Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
2 online now:
Newest Member: popoi
Post Volume: Total: 915,817 Year: 3,074/9,624 Month: 919/1,588 Week: 102/223 Day: 13/17 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Opponents of Evolution Adopting a New Strategy
BeagleBob
Member (Idle past 5677 days)
Posts: 81
Joined: 11-21-2007


Message 83 of 177 (470312)
06-10-2008 4:23 PM
Reply to: Message 78 by Wumpini
06-10-2008 3:23 PM


Re: New and Improved List - Maybe
Hi, I'm a geneticist and biochemist, with academic experience in neurology. I'll try to answer your concerns as best I can. I'll try to focus on a few key points on each individual section over time though, because quite frankly I dislike spaghetti logic.
quote:
Origin of Life Weaknesses:
I think it's very important to remember that knowledge of abiogenesis is not necessary to support knowledge of evolution. The two are as different as farming and cooking: one doesn't need to know the exact methods of planting, nurturing, or harvesting food at all to be able to cook with skill. The development of the raw materials (farming/abiogenesis) for a method is entirely different from the mechanisms of that method itself (cooking/evolution).
quote:
*The extreme improbability of obtaining any specific amino acid sequence needed for the proteins of life systems.
Unfortunately, the idea that "for a protein to work it has to have a specific sequence of amino acids" is a common misconception. Only a few amino acids (like glycine and cysteine) have unique functionality that might (though not always) drastically affect the protein if replaced. What's more important in general is that some amino acids are "watery" (hydrophilic) and others are "oily" (hydrophobic). It's the arrangement of hydrophilic and hydrophobic amino acids that matters, not the actual sequence of specific amino acids.
If you look at the sequence for hemoglobin between different species for example, you'd see some pretty significant differences in amino acid sequence. However, the resulting proteins look the same and act the same, to the extent that often you can use genetics to exchange the genes for these proteins between species with little to no effect.
quote:
*No known way to achieve 100% left-handed amino acids in proteins or the 100% right-handed sugars in RNA and DNA - all of which are universal to life systems.
*All natural processes are known to produce a 50-50% mixture of left-handed and right-handed molecules.
I think the website you got this from really should remove this point soon. Just recently a study made headlines when it was discovered that certain frequencies of polarized light preferentially destroyed right-handed amino acids. So while the amino acids might be produced in equal quantities, they are preferentially selected out.
Here's a link:
http://www.world-science.net/othernews/080406_chirality.htm
quote:
*There is no known natural source of the information that is present in all life systems. Random processes are never known to produce information.
Oof. The term "information" here unfortunately has a very vague definition. Generally when laymen talk about "information" we refer to bits of data, words, books, and whatnot. However, scientists that refer to "information" might speak of intelligent data, but on the other hand can speak of perfectly natural physical laws and properties.
For example, an ice crystal has a great deal of organized "information" that allows it to behave the way it does. Other chemicals have "information" in terms of its arrangements of valence electrons and intramolecular forces that allow certain reactions to take place. Biological chemicals are much the same in terms of "information," the only difference is they're a bit more complex.
At best this is an argument via analogy, at worst it's using a nebulous term to try to prove something specific.

This message is a reply to:
 Message 78 by Wumpini, posted 06-10-2008 3:23 PM Wumpini has replied

Replies to this message:
 Message 95 by Wumpini, posted 06-11-2008 3:06 PM BeagleBob has replied

BeagleBob
Member (Idle past 5677 days)
Posts: 81
Joined: 11-21-2007


Message 135 of 177 (470808)
06-12-2008 7:40 PM
Reply to: Message 95 by Wumpini
06-11-2008 3:06 PM


