Proofs of Evolution: A Mediocre Debate (Faith, robinrohan and their invitees)

Hi Faith and robinrohan-Hopefully you don't mind me popping in to make this comment; I won't interfere otherwise - it seemed the offer was made: "Complexity" is a difficult thing to define/quantify, but evolution doesn't proceed from simple to complex, so it may be a non-issue given the context. Instead, evolution proceeds from "less fit" to "more fit" for a given species and environment.A well-studied example is the stickleback fishes - it appears that they have evolved to lose certain characteristics in certain environments - specifically armor plating and pelvic fins have been examined recently in great detail. The loss of these characteristics might appear to make the organisms more "simple", but the loss increases the organisms' "fitness", and thus its ability to survive, reproduce, and pass on its genes - in other words, pass "natural selection". I can provide references if you like, but they will be quite technical.Hopefully that was helpful and I didn't overstep any bounds - let me know if I did and I can delete some or all of the post. If it was helpful I'll try to answer other questions when I can.Good luck.

Did you still want a comment on me on this point? I don't want to derail the topic, since it has since seemed to go in a more genetic direction...

Faith/RR,First let me state that I am definitely not an expert on the fossil record, but I don't think you have to be to understand the concept behind the "complexity" levels found in different geological layers.First a couple of things-- I'm going to use "complexity" and "simple" as ambiguous, non-scientific terms, since that is what they are (once there was a thread to come up a quantitative scientific definition of "complexity" and we got nowhere in a couple of hundred posts...). My post will be in very generalized, layman's terms.- I'm going to be describing concepts based on the theory of evolution, so please do not counter with fossil sorting by the Great Flood or other Biblical references as a way to refute my description - that's for you two to sort out later (pun intended).To RR's question: To a certain general extent, yes - the older the geological layer, the simpler the organisms in the layer. However, this is an over-generalization, and it does not mean that evolution proceeds from simple to complex. It is still a matter of evolution proceeding from "less fit" to "more fit"; combined with the history of life starting out as simple (no where to go but up, or over).Besides the idea that life started out simple -when life first arose on Earth, the Earth was a very different place that would be very harsh to life as we see it today, and "simple" life was the "most fit" for such an environment. Think of the life we see today at hot thermal vents - they are teeming with bacteria, but you don't see any gophers setting up their homes in/around the vents for obvious reasons - at a thermal vent, bacteria are more fit than gophers, or humans, or just about anything else we see as "higher" organisms.Now imagine that the whole Earth was similar to a hot thermal vent - okay for pre-cell or single-cell organisms, bad for anything else. The environment needed to change to open up niches for more complex life, so that the complex life would be more fit than the simple life - the trend likely started because complexity increased fitness by giving organisms the ability to detect and/or actively gather nutrients in ways that their "simple" ancestors could not.But remember, evolution is a "bush" or "tree", not a straight line from simple to complex. On a "complexity" scale, evolution can go forwards, backwards, or laterally (change in character without overall change in complexity). When we look back at the history of life in the fossil record, it may seem that there is an almost linear increase from simple to complex, but it was always the case that even as "more complex" organisms were evolving, "more simple" organisms were evolving as well - all based on "fitness". It's just that the complexity of the most complex organism found in a given geological layer increases with increased time from the inception of life.This general trend of simplicity-to-complexity could reverse someday as the Earth's environment changes. If, for example, the temperature of the planet increases drastically, or the planet is bombarded by a new source of cosmic radiation, us "complex" creatures will suddenly be much less fit than "simple" organisms, and evolution will generally proceed from "complex" to "simple" organisms.Keep in mind that some of the most evolutionarily optimized and flexible organisms are single-celled, and that single-celled species dominate this planet. There is high fitness in requiring little resources and being able to live in varied environments.Hopefully that helped some - let me know if I can try to further explain.

