurs. In fact, this is likely what Heilmann thought, as he says:
"We have therefore reasons to hope that in a group of reptiles closely akin to the Coelurosaurs we shall be able to find an animal wholly without the shortcomings here indicated for a bird ancestor. Such a group is possibly the Pseudosuchians [Pseudosuchians are 'thecodonts'] ..." (Heilmann 1926, p. 183-184)
Back to Camp's criticism of the prediction of intermediate/transitional organisms:
The assertion that all fossilized animals conform to the standard phylogenetic tree is unprovable, because one can never be sure that all fossilized animals have been discovered.
Camp is clearly correct, but this is certainly not a problem. Camp has pinpointed the very reason why this prediction is falsifiable and thus scientific. The assertion that all fossilized animals conform to the standard phylogenetic tree is unprovable, yes, like all scientific statements - but it is relatively simple to prove this assertion false. Which, by the way, is the essence of falsifiability.
Interestingly, this turns out to be yet another instance where Camp contradicts himself. At the end of his criticism of prediction 15, Camp writes this non sequitur:
The suggestion that universal common ancestry would be falsified by "the discovery of a mammal without crossed gastrointestinal and respiratory tracts, or a reptile or mammal without blindspots in its eyes" is incorrect. It is another example of taking what is known not to exist and claiming that evolution predicts it could not exist.
In one instance Camp (correctly) asserts that "one can never be sure that all [organisms] have been discovered," and that, therefore, we can never prove a given prediction of common descent about organisms. Later, when it is more convenient to take the opposite stance, Camp (incorrectly) asserts that a prediction of common descent is not really a prediction, since certain features of organisms are already "known not to exist." How can we know that all mammals and reptiles have crossed gastrointestinal tracts and blindspots if we cannot be sure that we have discovered all mammals and reptiles? We can't. We can never be certain of what exists with incomplete knowledge of the world, and this is precisely why scientific predictions, like the predictions of common descent, are testable, confirmable, and falsifiable.
But more importantly, the premise [that all fossilized animals conform to the standard phylogenetic tree] turns out to be merely a restatement of the claim of nested hierarchy. It adds nothing to the case for common ancestry.
To the contrary, it is not simply a restatement of the nested hierarchy. The "nested hierarchy" statement, given in prediction 2, is that modern organisms should conform to a nested hierarchy if common descent is true. It is tested with modern species by zoologists, botanists, etc. Prediction 3 concerns the morphologies of organisms that existed in the past. It is tested with fossils by paleontologists. In principle, prediction 2 could pass, while prediction 3 could fail, or vice versa. Therefore, they are not the same. Both predictions add to the case for common ancestry, since they are independently tested and confirmed.
... according to the definition of "intermediate" given in the article, dromaeosaurids are not reptile-bird intermediates and synapsids are not reptile-mammal intermediates. An "intermediate form" is defined as "[a] fossil or modern species that displays characters definitive of two or more different taxa" (emphasis supplied). Dromaeosaurids do not display characters that are definitive of both reptiles and birds (which is why they are not considered birds), and synapsids do not display characters that are definitive of both reptiles and mammals (which is why they are not considered mammals).
Camp is splitting hairs over terminology here. The word "definitive" is not a technical phylogenetic term, and it is intended to mean "unequivocal," not necessarily "unique" (in cladistic terminology such a "definitive character" would be equivalent to a synapomorphy, but not always an autapomorphy). Dromaeosaurs share many definitive characters with birds, such as a furcula, a retroverted pubis, very long forelimbs, pneumatic (hollow) bones, and a relatively large brain. Dromaeosaurs also share many definitive characters with reptiles, such as teeth, free articulating trunk vertebrae, a long tail with free vertebrae (no pygostyle), less than six sacral vertebrae, unfused metacarpals, unfused metatarsals, and gastralia. As listed above, dromaeosaurs share many characters with birds, but they also lack many unique characters that birds have (such as wings) - so they are not birds. Dromaeosaurs are indeed intermediates between birds and reptiles (especially dinosaurs) according to the given definition, and similarly, synapsids are indeed intermediates between mammals and reptiles.