Re: Origin of Life "Weaknesses"
Wumpini:
Focusing on one particular topic is my preference. In fact, that should ideally be the purpose of individual threads. So in favor of shifting to a particular point of contention, I'd say it does sound like a good idea to focus on the issue you'd prefer (though I'm a bit miffed that the discussion has strayed so far from the original post).
I apologize in advance for the megapost, but to be fair it's a fair return on your investment.
.
.
.
quote:
I am not sure that all of these textbook authors understand that abiogenesis is not part of evolution. It seems that those on this website want to move abiogenesis as far away from biological evolution as they possibly can. I have seen discussions on other forums where the word evolution has been discussed. It obviously has a broad meaning and a narrow meaning. The broad meaning would include abiogenesis while the narrow meaning would only include biological evolution. It seems that textbook writers (in the textbooks I am looking at) include abiogenesis as part of the section that teaches evolution. In fact abiogenesis (chemical evolution) fits right into the theory of evolution. You must have life for anything to evolve, and evolution does not begin with complex organisms but with these simple single cell organisms. I have two college level textbooks that teach abiogenesis in two different ways but both are considered under the topic headings of evolution.
For evolutionary biologists, "evolution" refers specifically to the change in a biological population ("biological" = creatures made of cells, derived from Cell Theory) due to genetic changes. If there are no genes (such as with biological chemicals) biologists aren't talking about evolution.
The real boundary line in this matter would be viruses. Most wouldn't consider viruses to be a form of life because of their acellular, parasitic nature. However, since viruses do have genes they can be considered to "evolve." Most biologists would really say this is the outer edge of the science of "Evolutionary Biology."
Again, because evolution is (primarily) a genetic field, pre-genetic precursors fall more into the field of biochemistry. I agree that evolution and abiogenesis are both important fields for biology in general, refuting one doesn't refute the other. Just because we don't have a clear picture of abiogenesis doesn't mean we don't have a clear picture of evolution. This sort of argument is a guilt by association argument.
.
.
.
quote:
Here is an example of how one college textbook organizes their book. “Life: the Science of Biology” by Purves, Sadava, Orians, Heller:
Oh examples are unnecessary. I'm quite sure that there is at least some mention of abiogenesis in science textbooks.
It's quite common to see this sort of thing in textbooks that address general fields. For example, a textbook on world history will often start off with the creation myths of a particular society. On a chapter titled "Japanese History," for example, I've seen prologues start off with the story of how the male and female gods were said to have made the island of Japan.
Looking at the examples you provided, this seems to be something similar, since no more than two or three pages appear to be devoted to abiogenesis. It's a sad fact that textbooks which deal with a general view of a subject tend to lack rigor and specifics, but this shouldn't reflect the science as a whole.
It's also important to note that in textbooks (especially general-topic ones) chapters tend to merge things that have a similar topic, even if the scientific details are wholly unrelated. While evolution and abiogenesis are similar topicwise (the origin and development of life), the details differ entirely (a matter of genetics and development versus chemistry and biochemistry).
Again, remember that the chemical details of life's origins are unrelated to the biological developments that occur when existing life is there. This is much like how the agricultural details of farming are unrelated to culinary excercise when the ingredients are already there. Bobby flay may not know how to grow the perfect tomato, but this ignorance doesn't mean his knowledge as a chef is deficient.
.
.
.
quote:
You are the expert in this field, so I will rely upon your input. Is it not true that it is improbable that these proteins will fold in the proper shape and with the proper function without a specified amino acid sequence? Here is a quote that kind of describes this process in layman’s terms.
(wikipedia quote)
There are certainly instances of point mutations that cause large changes to a protein's structure and function. However, these errors tend to be quite a bit rarer than neutral mutations. This is due to several reasons:
1. The genetic code is redundant, and in many instances (perhaps one third to two thirds of the time, I don't feel like crunching the numbers right now), a point mutation won't change the resulting amino acid sequence at all.
2. Much of the protein fold isn't determined by the specific identity of the amino acids, but rather by how polar or nonpolar they are. Thus, a sequence that says "MFPST" would most likely have the same structure and fuction as a sequence "FFPYT" (both have a +++-- pattern, where + is nonpolar and - is polar).
This second point is particularly significant, since specific proteins are very similar across species in shape and function, but often have quite a few differences in amino acid sequence. For example, if you replaced all the hemoglobin of a rabbit with all the hemoglobin of a human with genetics, the rabbit wouldn't really suffer any strange effects. They did this recently with the Apo-AIM protein in rabbits, intriguingly enough. No ill effects.
But yes, single-point genetic changes CAN influence protein shape and function, for two main reasons that I can think of right now:
1. If a polar amino acid is switched out with a nonpolar one in a critical region. (such as in Sickle Cell Anemia)
2. If an amino acid with a unique function (like glycine or cysteine) is replaced, but these are only 2 amino acids out of 20. (such as in the Apo-AIM mutation which actually improved protein efficiency)
quote:
Now I want to ask you honestly. If we are going to teach children that this is a scientific fact, don’t you think we ought to point out that there are a few “weaknesses” in the hypothesis?
The rest of your post seems to be concerned with whether abiogenesis is being taught in schools, and you point out that if it is taught, the weaknesses of the hypotheses should be taught as well.
I agree. In fact, I'm not sure we should teach abiogenesis in high schools at all, personally. At best it should be given glossed over. High school is for teaching fundamentals that are very well-established. College is where you learn about hypotheses which are under review.
Until a solid theory of abiogenesis is developed, I think high schools should instead be focusing on the more robust and well-proven facts and the theory of evolution. If students want to hash out the details of abiogenesis, they can do that in college.
I'm a little annoyed that the textbooks you listed do have sections on abiogenesis, but such is the nature of introductory sections of textbook chapters. It's not a problem unique to biology textbooks.
Edited by BeagleBob, : Added a few details on the genetic mutations part, corrected last paragraph of post.

