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

Number 6 is another way a mutation can occur. It's a gene that moves around on a chromosome. #7 is a preference for one particular type of a mate. The example given is of a certain female fish that prefers a mate that feeds in a certain place (rather like a woman who prefers men who take her to fancy restaurants). These particular males have some markings on them for some reason. The author says this can lead to speciation. I think I got the point. I'm just not sure I agree with it.I'll study up some more.

Sorry, I meant 2, 5 and 6 rather than 6 and 7. Sexual preference is a population category. I don't know what movable elements is, {AbE: goofed again, not moveable elements but variable whatever it was} but it's something to do with genetics as such rather than populations. OKThis message has been edited by Faith, 12-20-2005 11:29 PM

OK, I've read some of what you said on the other thread, and I think your point is that significant evolution cannot occur without mutation.I think I agree with that.But what about this scenario: (I copied this from a post I wrote earlier, elsewhere.)There's a group of little black furry creatures living in the forest called Eutherians. One day, one of these is born with some brown specks on his coat. This was due to a purely random mutation. By sheer chance, these brown specks are an aid to camouflaging in the bushes. The bushes are brownish too. There are some big bad predators stomping around, but the one with specks manages to hide, and it reproduces. Some of the others also make it through to adulthood. The speckled Eutherian gives birth to a litter of six, and five of these are speckled like its parent. All these live and breed but the unspeckled one is eaten by predators before it can reproduce.If you go through enough generations, all of the Eutherians will be speckled whereas before they were all black. This mutation was beneficial. Other mutations are neutral. Still other mutations are detrimental. The ones that are detrimental don't last through many generations. Whether the neutral mutations last is purely a matter of genetic chance. Natural selection will filter out all the ones that are detrimental.If one of the Eutherians was born white, for example, and white allowed the predators to spot him easily, he would not last long enough to reproduce.Would you agree that this type of scenario can and has happened?This message has been edited by robinrohan, 12-21-2005 02:10 AMThis message has been edited by robinrohan, 12-21-2005 02:11 AM

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OK, I've read some of what you said on the other thread, and I think your point is that significant evolution cannot occur without mutation.

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I think I agree with that.

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But what about this scenario: (I copied this from a post I wrote earlier, elsewhere.)

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There's a group of little black furry creatures living in the forest called Eutherians. One day, one of these is born with some brown specks on his coat. This was due to a purely random mutation. By sheer chance, these brown specks are an aid to camouflaging in the bushes. The bushes are brownish too. There are some big bad predators stomping around, but the one with specks manages to hide, and it reproduces. Some of the others also make it through to adulthood. The speckled Eutherian gives birth to a litter of six, and five of these are speckled like its parent. All these live and breed but the unspeckled one is eaten by predators before it can reproduce.

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If you go through enough generations, all of the Eutherians will be speckled whereas before they were all black. This mutation was beneficial. Other mutations are neutral. Still other mutations are detrimental. The ones that are detrimental don't last through many generations. Whether the neutral mutations last is purely a matter of genetic chance. Natural selection will filter out all the ones that are detrimental.

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If one of the Eutherians was born white, for example, and white allowed the predators to spot him easily, he would not last long enough to reproduce.

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Would you agree that this type of scenario can and has happened?

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It's a typical natural selection scenario, completely commonplace. What point are you trying to make? The only question I have about this sort of thing is the part about how a mutation set it in motion, the sentence I bolded and italicized. I don't think a mutation is required, in the sense of a completely random alteration in a gene. I think it's a built-in possibility that just happened to get expressed. There are sometimes many genes for one trait such as fur patterns and colors as I understand it, requiring no mutation but simply genetic shuffling business-as-usual to turn up something like your brown specks.This is where I need to try to get a better understanding of these genetic processes, but my impression is that it's all in flux at the moment anyway, the whole DNA replication thing still being quite new and all that, so I think the better understanding is a few years into the future, whatever my own abilities amount to.This message has been edited by Faith, 12-21-2005 08:27 AM

Actually, I also was not sure. I'm making the point that this is how evolution works, if you leave out all the other complications. This is the basic idea--natural selection plus mutation.But if it can change the coat color, it can do other things as well.Any mutation, if beneficial, has a good chance to be incorporated as a trait for a group. Given enough time, macroevolution can occur.But I want to know at what level your idea of Kind is--you said it was not the species level. Perhaps the family level? I think butterflies as a whole, for example, are on the level of family.