In footnote 13, Camp reiterates this error, plus making a few new ones:
Dromaeosaurids are considered a sister group to birds, meaning they are believed to have shared with birds a most recent common ancestor. They are not believed to have been in the actual lineage of birds. In fact, they possess certain specializations, such as the stiffened tail, that make them ill suited as ancestors. Of course, the presumed common ancestor of birds and dromaeosaurids is thought to have been quite dromaeosaurid-like. As already noted, dromaeosaurids do not qualify as reptile-bird intermediates according to Dr. Theobald's definition.
Camp's concern about "actual lineage" is another misleading red herring and is addressed in the next section. The statement that the stiffened tail makes dromaeosaurids "ill suited" as bird ancestors is ridiculous; birds have extremely stiffened tails (i.e. the pygostyle). Dromaeosaurs indeed have specialized structures that are not likely to be found in bird ancestors, but the stiffened tail itself is not one. The pertinent derived structures are found in the tails of Dromaeosaurs. The stiffened tails of Dromaeosaurs have specialized rod-like extensions of the vertebral zygapophyses which are not found in the stiffened tails of birds.
The assertions that there are "no morphological gaps" in the alleged dinosaur-to-bird transition and that there is an "exquisitely complete series of fossils" for the alleged reptile-to-mammal transition are debatable, to say the least. I have elsewhere tried to point out some of the limitations of those claims (see, "On the Alleged Dinosaurian Ancestry of Birds" and "Reappraising the Crown Jewel").
A detailed criticism of the two articles cited above will not be given here. However, I will note that both criticisms boil down to two main points: (1) that some transitional fossils are more derived than would be required for ancestors, and (2) that some transitional fossils are not in perfect chronological order relative to their cladistic rank. Neither point carries any weight as evidence against common descent, for the simple reason that common descent does not predict either (1) that transitional fossils are ancestors, or (2) that transitional fossils should be in perfect chronological order relative to their cladistic rank. If common descent does not make these claims, then observations that contradict these claims cannot be evidence against common descent. Either Mr. Camp does not fully understand modern evolutionary theory or he misrepresents its implications.
Point (2), concerning the chronological order of transitional forms, is dealt with in the next section covering Prediction 5. For point (1), as was stated concerning intermediate/transitional forms in the original prediction 4 and prediction 25:
"A subtle, yet important point is that a strict cladistic evolutionary interpretation precludes the possibility of identifying true ancestors; only intermediates or transitionals can be positively identified. (For the purposes of this article, transitionals and intermediates are considered synonymous.) The only incontrovertible evidence for an ancestor/descendant relationship is the observation of a birth; obviously this is normally rather improbable in the fossil record. Intermediates are not necessarily the same as the exact predicted ancestors; in fact, it is rather unlikely that they would be the same. Simply due to probability considerations, the intermediates that we find will most likely not be the true ancestor of any modern species, but will be closely related to the predicted common ancestor. The minor implication concerning fossil intermediates is that the intermediates we do find will likely have additional derived characters besides the primitive characters that identified them as intermediates. Because of these considerations, when a new and important intermediate fossil species is discovered, paleontologists will usually note that the transitional species under study is probably not an ancestor, but rather is an evolutionary 'side-branch.'"
"... given what we know of modern species dynamics and recent extinction rates, we know that the majority of organisms will eventually go extinct (Diamond 1984; Diamond 1984; Wilson 1992, ch. 12; Futuyma 1998, pp. 722-723). By extrapolation, the majority of past organisms also have gone extinct. Thus, we should reasonably expect that the predicted common ancestors had many other descendants and relatives that did not leave descendants which survive today. In short, we predict that the majority of fossil species that we find should not be the actual common ancestors of modern species, but rather they should be related organisms that eventually ended in extinction."