This message is a reply to:
 Message 95 by Wumpini, posted 06-11-2008 3:06 PM Wumpini has not replied

BeagleBob
Member (Idle past 5677 days)
Posts: 81
Joined: 11-21-2007


Message 137 of 177 (470812)
06-12-2008 7:52 PM
Reply to: Message 136 by Wumpini
06-12-2008 7:41 PM


Re: Definition of Weakness
quote:
I have found a list where these folks have proposed that they want textbooks to include additional information related to these areas where they feel that science is weak. In other words, they want the students to know that scientists do not have all the answers. Now you seem to be telling me that I should focus my discussion on areas where there are no questions. Do you not see a little contradiction in that line of thought?
Kids should be taught that no authority at all has all the answers. However, this paradigm should be used to correct our educational system as a whole. Singling out evolution as a topic of contention in this matter is too narrow a perspective.
Incidentally, I would agree that genuine criticism on a field as a whole should focus on its more centralized themes. After all, we don't judge Christianity as a whole by looking at kooks like Fred Phelps or by erroneous theology like what stemmed from St. Aquinas.
This really a problem with the Discovery Institute and the ICR. They level criticism at ideas that are peripheral to the central theme and think that this would defeat evolution as a whole.
You can't cut down a tree by trimming a few leaves. You have to get at its roots.
Whoops, I gotta get back to the lab. I'll try looking over the rest of your post later.

This message is a reply to:
 Message 136 by Wumpini, posted 06-12-2008 7:41 PM Wumpini has not replied

BeagleBob
Member (Idle past 5677 days)
Posts: 81
Joined: 11-21-2007


Message 151 of 177 (470999)
06-13-2008 9:34 PM
Reply to: Message 150 by Wumpini
06-13-2008 7:47 PM


Re: Moving into the fossil record
Wumpini:
Can you please provide the source you're citing here? I'd like to look it over.
EDIT: Whoops, I meant to reply to message # 149
Edited by BeagleBob, : No reason given.