Yes, it can be mutation.We know this because such spontaneous mutations are routinely observed in the lab, in controlled genetic stocks.Mouse geneticists use "inbred" strains of mice, which are homozygous at all loci - they have zero genetic variability within the strain, and are thus essentially clones of one another. To put it another way, all mice within the strain are genetically identical, except for spontaneous mutations that occur at each generation.These spontaneous mutations are enough of a problem that research mouse suppliers use various quality control measures, including freezing down large numbers of embryos of each strain, and thawing them out every several generations to reconsitute their stocks. If they didn't do this, the character of the inbred stocks would change over time, causing problems with reproducibility and controls. All of the quality control, including the cryogenic process and reconstitution, is a huge expense of time and money, but it is done to overcome the inescapable issue of mutation at every generation.In these incredibly controlled, homogeneous stocks, new coat colors and textures regularly pop up (as do other new characteristics). The arisal of new phenotypes is so common that scientists cannot even afford to maintain stocks of these novel mutations, let alone analyze them, so they are routinely "thrown away".One such documented case: after several hundred generations of black mice, two of these black mice give birth to a litter that contains several white mice. The gene and mutation is found that causes the white coats. The black parents of the white mice are both heterozygous for the white mutation. But none of the grandparents of the white mice carry the mutation. To restate: the grandchildren have an allele that the grandparents do not have; the source was mutation.I know the regularity of such mutation in part because I've observed it myself - I had a recessive mutation arise in my stock of black inbred mice that caused a white "belly spot" - it was a single gene effect based on inheritance.This message has been edited by pink sasquatch, 12-21-2005 10:44 AM

The fact that mutation will happen is predictable.Where and how it will happen is not, (despite some mutational biases).I simply answered your question: Novel mutation produces novel phenotypes.

Yes - I'm a bit confused about where both of you want my input. Faith seemed to say at one point that I should hop in at will - I'm trying to do so when specifically asked, or if I have background information for a specific point that you both seem unsure about. Sorry if I stepped over any bounds.I'm really just trying to be helpful and don't want to derail your thread or take away steam from either side; I think I'll wait until I see my name and a question mark to enter the discussion again...

Faith misunderstood my posts to a significant degree, rendering them essentially useless and misleading.If you want me to clarify, I will. Otherwise, they, and reference to them, should be deleted to avoid their continued misuse by Faith (intentional or not).Thanks.(I'm not sure how well this is working with hands tied to the extent that I can't correct misreadings. Perhaps you two should just go at it and skip the invitees...)

1. The fact that mutation occurs is predictable.2. Mutation to produce a white mouse coat from a black-coated inbred population is NOT predictable beyond the scope of (1). That is, if mice with novel phenotypes show up regularly, it is a testament to the frequency of mutation, and in no way suggests a predictable bias for mutation towards those novel phenotypes.3. You are over-focusing on the coat color issue. Just because I used coat color as an example, does not mean that I was exclusively referring to mutations involved in coat color. Something is "built in" - it is called "mutation". Again, no. My post used an example of mutation of a coat color gene to explain generalities regarding mutation - there is no bias towards mutation of coat color genes. The only predictable thing is that mutation will occur at every generation. In the example I gave you mutation was demonstrated conclusively via genetic analysis to be the cause of the coat color difference. There is no room for discussion on that point - the mice had an allele that their grandparents did not have.The domestic mouse line was not selected for white coats (in fact it was selected for black), so you cannot try to explain the arisal of white coats as a product of artificial selection.
___________robinrohan: If you think this post is out-of-line, or I "stepped on your toes", I will delete it.

Unfair because of the subject matter? or unfair because it was unsolicited?If the latter - at some point Faith stated that I was invitee and of course I should participate - perhaps it was meant just for that one point, but I took it as a slightly more open to clarifying up-in-the-air issues. Like I said above, I'll now limit participation to when I am specifically asked.I also think it is a good decision to exclude randman from debate of embryology since his "Haeckeling" has derailed too many threads already. I would hope that randman would agree with me on this point.