To restate - common descent predicts that we may find transitional forms, but transitional forms are not necessarily the same as common ancestors. Presumably, Mr. Camp does understand this aspect of modern evolutionary theory but has chosen to misrepresent it, as he has written this elsewhere:
As for the concept of "transitional forms" in general, the term originally meant a creature that was part of the evolutionary transition from species A to species D, so it was necessarily tied to lineage. When evolutionists came up empty on that score, they changed the definition. (This shift was still in process in 1984 when Cracraft wrote, "Part of the confusion apparent *in the scientific literature* . . . I suggest, stems from the definition of 'transitional form.'") They now claim as a "transitional form" any creature that is stratigraphically and morphologically between any two taxa, without any regard for whether the particular species represent a lineage. (And they sometimes take creatures that are NOT stratigraphically intermediate and simply assume they must have been.) This is a useful PR strategy for evolutionists because whenever John Q. Public hears "transitional form," he still thinks "lineage."
In other words, Camp understands that common descent, at least in its modern incarnation, does not predict that transitional forms are necessarily common ancestors. (Camp is incorrect here in his assessment that stratigraphy bears upon whether an organism is considered a transitional form or not. A transitional form is defined purely in terms of morphology, regardless of age.) However, Camp nevertheless persists in arguing that fossils which are transitional, yet have other derived characters that exclude them as ancestors, are problematic for common descent. He persists in making this misleading argument in the two articles cited above and in his critique of the "29 Evidences," as well as in The Overselling of Whale Evolution (all updated as recently as October 7, 2001). Furthermore, Camp mistakenly claims that transitional form originally meant something other than it does now, and that evolutionary biologists were compelled to adjust the definition due to conflicting evidence (a position apparently borrowed from Walter ReMine, e.g. ReMine 1993, p. 294-296, 414-415). Both Camp and ReMine are incorrect; evolutionary biologists have not "changed the definition," nor have they changed the relevant prediction. First, the definition is easily and naturally derived from a phylogenetic tree and, second, Charles Darwin used the modern definition in The Origin of Species in 1859 when he first proposed the modern theory of common descent and first introduced phylogenetic trees to the scientific world. The following quotes illustrate this point quite clearly:
... we ought to find in nature, not the actual transitional gradations by which each complex instinct has been acquired -- for these could be found only in the lineal ancestors of each species -- but we ought to find in the collateral lines of descent some evidence of such gradations; or we ought at least to be able to show that gradations of some kind are possible; and this we certainly can do. (Darwin 1872, p. 320)
Referring to his famous figure, Darwin explained:
It is worth while to reflect for a moment on the character of the new species F14, which is supposed not to have diverged much in character, but to have retained the form of (F), either unaltered or altered only in a slight degree. In this case its affinities to the other fourteen new species will be of a curious and circuitous nature. Being descended from a form that stood between the parent-species (A) and (I), now supposed to be extinct and unknown, it will be in some degree intermediate in character between the two groups descended from these two species. But as these two groups have gone on diverging in character from the type of their parents, the new species (F14) will not be directly intermediate between them, but rather between types of the two groups; and every naturalist will be able to call such cases before his mind. (Darwin 1872, p. 157)
... the diagram throws light on the affinities of extinct beings, which, though generally belonging to the same orders, families, or genera, with those now living, yet are often, in some degree, intermediate in character between existing groups; and we can understand this fact, for the extinct species lived at various remote epochs when the branching lines of descent had diverged less. (Darwin 1872, p. 158)
Supposing B and C to be two species, and a third, A, to be found in an older and underlying bed ... A might be the actual progenitor of B and C, and yet would not necessarily be strictly intermediate between them in all respects. So that we might obtain the parent-species and its several modified descendants from the lower and upper beds of the same formation, and unless we obtained numerous transitional gradations, we should not recognize their blood relationship, and should consequently rank them as distinct species. (Darwin 1872, p. 426)
More relevant evidence is given from the early evolutionary biologist, Thomas Henry Huxley:
Every fossil which takes an intermediate place between forms of life already known, may be said, so far as it is intermediate, to be evidence in favour of evolution, inasmuch as it shows a possible road by which evolution may have taken place. ... Suppose A, B, C to be three forms, while B is intermediate in structure between A and C. Then the doctrine of evolution offers four possible alternatives. A may have become C by way of B; or C may have become A by way of B; or A and C may be independent modifications of B; or A, B, and C may be independent modifications of some unknown D. ... it is always probable that one may not hit upon the exact line of filiation, and, in dealing with fossils, may mistake uncles and nephews for fathers and sons.