This message is a reply to:
 Message 150 by Wumpini, posted 06-13-2008 7:47 PM Wumpini has not replied

Replies to this message:
 Message 152 by RAZD, posted 06-13-2008 10:28 PM BeagleBob has not replied

BeagleBob
Member (Idle past 5677 days)
Posts: 81
Joined: 11-21-2007


Message 156 of 177 (471140)
06-15-2008 4:34 AM
Reply to: Message 149 by Wumpini
06-13-2008 5:59 PM


Re: The Cambrian Explosion
Wumpini:
Hmmm. I do wish I could've seen the original source you're citing. Your message is a bit long, so I'm going to focus on the general, central points you seem to be making from the data you're presenting.
.
.
"We should include more about the Cambrian Explosion in our textbooks. Kids NEED to learn about this event and we shouldn't gloss over it."
I agree absolutely. Without a doubt, I think it's fair to say that the Cambrian Explosion is a landmark event in the history of the earth and it's appalling that so many textbooks give it short shrift. There needs to be more focus on this event and the reasons behind what occured, as I detail in the next section.
.
.
"Evolution is hard-pressed to explain the Cambrian Explosion. It is far too rapid/huge an event for natural selection to account for."
There are a couple of things people usually don't take into account when they talk about the Cambrian Explosion. The first is ecological in nature, the second is biological, the third paleontological. But before I get to that, I have to say that it's very important to remember that depending on the conditions, evolution can occur at very very different rates. Sometimes it can be fast, sometimes it can be slow, and this depends the ecology and the nature of environmental stress.
Ecological Factor: Now, I was a child of the '90s and it was a real boistrous, amazing time for technology. The internet had just been getting off the ground and this new medium had opened up for people to expand and explore businesswise.
If you lived during this time, you might remember EVERYONE was trying to create an internet business. There were businesses online that would ship groceries, businesses that would ship pet products. There were businesses for pastry enthusiasts, gardeners, just about everything. People were wildly optimistic about the Dot Com Boom, and for several years it was a period of HUGE economic growth. However, because we didn't know about the realistic limitations of the new technology, we didn't know which business models would best survive and which ones wouldn't. This resulted in the dot com crash in 2001-2003, where a large amount of businesses failed horribly. Here's a graph of the Nasdaq ratings:
We see this happening all the time. Once a new industrial model opens up people go buck wild, invest a great deal into hundreds of branches in that model, and eventually the economy collapses when the businesses that are poorly fit for the industry go bankrupt. Another example would be Holland and the tulip debacle... a favorite of mine ever since I read about it as a kid.
This is the exact same thing that happened with the Cambrian Explosion. Because life was first starting out on earth there were many ecological niches that were unfilled. Life bloomed very rapidly, branched out at an amazing rate as nature experimented with countless forms, and eventually the animal forms that are most fit out-compete the less-fit ones and a huge extinction event is the result. Perfectly consistent with our observations of the Cambrian Explosion.
Biological Factor: It's also important to remember that most animals in the early Cambrian were soft, squishy critters that aren't very durable. When skeletal structures do develop, there's definitely going to be a massive surve in evolutionary rates. Predators have to evolve harder, stronger teeth to get through armor, and armor has to thicken to protect the animal from harm. This arms race would produce two effects: first, an escalation of evolutionary rates as each species has to out-compete others. The second reason leads us to the third factor:
Paleontological Factor: As I've mentioned, primitive critters (especially early cambrian ones that were often spongey or jelly-like) just don't fossilize well.
The low number of fossils before the Cambrian explosion isn't a sign that there were no animals back then and that all these forms appeared ex nihilo as Creationists seem to think. Instead, this was just a period when reliable fossilization had only just started, in a time when evolutionary rates were very high due to vast environmental opportunity and novel biological competition. This leads us to the third point in your post:
.
.
"The fossil record does not fit the traditional model of phyletic gradualism, or the model of punctuated equilibrium."
Well of course the fossil record of the Cambrian Explosion doesn't fit evolutionary models. That's because the fossil record had only become relatively reliable when animals first developed hard structures that can fossilize easily at this time.
This criticism is like saying "These computer records that date back from the 1970s are an incomplete record of the company." Well of course they are... computers had only come into wider use in the 80s, and of course the records are going to be spotty back then.
The fossil record isn't the be-all and end-all of life on earth... if there are holes in the evidence it's the fault of how nature works, not the fault of the theory or of the science of evolution.