Their great grandparents don't matter; to explain:(Excluding mutation) all of your genetic information comes from your parents. All of your parents' genetic information comes from their parents (your grandparents).Thus, essentially all of your genetic information originates from your grandparents' genetic information.If you have a version of a gene that your grandparents don't have, then that is a result of mutation, because the only other source of genetic information is your ancestors. (Of course the other options are that you or one of your parents were adopted, or one of your grandmothers or mother committed adultery).Here is an example of a hypothetical six-base "gene X". Humans have two copies of each autosomal gene; "alleles" is a term used to designate different forms of a gene. Gene X has three alleles, which I have color-coded based on sequence:grandma 1: ATGCTA & ATGGTA
grandpa 1: ATGCTA & TTGCTA
grandma 2: ATGGTA & TTGCTA
grandpa 2: ATGCTA & ATGGTA
you: TTGCTA & ATCCTABy looking at your alleles (copies of gene X), we can see that you have the TTGCTA allele that you inherited from either grandpa 1 or grandma 2; but you also have the ATCCTA allele, which you could not have inherited from any of your grandparents, because none of them have it. The ATCCTA allele is a result of a mutation. Even if one of your great-grandparents was carrying the ATCCTA allele, yours would still be the result of a mutation, since it was not passed down through your grandparents' genes. And thank you for being specific. I hope I haven't overexplained, but I wanted you to fully understand why analysis of the great-grandparents was not required to reach the conclusion that mutation occurred.

I'm learning from this thread, in part that I have to be really careful with my examples, since this is the second time a specific (and in the latter case hypothetical) example has been used to make a mass-generalization. You are correct, but this rarely happens. I was trying to get a separate point across - please try to be careful about generalizing small details in examples, and I'll try to be more careful in my wording of examples. The creationists needn't bother, since evolution geneticists are already doing so, and have already uncovered such non-random inheritance. From a recent publication in the journal Nature: I think if both you and robinrohan were less adversarial towards the opposite viewpoint you would both learn a lot more in this process.

Hey Faith, thanks again for my own emoticon. The language is so tricky when it comes to this topic, which is why many on the evo side simplify (or simply insist) mutation as random.I see mutation as "a built-in mechanism" because it seems that DNA polymerases (the enzymes that copy DNA) are evolutionary optimized to make a few mistakes each generation. I have some recollection that there was a study done where scientists were able to reduce the error rate of a DNA polymerase beyond the already low rate provided by evolution's version. The idea is that if a species lineage evolved a "perfect" polymerase that didn't produce any errors/mutations at each generation, the species is unable to adapt, and so dies off as a result of their evolutionary dead-end. (I would take this with a grain of salt until I manage to produce a reference for you).If this is the case, that polymerases have evolved to make a few mistakes, than mutations are "a built-in process".I see mutations as non-random - but others have argued with me that this view has to do with my definition of "randomness". Let me explain how I see it: There are various mutational biases that cause some stretches of DNA sequence to be more prone to mutation than others. On top of that, the type of mutation that will occur appears to be biased by the local DNA sequence. I see these biases as "non-random".However, there is no evidence that any type of sequence is mutation proof, or cannot experience a specific mutation. This means that all possible sequence changes are real possibilities for selection to act upon. In this sense I see mutation as "random", because it can change/produce any possible sequence combination.Also, when the mutational biases act to produce a pattern, it is towards simple repetitive sequence instead of the sort of sequence that genes are made of - so it doesn't appear that the biases represent a gene-producing program. This is another reference I could dig up for you at some point. We all have been nicely nonadversarial in the thread, except for a few moments from each of us (though like you say they could be miscommunication). I took your "Creationist should research this" comment as more smug than it was probably intended. This has definitely been my most enjoyable interaction with you thus far.Hopefully you don't take my language as too pro-evo biased; if I state that something evolved as a fact (like I just did above), it is not because I am taking robinrohan's side in the argument, it is more because I am trying to state mainstream science's current understanding. I'm doing my best to stay neutral.I've got to sign off now for several days for the holiday weekend, and I think it may be best for me to take a break from this thread for a bit anyway to avoid it becoming too much of a Faith & Pink mediocre debate - I don't want to take anything away from robinrohan. If you are interested in those references I mentioned and I don't post them, please feel free to give me a reminder when I show up again in a week or so.Have a happy Festivus! (and/or any other holiday you wish to celebrate!)