I think it necessary to distinguish between [...] classes of intermediate forms, as intercalary types and linear types. When I apply the former term, I merely mean to say that as a matter of fact, the form B, so named, is intermediate between the others, in the sense in which the Anoplotherium is intermediate between the Pigs and the Ruminants - without either affirming, or denying, any direct genetic relation between the three forms involved. When I apply the latter term, on the other hand, I mean to express the opinion that the forms A, B, and C constitute a line of descent, and that B is thus part of the lineage of C. (Huxley 1870b, p. 348-350)
From a popular introductory evolutionary college textbook from the '50s and '60s:
[Intermediate form] always included the idea of a form standing midway between two groups of animals now clearly separate from each other. (Moody 1953, p. 188)
From a modern introductory evolutionary textbook:
transitional form A species that exhibits traits common to ancestral and derived groups, especially when the groups are sharply differentiated. (Freeman and Herron 2001, p. 686)
From all these quotes it is evident that early evolutionary biologists did not necessarily equate "intermediate" with "ancestor," and that intermediates do not need to be part of a direct genealogical lineage. This has been clear from the outset. Even in the cases where intermediates are ancestors, Darwin explained that ancestors may have derived characters which were subsequently lost in their descendents. Finally, neither Darwin nor Huxley expected that we should necessarily identify common ancestors, but rather that we should find intermediates. These remain the modern evolutionary views (they are now most often couched in cladistic terminology).
Camp complains that "This is a useful PR strategy for evolutionists because whenever John Q. Public hears 'transitional form,' he still thinks 'lineage.'" This gripe is humorous, since "transitional form" is a scientific term, and as such should be defined by scientists as they wish. It's as if Camp were complaining because in Newtonian physics the product of mass and acceleration is called a "force," and that "force" is inappropriate because it sounds too "mystical" to the layperson. Besides, if evolutionary biologists wanted to convey "lineage," the most obvious tact would be to use the term "ancestors" in place of "transitional forms" - but that would be misleading. In spite of Camp's bias, "transitional form" is a perfectly accurate description which has no genealogical connotations.
Consequently, since the terms "intermediate" and "transitional" have been defined since the genesis of evolutionary theory, Mr. Camp has no justification in perpetuating misleading arguments and statements concerning the proper evolutionary definitions of these terms and the relevant predictions of common descent. In doing so, Camp joins the ranks of other creationist anti-evolutionists who knowingly reinforce the widespread, yet incorrect, lay public perception that transitional forms are always common ancestors.
Mr. Camp concludes this section with a veiled attack upon the scientific method itself:
But even if one granted that reptiles evolved into a bird and a mammal, that would not establish that reptiles and all other organisms descended from a common ancestor, which is the proposition being argued. The difference between a bacterium and a reptile, not to mention the other organisms, is considerably greater than the difference between a reptile and a bird or a reptile and a mammal. So the fact a reptile could evolve into a bird or a mammal would not mean that a bacterium could evolve into a reptile and everything else. In fact, granting that reptiles evolved into a bird and a mammal would not even establish that all birds and all mammals descended from a reptile. That would be an assumption.