This message is a reply to:
 Message 149 by Wumpini, posted 06-13-2008 5:59 PM Wumpini has replied

Replies to this message:
 Message 157 by Minnemooseus, posted 06-15-2008 4:53 AM BeagleBob has not replied
 Message 161 by Wumpini, posted 06-15-2008 6:57 PM BeagleBob has replied

BeagleBob
Member (Idle past 5677 days)
Posts: 81
Joined: 11-21-2007


Message 162 of 177 (471262)
06-15-2008 7:19 PM
Reply to: Message 161 by Wumpini
06-15-2008 6:57 PM


Re: The Cambrian Explosion
Wumpini,
Sorry I didn't see those links earlier. I had typed up the message during that huge length of time the forums were down and posted it before seeing if you'd corrected the post.
There are two things that need to be distinguished here: the evidence and the theory.
Without a doubt there are holes in the evidence. If every living creature had become fossilized postmortem and they became deposited with a bunch of substrates that can be used for reliable radiometric dating, we wouldn't be having this discussion. But then again, I might as well wish for flying cars, moon bases, and a 2-year extension to my research contract while I'm at it along with a hot undergraduate assistant (don't worry, I'm 24 it's totally not creepy).
However, there are no holes in the theory of evolution itself. The theory is wonderfully and amazingly complete after nearly 150 years, and it can certainly explain our observations of the Cambrian Explosion. You just need to pull together ecological knowledge and biological data from other fields to supplement those holes in the evidence and come back with a complete picture. Science is a mosaic structure. Heck, this is why evolution is categorized under the Integrative Biology department back in Berkeley.
I believe that the Cambrian Explosion should be taught in a comprehensive manner that gives students an understanding of the bigger picture of science, and that requires a lesson on how other evidence is used to supplement the fossil record. A lesson on just the "weaknesses" and "holes" would serve our students poorly... it'd be like teaching an aspiring cook that it's impossible to bake cookies without butter when you have a perfectly good stick of margarine on the counter.
Edited by BeagleBob, : Bolded some words.

This message is a reply to:
 Message 161 by Wumpini, posted 06-15-2008 6:57 PM Wumpini has not replied

Replies to this message:
 Message 163 by randman, posted 06-15-2008 7:22 PM BeagleBob has not replied
 Message 164 by BeagleBob, posted 06-15-2008 7:29 PM BeagleBob has not replied

BeagleBob
Member (Idle past 5677 days)
Posts: 81
Joined: 11-21-2007


Message 164 of 177 (471264)
06-15-2008 7:29 PM
Reply to: Message 162 by BeagleBob
06-15-2008 7:19 PM


Re: The Cambrian Explosion
Wumpini,
I'm personally a big fan of detective shows, like Monk and Law & Order SVU. While admittedly it's more a love of raunchy plotlines the investigative part is also really nifty.
When investigating anything, be it science or forensics, there is rarely a single clear line of evidence that points to a conclusion (or suspect). You have to use multiple bits of smaller pieces of evidence to tie together an explanation of what occurred. With enough evidence, even if each individual element is incomplete, the resulting quilt is a pretty clear picture of what happened.
I should add that this is why I feel that the approach of Wells, Dembski, and others who want to "teach the controversy" is rather disingenuous. Just because there are some holes in one particular line of evidence doesn't mean that they can't be patched with lines of evidence from other sources. This is how science as a whole is done, and picking on evolution specifically is more a sign of an agenda than one of honest inquiry.
EDIT:
quote:
quote:
If every living creature had become fossilized postmortem and they became deposited with a bunch of substrates that can be used for reliable radiometric dating, we wouldn't be having this discussion.
Why do you say that?
I'd think it's pretty obvious that if the fossil record was entirely complete with plenty of substrates for radiometric dating, people wouldn't be speculating about the supposed "weaknesses" of evolution in the first place
Edited by BeagleBob, : Responding to randman