Anything that selects alleles out of a starting pool of alleles, leaving some behind, changing the frequencies at least, or eliminating some altogether, and isolates the new selection so that they interbreed for a number of generations, produces the changes known as "microevolution" -- Natural Selection is only one process that does that. As for mutation, it has yet to be shown that iit adds beneficial changes at any rate that challenges the diversity-reducing effects of the various selecting processes. But is it really mutation? The probability of beneficial random mutations is pretty low.The first thing to recognize is that mutations are not necessary for the natural selection scenario to work. All you need is many genes for a trait and a couple of recessives getting expressed that happen to have a protective function of some sort in the current environment. They will get selected just as this hypothetical beneficial mutation would. Plain old Mendelian genetics. If blue eyes were necessary to survival in a certain environment, all the big brown B's would die off and leave only double-bb's. There's no way to know. I think it will have to be defined genetically rather than taxonomically. But yes I would guess a Kind would be frequently at the Family level, but some maybe higher, some maybe lower.This message has been edited by Faith, 12-21-2005 09:36 AM

I'm not so sure there's as much diversity-reducing effects as you claim. A lot of time, a population just maintains the status quo, as perhaps in migration. What difference does it make how many there are? If the group is successful, you are going to have a lot fairly soon and the recombination possibilites are going to be like before the group split.But for significiant evolution to occur, there has to be new traits via mutation. If the speckles on the Eutherian was due to a recessive gene being expressed, then somehow that gene had to get in the mix in the past. Here, perhaps, is the crux of your objection to TOE? That's why evolution takes so long. For long periods of times--many millions of years in some cases--there will be no evolution for many life forms. Once a species gets to a point that it survives well, once it reaches what my book calls the "optimal genotype," there's nothing to make it evolve anymore--like your friend the lungfish.But if there are changes in the environment, then the bets go up for beneficial mutations. There have been various and extreme changes in the climate of the earth through the years. This is one of the spurs of macroevolution.ABE: changed "the spur" to "one of the spurs."This message has been edited by robinrohan, 12-21-2005 09:04 AM

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.

To judge from presentations on basic population genetics, the diversity-reducing effects are the majority of the processes that produce the changes that are called microevolution. Death is inexorable in nature and alleles die all the time, so over time these processes are the trend, cumulative over time, counter-evolution though it is. Yes on the way down some populations will establish relative equilibrium (it can't be perfect because of random genetic drift), and recombination does happen sometimes, reintroducing diversity for the time being, but as I said that adds BACK alleles, it doesn't add anything new genetically speaking though it could certainly save a population from severe genetic depletion or extinction for the time being. But only mutation supposedly adds anything new genetically speaking. If mutation happens at all as they claim it does. Not necessarily. New traits can be the result of inbuilt genetic potentials, quite predictable chemical changes along the stretches of DNA known as genes. Sure, it was part of the original complement at Creation. What about the supposedly very high rate of mutation that everybody talks about here? Given that, how does any species remain in stasis for any time at all? And why is that? That sounds positively Lamarckian.{AbE: OK, you're talking about selection pressure, environmental changes that actually kill.}This message has been edited by Faith, 12-21-2005 10:28 AM

In other words, I was right.

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We are here as on a darkling plain
Swept with confused alarms of struggle and flight,
Where ignorant armies clash by night.--Matthew Arnold"It's a tale told by an idiot, full of sound and fury, signifying nothing."Our Nada, who art in Nada, Nada be thy name. Hail, Nothing, full of Nothing, Nothing is with thee.--Hemingway

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

How can it be considered a random process if it's so predictable?

I don't know what the rate of mutation is, but a species can remain in stasis despite mutations because they are at their optimal genotype, and so the mutation has no effect on their ability to survive and reproduce. So it's a neutral rather than beneficial mutation. If it survived it would be by chance. The creature doesn't need to change, so it doesn't.Even a trait that one would think would be an obvious advantage might not be in a given situation.Let's take my example. The Eutherians became over time speckled and were able to survive the predators and give birth just fine, thank you. One day there was a mutation and a puppy was born with a better sense of smell. You would think that would be an advantage, but in this case it is not. They don't need to smell better to survive. So the trait never takes hold. Yes, and it wouldn't have to be just a climate change. Perhaps there was an invasion of a new type of predator. A trait might emerge that helps survival against this new type.

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.

Faith, I was under the impression that invitees are only supposed to comment about what we ask them. However you want to do it is fine with me.