In this paragraph Camp is criticizing the fundamental scientific practice of extrapolation. Extrapolation underlies all of science; without extrapolation, we could not make any scientific conclusions or predictions. When we sent the Surveyor 1 spacecraft to the moon in 1966, we assumed that Newton's laws of physics operated on the moon, just as they operate on the earth. We assumed this even though we had never sent anything to the moon's surface before. And, of course, we were correct - so correct that two years later we entrusted the lives of several men to our assumption. Our assumption was the result of extrapolating from what was known (earth bound physics) to what was unknown (lunar physics). Furthermore, we assume that Newton's laws of physics hold on Neptune and Uranus, even though we have never explored the surfaces of those planets. Likewise, once we have established that certain reptiles have evolved into birds and mammals, we can easily assume that all birds and mammals are descendents of reptiles. We can assume this because it is trivial to conclude that all birds are related by common descent. If a reptile can evolve into a bird then certainly a bird can evolve into another bird. This particular extrapolation should not be controversial for Mr. Camp, since creationists of all stripes generally believe that all birds are modified descendents of an original created bird "kind." Once we have established that something like a bird can evolve from a reptile, we assume that similar things happened with other species and in other lineages.Camp has replied to this:
According to Dr. Theobald, I am here denying the legitimacy of the principle of extrapolation and thus depriving science of its ability to make any conclusions or predictions. All I am doing is pointing out the difference between what is extrapolated or assumed and what is proved.
Once again we find evidence of Camp's misunderstanding of basic science and the scientific method. Camp errs in claiming that there is a difference between what is extrapolated or assumed and what is proven. In science, nothing can be proven. The reason nothing can be proven is very simple - all scientific conclusions rely upon the fallacy of affirming the consequent, and in doing so they rely upon inductive extrapolation. In contrast, a theory conceivably could be shown to be false by using a valid modus tollens argument. These issues were the foundation behind Sir Karl Popper's reasoning and his falsifiability criterion for the scientific method. In the end, though, even falsification is flawed, as the premises of any modus tollens argument cannot be proven since their validity is also established by affirming the consequent. Mr. Camp surely is aware of this, as he appears to be well-versed in logic. To clarify the import of this scientific dilemma, consider the following example provided by Mr. Camp in his discussion of extrapolation:
Earth-bound physics can be extrapolated to the solar system and universe, but that would not mean the extrapolation was justified. That would have to be demonstrated by evidence (which it was prior to the moon landing in 1969).
Camp thinks that it was valid to assume that the laws of physics worked on the moon like they do on the earth, because he thinks this particular extrapolation was proven prior to the 1969 moon landing. The logic goes something like this:
Premise 1: If laws of earth-bound physics are obeyed on the moon, then spacecraft which we send there will behave as we predict, based upon earth-bound physics.
Premise 2: Our spacecraft behaved as we predicted (such as the Surveyor 1 spacecraft in 1966).
Conclusion: The laws of earth-bound physics are obeyed on the moon.
It should be immediately obvious that this argument is a classic example of affirming the consequent, a fallacy of propositional logic. In the above argument, we have extrapolated from one event (the Surveyor 1 spacecraft) to a generality. For some reason, Camp thinks an extrapolation here is "demonstrated by the evidence," even though it is logically fallacious, but he does not allow extrapolation in biology. As explained earlier, in his attack on extrapolation Camp is attacking all of science. In fact, if we deny science the right to extrapolation, we deprive science of the ability to make predictions and conclusions. If we allow extrapolation, we simply cannot claim that scientific conclusions are proven. This does not mean, however, that science cannot approximate reality and make useful predictions and explanations, as it obviously does. In practice, scientists use probability and statistics to quantify the degree of support that evidence provides for a given hypothesis or theory. In sum, since nothing can be proven in science, and all is extrapolation, Camp is not "pointing out the difference between what is extrapolated or assumed and what is proved" - he is attacking the scientific practice of extrapolation, plain and simple. Mr. Camp's philosophical and theological bias allows him to ignore extrapolation in any science except biology.
Camp ends here on a strange note by adhering to only birds, reptiles, and mammals. The prediction being criticized was the general prediction from common descent of transitional forms. The bird-reptile transitional forms (such as Archaeopteryx and the various wingless feathered dinosaurs recently found in China) that Camp mentions are only a small minority of the numerous transitional forms found in the fossil record. All of these intermediates linking the grand swath of living and extinct organisms certainly do offer strong support for universal common descent when taken as a whole.