This message is a reply to:
 Message 162 by BeagleBob, posted 06-15-2008 7:19 PM BeagleBob has not replied

Replies to this message:
 Message 165 by Coyote, posted 06-15-2008 7:39 PM BeagleBob has not replied

BeagleBob
Member (Idle past 5677 days)
Posts: 81
Joined: 11-21-2007


Message 167 of 177 (471272)
06-15-2008 8:14 PM
Reply to: Message 166 by Wumpini
06-15-2008 7:57 PM


Re: The Cambrian Explosion
quote:
You are entirely correct. Both the “phyletic gradualism” and the “punctuated equilibrium” trees should show these “deepest taxonomic divisions” coming into existence suddenly during the Cambrian explosion. The problem is that neither theory explains why these divisions come into existence in the first place. That is the point! It is a major unanswered question! It should be taught as such.
I wouldn't say this question is unanswered... I provided an answer under Message 156, under the Ecological section of the second question.

This message is a reply to:
 Message 166 by Wumpini, posted 06-15-2008 7:57 PM Wumpini has replied

Replies to this message:
 Message 168 by Wumpini, posted 06-15-2008 10:01 PM BeagleBob has replied

BeagleBob
Member (Idle past 5677 days)
Posts: 81
Joined: 11-21-2007


Message 169 of 177 (471308)
06-15-2008 10:52 PM
Reply to: Message 168 by Wumpini
06-15-2008 10:01 PM


Re: The Cambrian Explosion
quote:
Do you notice what he says? "We do not know why ..." You may say that you know why, but other scientists say they do not know why. They are examining the same evidence (or lack of evidence) and trying to use the same arguments. Therefore, I conclude that this question is unanswered.
It's important to remember that the Cambrian Explosion is a very complex event, and there were likely many factors involved. I only listed three (the filling of niches, predation, and the development of bony structures in fossilization) but there are lots of other factors: hox genes, climate change, etc. However, the main issues of niche-filling and predation is still central to most explanations of the Cambrian Explosion as I've seen. Even though it's not a complete picture, I feel that this is the best point to focus on in public education since the genetic and climate details are harder to frame in a pedagogical setting.
Let's go back to the main premise of the original article you cited, that we should "teach the controversy because evolution isn't all that it's cracked up to be." Lists like that and "Ten Questions to ask your Biology Teacher" center on an oversimplified view of the Cambrian Explosion, and utterly ignore the fact that very strong explanations exist to explain our observations.
It's fine to talk about the limitations of our knowledge, but this shouldn't be done in order to imply that scientists are wholly ignorant on the issue, or to imply that lack of knowledge on some details of evidence implies major problems or gaps in the theory behind it. It's tendentious to do so, and it's very dishonest on the part of Wells & Company.
EDIT:
quote:
I think we are in agreement Beagle. You have stated that "the fossil record of the Cambrian explosion doesn't fit evolutionary models." I agree. All I want is for high school students to be informed about what we have discussed on this forum. The only way we can be sure of that is to include this information in high school biology textbooks. We need to teach students the facts about the Cambrian explosion. The divisions appeared suddenly, the fossil record is not complete, and it does not fit into the current evolutionary model.
The problem is that statements like this imply that holes in evidence entail a deficiency in the theory (which is the point of the original article). This simply isn't the case: yes, the fossil record is incomplete, but this is primarily because the fossil record had only become reliable during the Cambrian, when bony structures were first developing (though elements that speed the rate of evolution is also a factor here).
This is what should be included in textbooks and lesson plans. It shouldn't stop at something fallacious like "The fossil record is incomplete, we don't know why, so evolution as a theory is incomplete."
Edited by BeagleBob, : No reason given.
Edited by BeagleBob, : No reason given.

