Failed mutations

I was having a discussion with my wife the other day and she asked me a very good question that I had never thought of. 2 of the main pillars of theory of evolution are random mutations and natural selection. Random mutations that give survival advantage to a species are sustained and are passed on to the subsequent generations. We now have found intermediate fossils in many species including homonoids.My question is have we found any fossils with mutations that did not confer survival advantage to a species i.e. fossils with mutations that were useless to the species. For every mutation that gave selection advantage to a species there must be millions that did not. Am I right? So, we should be able to find more such fossils.

Thread moved here from the Proposed New Topics forum.

First, it is the survival of the individual that is selected.Second, all fossils are dead - ie they have not survived until today.Third, a single mutation does not necessarily have much effect on the phenotype of the individual: do the color of your eyes matter to your survival?Fourth: severely deleterious mutations would most likely cause death of the fetus or the newborn.Fifth: we can't always tell the cause of death from a fossil.Enjoy.

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I don't mean to nitpick, but I don't like the way this sentence is written out.Evolution isn't about a creature setting a goal to become another and then half way there we can find an "intermediate" somewhere along the line. Technically speaking, every creature that have ever existed is an "intermediate".Evolution is an ongoing process. There is no such thing as a specific form the creature has to be. Every creature is an intermediate between its parents and the next generation.That said, if you set out to find a fossil with a head of a croc and a body of a duck, you're not going to find any. That's not evolution. That's creationism. If the mutation brings a disadvantage to the species as a whole, it would be deleted via natural selection pretty quickly.But to answer your question directly, all you have to do is look at every fossil of every dinosaur that we've ever found. Obviously, something went wrong for them all to have gone extinct. Good enough example?

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I'm trying to see things your way, but I can't put my head that far up my ass.

See what your wife has to say about this. I'm not sure if it quite counts, but it seems logical to assume that this was a failed mutant (based on the evidence of lizards and snakes with similar mutations/aberrations). I'm also not sure it's due to a mutation, per se: it could be a freak hormone problem or the mother was on crack or something.

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In the broadest sense you could consider any evolutionary lineage that became extinct to have been the possessor of 'failed' mutations, but it really makes no sense since as TAZ points out there is no intentionality or purpose to mutations so to talk of them as 'failed' is confusing.The best we can do is talk of them as deleterious. By far the best evidence of the presence of deleterious mutations in previous generations is not something like the fossil record but the evidence of deleterious traits that have nevertheless become fixed.As far as possible examples in the fossil record I might suggest looking at some of the weird fauna of the Cambrian, they have many phenotypic features which are not extant in any current species we know of. Alternatively what about species such as the terrorbirds and other macrofauna which are no longer with us, or even the mammoths?On a mutation by mutation basis there is absolutely no way to do this sort of thing from the fossil record, unless you found a fossilised embryo failing to gastrulate or a fossil animal with a cleft palate, but the first of these is lethal and the second need not affect fitness dependent on its severity. It should be obvious from the fact that looking at any normal population the majority of people don't have visible phenotypic defects that similarly the fossil record is going to have a much higher proportion of phenotypically 'normal' specimens. If you think about the relatively low prevalence of visible effects of genetic mutations in an extant population why would you expect them to be overrepresented in the fossil record? Most of the millions of non-advantageous mutations would simply be neutral, as with most mutations today.TTFN,WK

This is the wrong question to ask, in a couple of ways.First, we can't tell anything about mutations from the fossil record. All we have from fossils is their bones and sometimes some impressions of soft parts, sometimes even soft tissues, but very rarely any DNA, and certainly not in sufficient quantities and degree of preservation across ancestral and descendant species to figure out mutations, let alone figuring out the mutation's effect on the species.So the question has to be reformulated as, "Have we found any species in the fossil record with a characteristic (or characteristics) that did not confer a survival advantage?"And this brings us to the second reason why you're asking the wrong question. Whether a particular characteristic is advantageous, disadvantageous or neutral to survival is a function of the environment, which includes weather, geography, and all the surrounding flora and fauna. In most cases it would be very difficult if not impossible to conclude that any particular characteristic was disadvantageous for a particular environment.But environments inevitably change, and species must either adapt to change or go extinct. That more than 99% of all species that have ever existed are extinct tells us that sooner or later the environmental changes become large enough, or the rate of environmental change becomes fast enough, that the species cannot adapt through the evolutionary processes of mutation and natural selection and so goes extinct.In other words, fossils of all extinct species must by definition possess a combination of characteristics that were disadvantageous for survival in their environment as it existed when they became extinct (there are exceptions to this, of course, e.g., species too close to ground zero when an asteroid struck). If this weren't true, these species would still be with us. Yes, this is true, but the vast majority of mutations provide tiny, unnoticeable change. (There *are* types of mutations that can cause broadly noticeable change, Downs Syndrome is a well known example, but these types of mutations are not thought to be a significant contributor to evolutionary species change.) The accumulation of many tiny changes over long periods of time is required before any noticeable differences would be detectable from examination of fossils. It might help to realize that based upon skeletons alone, lions and tigers are indistinguishable. This tells us that the number of mutations necessary to produce noticeable skeletal differences is enormous.--Percy

Yes, failed mutations are the causes of disease in humans.We all carry about 6 mutant genes that are harmful in
homozygous form.