Camp correctly restates the prediction and then begins his criticism in earnest:
There is nothing about the hypothesis of universal common ancestry that requires organisms to have descended in the pattern depicted in the standard phylogeny. ... A phylogeny is simply a depiction of the order in which evolutionists believe taxa arose, not the order in which they were required to arise.
Camp has it backwards. Cladistic phylogenies are built based upon morphology. The order in which organisms arose is a deduction from a phylogeny. Thus, whenever we have a well-supported phylogeny, the order in which organisms are required to have arisen is firmly predicted, based upon that phylogeny. Camp directly contradicts himself in the next paragraph:
... ancestral taxa must have existed before any taxa that descended from them ...
Yes, and that is exactly why a phylogeny predicts the relative order in which taxa have arisen during evolution.
Camp has responded to this:
... one cannot predict from universal common ancestry that intermediates will appear as reflected in the standard phylogeny. That prediction must be rooted elsewhere than in the bare hypothesis of universal common ancestry. ... the expectation that organisms will appear in a particular order is not a deduction from universal common ancestry; it arises from a phylogeny. Thus, the hypothesis of universal common ancestry would not be proven false by the discovery of a fossil "intermediate" out of the order reflected in the standard phylogeny.
Here Camp is still confused and again misrepresents evolutionary theory. The standard phylogeny is the rigorous scientific depiction of universal common descent; they are one and the same. The reasoning is very simple: common descent is the hypothesis that all living species are genealogically related, and everything that is related has a genealogy. A genealogy of species is a phylogeny, and thus the genealogy of all species is the standard phylogeny. Since organisms must have arisen in the order depicted in a phylogeny, the order of evolution of all organisms is a deduction from common descent. Anti-evolutionists can plug their ears and squeeze their eyes shut, yet the science still remains.
Failing to grasp the point, Dr. Theobald accuses me of contradicting myself in the very next paragraph because I acknowledged the truism that ancestors must have existed before descendants.
Camp contradicts himself because he fails to grasp the truism that the standard phylogeny is equivalent to a specification of universal common descent on our planet.
... it remains possible for a proponent of common descent to assert that select taxa appear in the fossil record contrary to the order in which they came into existence.
Witness the fact dromaeosaurids, which are offered by Dr. Theobald as "reptile-bird intermediates," first appear in the fossil record some 25 million years after the first fossil bird. ... Rather than disqualifying dromaeosaurids in Dr. Theobald's eyes as "reptile-bird intermediates," which he argues must appear in the order suggested by the standard phylogeny, it is simply assumed that dromaeosaurids lived tens of millions of years before there is any evidence of their existence. (The ambiguity of "general chronological order" prevents such nonconformities from falsifying the claim.)
The issue of "out-of-order" fossils has been addressed thoroughly in the updated version of Prediction 5. If we consider the entire geological record of the earth, an uncertainty of 25 million years is equivalent to less than 0.6% relative uncertainty. If we consider only the fossil record of life, an error of 25 million years is equivalent to, at most, a 1% relative uncertainty. Both values are overall quite minor. In fact, we know empirically that the error inherent in the fossil record is worse than that. For example, the coelacanth last appeared in the fossil record 80 million years ago, yet it is alive today. Thus, arguing that certain fossils are "out-of-order" by merely 25 million years is a meaningless argument. It carries no scientific weight. In contrast, the finding that these fossils were "out-of-order" by, say, 150 million years would be much more significant, since the resolution of the fossil record is known to be better than that in most cases (especially throughout the Mesozoic and Cenozoic).
The assertion that "The ambiguity of 'general chronological order' prevents such nonconformities from falsifying the claim [of prediction 5]" is incorrect. There are very well defined scientific statistical methods for determining whether the chronological order of fossils generally matches the order required by the consensus phylogenies. If stratigraphy generally matches phylogeny, then there is a positive correlation between stratigraphic position and phylogenetic rank. It is also possible to demonstrate that there is either no correlation between phylogeny and stratigraphy or that there is an anti-correlation. Demonstrating a statistically significant negative correlation between the standard phylogenetic tree and the fossil sequence would be a firm falsification of this basic macroevolutionary prediction. However, as detailed in Prediction 5, there is overall a statistically significant positive correlation between stratigraphy and phylogeny, which is a strong confirmation of the prediction that "fossilized intermediates should appear in the correct general chronological order based on the standard phylogenetic tree."