This message is a reply to:
 Message 168 by Wumpini, posted 06-15-2008 10:01 PM Wumpini has not replied

BeagleBob
Member (Idle past 5677 days)
Posts: 81
Joined: 11-21-2007


Message 172 of 177 (471419)
06-16-2008 6:43 PM
Reply to: Message 171 by Wumpini
06-16-2008 5:32 PM


Re: The Cambrian Explosion
quote:
The question is: should high school students be made aware of the evidence that exists or does not exist in the fossil record to support the theory of evolution as it relates to the Cambrian explosion? Do you not think we should teach students what exists and does not exist in the fossil record?
I don’t believe that the “strengths and weaknesses” people are saying that science should not teach the different hypotheses regarding how this great disparity of life came into being. They are only saying that if you are going to teach that this fits into traditional evolutionary theory, then you need to teach that there is no evidence in the fossil record to support that statement.
Let's frame this in an example:
Creationists often argue that C14 radiometric dating can't prove that the world is 4.5 billion years old. They'll also say that there are problems with C14 dating because dating a live clam would give a result of the sample being 30,000 years old.
These points are true. However, they are also misleading. First, the upper range of C14 dating is about 50,000 years at most... if you want to date a rock layer that you suspect is in the billions of years range, you'd need Uranium-Lead dating. Second, C14 isn't meant to analyze animals that live in an aquatic or marine trophic chain, so of course C14 would give you an anomalous date. In fact, biologists take advantage of this to determine the diets of our ancestors, seeing how much of their food came from the land and how much came from the sea.
Teaching our kids that "C14 dating can't prove the world is 4.5 billion years old and C14 testing of live clams would give you crazy dates" is true, but it's done with the intent to mislead children. Without context it's an attempt to lead kids to the conclusion that "C14 dating can't be used at all."
The same problem exists for the Cambrian Explosion points on the list you posted earlier.
Technically it's true that much of the fossil record for the Cambrian Explosion doesn't support conventional models of evolutionary progress... but saying this alone, divorced from the broader scientific reality, is disingenuous. The idea that "the fossil record doesn't explain the Cambrian Explosion" alone shouldn't be what's taught, but instead what should be taught is the wealth of other observation and understanding.
I think this is the real problem with these points of contention and "Ten Questions You Should Ask Your Biology Teacher" things that Intelligent Design proponents put out. They miss the forest for the trees.

This message is a reply to:
 Message 171 by Wumpini, posted 06-16-2008 5:32 PM Wumpini has replied

Replies to this message:
 Message 173 by Wumpini, posted 06-16-2008 9:02 PM BeagleBob has replied

BeagleBob
Member (Idle past 5677 days)
Posts: 81
Joined: 11-21-2007


Message 175 of 177 (471443)
06-16-2008 9:55 PM
Reply to: Message 173 by Wumpini
06-16-2008 9:02 PM


Re: Fossil Record - Point 2
quote:
Many life forms persist through large expanses of geologic time with essentially no change. Evolution theory suggests that mutations occur randomly over time and are selected to produce continuing change as the environment continually changes.
As we've seen from the Cambrian Explosion, evolution can occur at vastly different rates. Sometimes it can occur quickly, other times slowly, and sometimes organisms don't evolve very much at all.
Remember that evolution depends on two main factors: the first is the mutation, the second is environment. If an environment is in vast flux, or if the species is isolated, or if the environment is subject to very little change, you're going to see many different effects on the rates of evolution. Sometimes very fast, sometimes very slow, if at all. On the other hand, if a particular form is very well-adapted and successful, there may not be much of a need for an organism to evolve at all.
So really there should be no surprise that some species, such as sharks and crocodiles, have maintained relatively similar forms through a long period of time.
I don't think there's much else to say if the main premise is incorrect.
EDIT: What do you understand about punctuated equilibrium? It's a slightly abstract concept that is commonly misunderstood, so I don't quite know what you're getting at here.
Edited by BeagleBob, : Reason listed.

This message is a reply to:
 Message 173 by Wumpini, posted 06-16-2008 9:02 PM Wumpini has not replied

Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024