I know what you're getting at with the misunderstanding of the "head of a croc and a body of a duck" type intermediates, but in the same way as you said: I don't mean to nitpick, but I don't like the way this sentence is written out.Species can enter a stasis and go relatively unchanged for long periods of time. Then, when some selective pressure initiates, the species will change and then maybe go into stasis again. The way you wrote it makes it seem like stasis never happens. The individuals during the changes between stases, could be considered as more "intermediate" than the ones in the stasis. You know what I mean? What went wrong with the dinosaurs wasn't a result of mutations, though. A big meteor came down and killed them...I guess you could say that whatever mutation they had "did not confer survival advantage", but he seems to be looking for useless mutations (or 'bad' mutations).Maybe a better example is the Dodo bird. Its 'mutation' was that it wasn't really afraid enough. This got it killed off by man.Or another useless mutation would be eye color, or anything else that is neutral to survival.The dinosaurs seem like a bad example to me.

See, we don't know this. Sure, there are many examples of species having the same physical form for many millions of years without a hint of change. The sea turtle is an example. But notice that on a chemical level there just is no way to tell. The chemistry of the sea turtle 10 million years ago might be so different than the sea turtle today that if you could bring one forward 10 million years it would not be able to breed with one today.One thing we do know is that because mutation is inevitable the change in allele frequency is inevitable. Yes, I know what you mean. But even these species who are in so-called long term stasis are not actually in real stasis. As I said earlier, there might be large changes in their chemistry from time to time that the fossil record simply couldn't record. Huh? The mutations that ultimately resulted in the dinos didn't include genes that would allow them to survive a big asteroid smashing into Earth. On the other hand, small mammals and ancient reptiles like the croc survived. So, clearly, the dinos had bad genes to deal with the selective pressure. Yes, and I also answered this in my previous post. There's a reason we call deleterious mutations deleterious mutations. They get deleted rather quickly if there's sufficient selective pressure against them. His question basically amounts to something like "how come we don't have any live example of living people that are tetraploids?" Um, because they'd die before they could even become a zygote? From what I interpret the OP to say, I don't think he meant useless mutations. I think he was referring to deleterious mutations. Haha, yo mama.Added by edit.Ok, I reread the OP. Yes, he seems to be referring to useless mutations. My answer to this is this.If you think about it, the fossil record is a snapshot in time of the physical traits of certain creature. In other words, it can't possibly record subtle traits like eye color. The thing is if a "useless mutation" that is large or noticable enough to be recorded by the fossil record would be in itself a deleterious mutation. It requres energy to carry around extra body parts that don't do anything. Imagine yourself carrying around a 50 pound piece of meat on your behind. I'd say something like that would slow you down enough for you not to be able to compete for food in the wild. I regularly have to run around to hunt for creationists to put food on my family. I can't imagine myself being able to do that with an extra useless body part hanging off my rear end.So, anyway you look at it, any useless trait resulting from mutation that is noticable enough for the fossil record to record is in itself a deleterious trait that would not survive for long.Edited by Taz, : No reason given.Edited by Taz, : No reason given.

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I'm trying to see things your way, but I can't put my head that far up my ass.

I'm not entirely sure we can use the fossil record to come to any conclusions about anything.Many creatures are not "transitionary" in that they become extinct without any members evolving and carrying on.Since there's no real way to tell whether or not that particular fossil is transitionary "except for visual guesswork" no fossil can be used in a serious study of evolution. Having said that, there should be pleanty of evidence in live creatures of mutations.RAZD once mentioned that some dogs have less paws. Any study about that mutiation should be more valid than looking at bones of who knows what or when.Edited by Marcosll, : No reason given.

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Yes there is ... ... but that isn't it. Deleterious doesn't mean that the genes get deleted, it means that the mutation is harmful to the organism. We would expect such genes to be selected against, but that tendency towards removal from the gene pool is not why they are termed deleterious.TTFN,WK

Sure we can. Just go to any dinosaur exhibit.You should be careful in using absolute terms like any conclusion about anything, because someone only needs to come up with one conclusion about something to make your statement false. For example, by looking at a fossil skull of a dinosaur, we can conclude how many eyes it had This statement seems to expose a gross misunderstanding on your part. Members, as in indiviuals, do not evolve. Only populations evolve. I disagree. Take a look at this image: Now, we know that whales have hip bones. If we can see this string of fossils with gradually shriking legs and changing hips, then we can see that whales evolved from land dwelling creatures. (of course, there's more to it than just that) You seem to be trying to discredit anthropologist's abilities to draw information form fossils....tsk tsk

I stand corrected.But the main point stands.

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I'm trying to see things your way, but I can't put my head that far up my ass.

My point still stands.The chart: http://members.aol.com/darwinpage/whale1.gifStill only shows similarities between fossils from different times. One could take bones of modern creatures and construct a similar chart.I also have a serious problem with the time scale on that chart. At current observed rates of change it doesn't seem like nearly enough time .