The fact synapsids appear before dromaeosaurids hardly constitutes proof (confirms the "prediction") that "fossilized intermediates" appear in the general chronological order indicated in the standard phylogeny. They are only two data points.
True, but they were only given as representative examples, not as sole "proof." Furthermore, these two data points are very well-supported phylogenetically, and their temporal separation (~150 million years) is outside the likely error of the fossil record.
But more importantly, one must bear in mind that Figure 1 is of necessity a simplified and fragmentary phylogeny. The picture changes significantly when the scope of inquiry is broadened. According to one Harvard-trained paleontologist:
"[T]he correspondence between phylogeny and the fossil record is not as strong as it might first seem. When the order of all kingdoms, phyla and classes is compared with the most reasonable phylogenies, over 95 percent of all the lines are not consistent with the order in the fossil record." (Wise 1994, p. 225-226.)
Again, Camp is quite mistaken. The quote from Kurt Wise is supported by opinion only, not by facts or by any published analysis of the data. In reality, the more diverse the taxa that are included in the analysis, the stronger the correlation between stratigraphy and phylogeny, and the more statistically significant it becomes. For many relevant references, see the "Confirmation" of Prediction 5.
Camp has replied:
That is true, but it does not alter the fact Wise performed the analysis and reached the quoted conclusion.
Actually, we have no evidence that Wise performed the analysis. We can take Wise's word for it (and in fact I do), but most importantly we have no reason to believe that Wise's analysis is correct. That is exactly why science is fundamentally dependent upon peer review - other scientists need to evaluate the data and double check the methods and conclusions of any scientific analysis. It is quite common for even respectable, intelligent, well-meaning scientists to make mistakes. As might be expected, anti-evolutionists (especially the "scientific" creationists") are not fond of peer review.
Dr. Theobald then gives the impression that Wise's conclusion is contradicted by a dozen studies referenced in the "Confirmation" section of Prediction 5 of his revised article. That, however, is incorrect.
In fact, that "impression" is quite correct, and it is based on numerous published analyses from many different researchers.
None of those studies duplicated Wise's analysis. That is, they did not compare the order of all kingdoms, phyla, and classes with their most reasonable phylogenies. Rather, they took multiple cladograms of a narrower range of taxa and compared them with the fossil record for those groups.
These statements are ludicrous. Wise's analysis has never been published; how does Camp know what Wise did?
Moreover, the results are not as impressive as one might think from Dr. Theobald's comments.
Camp then goes on to list specific data from some of the referenced published papers which demonstrate a highly significant correlation between stratigraphic order and phylogeny. Camp erroneously believes it is problematic that a minority of single cladograms show no correlation with stratigraphic data. If this were true of scientific theories, then the fact that smoking causes cancer would be falsified, since many people who smoke do not develop cancer. But science does not work that way. All physical processes involve stochastic (chance) elements, and scientific results are evaluated statistically. Camp conveniently omits the statistical analyses which demonstrate exactly how impressive the total data really are. For instance, Michael Benton and Rebecca Hitchin published a recent, greatly expanded, and detailed stratigraphic analysis of 384 published cladograms of various multicellular organisms (Benton and Hitchin 1997). Using the three measures of congruence between the fossil record and phylogeny mentioned by Camp (the RCI, GER, and SCI), these researchers observed values "skewed so far from a normal distribution [i.e. randomness] that they provide evidence for strong congruence of the two datasets [fossils and cladograms]." The results were overall extremely statistically significant (P < 0.0005), a result that is extremely impressive. As the authors comment in their discussion:
"... the RCI and SCI metrics showed impressive left-skewing; the majority of cladograms tested show good congruence between cladistic and stratigraphic information. Cladists and stratigraphers may breathe easy: the cladistic method appears, on the whole, to be finding phylogenies that may be close to the true phylogeny of life, and the sequence of fossils in the rocks is not misleading. ... it would be hard to explain why the independent evidence of the stratigraphic occurrence of fossils and the patterns of cladograms should show such striking levels of congruence if the fossil record and the cladistic method were hopelessly misleading." (Benton and Hitchin 1997, p. 889)
In sum, the chronological appearance of fossils in the fossil record generally matches very well with the order required by the consensus phylogeny of the major taxa. Although it was possible to falsify this prediction, this prediction has been confirmed and offers strong support for the theory of common descent.
Camp's criticism of Section 1 of the "29 Evidences" was nearly twice as long as Section 1 itself; my response to Camp's criticism of Section 1 is nearly three times as long as the original Section 1. The remaining four sections will have to wait. I have read them, and they are more of the same. None are difficult to rebut. As stated at the beginning of this rebuttal, Camp's critique is error-ridden in various ways, and is plagued by this "host of intellectual sins" (in Camp's own words):
Each of these "tactics" resurfaces in the remaining four sections of the critique. It should be obvious from even this limited rebuttal that Camp's criticism of the "29 Evidences" is without any scientific merit.
Camp concludes his article with this claim for his motivation:
Dr. Theobald [is] certain that the evidence of nature points ineluctably to the conclusion of universal common ancestry. I once shared that opinion of history, but having shifted my point of view, I find that the same evidence points to something entirely different.
What is this "something entirely different"? From the second sentence of Camp's critique:
I believe the founding members of these groups [of organisms] were created miraculously and separately by God.
There is good reason to be skeptical of the claim that Camp was led to this conclusion by the "evidence of nature." Camp has written elsewhere that his rejection of evolutionary theory is not based in scientific evidence, but rather it is a result of a religious conviction to a literal interpretation of Genesis.
"[Scripture] cannot contain errors or falsehoods. Everything in it must be true ... " (Camp 1999, p. 20-21)
"I sympathize with the desire to present Scripture as compatible with current scientific orthodoxy, but the exegetical objections to this theory strike me as insurmountable. ... All such interpretations strike me as attempts to conform the Bible to conclusions drawn elsewhere ... If the meaning of Scripture is distorted to fit scientific opinion, its authority has been relinquished. ... This is not to deny that it is difficult at present to harmonize some of the scientific data with a recent-creation interpretation of Scripture." (Camp 1999, p. 42-43)
It is also difficult to reconcile Camp's statement that "I find that the same evidence points to something entirely different" with "it is difficult at present to harmonize some of the scientific data with a recent-creation interpretation of Scripture."
Perhaps, then, even Mr. Camp agrees that his critique is not based in
1. As an aside, Camp has misplaced the above Denton quote. To be fair, Denton made that remark in response to the controversial "molecular clock" hypothesis, which is related though distinctly different from the observation of equal molecular divergences between species. From his later comments, Camp evidently does not understand this difference. The molecular clock hypothesis is the idea that rates of evolution are constant throughout time. Rates could be extremely variable yet result in equal genetic distance between two species serendipitously. Conversely, rates could be very constant in specific lineages, yet result in unequal genetic distances (if the rates are unequal between lineages). Regardless, Denton is still confused on the subject, as he uncritically assumes that absolute background mutation rates in yeast should be "100,000 times greater than in a tree or a mammal ..." (Denton 1998, p. 291-292). This would only be true if DNA replication errors were the primary source of mutations. However, there is currently little data supporting this directly. Recent studies have indicated that other sources of mutation are more important (Huttely et al. 2000; Bohossian et al. 2000; Kumar and Subramanian 2002). All else equal, we expect that absolute background mutation rates should be equivalent between species, and that is roughly what is observed. Even if DNA replication errors are the primary cause of mutations, from the most basic conclusions of neutral theory there are other reasons (beyond the scope of this rebuttal) for why rates of protein evolution should be relatively equal between organisms with very short or very long generation times (see Ohta 1993 and references therein - this article gives the consensus explanation which Denton claims does not exist, and it demonstrates that the evidence supports this explanation). Back
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