Natural Limitation to Evolutionary Processes (2/14/05)

First of all, that's not a bad habit at all. The best ideas come from people thinking outside boxes. The important trick is to remember to check the box occasionally to see if you're still thinking outside the same one. When you're talking about evolution there's no getting away from reproductive fitness because that's what evolution is all about. But let's concede your point for a moment.A first reaction to that could be to say that something that escapes selection and does not interfere with reproduction, does not work against evolution, nor for it, because evolution is nothing but reproduction with selection. So something that affects neither, must be neutral with regard to evolution.But on second thought one could say that it might have some influence after all, when, for instance, the elder, non-reproductive members of the species are a factor in the survival of the young ones until they reproduce. In other words, if the grandparents are looking after their grandchildren while daddy is out gathering stuff and mummy is out hunting (let's say we're talking about a very modern population), then it might be a bad thing if they are too weak for the job, for whatever reason.However, unfortunately for your argument, this does not mean that it works against evolution. It may work against the survival of the species, but no one ever claimed that evolution is about the betterment or the preservation of species. Evolution is simply the process of change in living nature. If this change entails the extinction of a species, then so be it. It's simply the way things go.

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.

You want truly beneficial mutations? How about the mutations that:

• caused a cell to become sensitive to light;
• caused a patch of light sensitive cells to become slightly concave;
• caused a primate's thumb to become slightly more opposable;
• caused an insect to become slightly better camouflaged;
• caused an insect-eater to become slightly better at detecting camouflaged insects;
• caused the plumage of a bird to become slightly more attractive to a potential mate;
• caused a flower to become slightly more attractive to certain pollinators;
• caused the leaves of a plant to become slightly less palatable to herbivores.

I could go on and on. And I can assure you that the list is comparable in length with the list of truly harmful mutations. If mutations are random, then it is to be expected that there are about as many beneficial mutations as there are harmful ones. To keep things simple you can say that natural selection makes sure that the beneficial ones are kept and the harmful ones are weeded out. (In reality, a lot of beneficial mutations are lost as well, because of accidents, disasters, et cetera.) This is not an intentional process, it's just what must happen, logically. The diversity we see around us in living nature and in the fossil record is in fact a log of a massive amount of beneficial mutations that have happened throughout the history of life on earth.

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.

You're right, I stand corrected. I did not make any such calculation, and it was indeed guesswork. I have no idea what the distribution really is. But that does not detract from the logical conclusion that the diversity in nature is the result of the selection of an enormous row of beneficial mutations^*.Faith's complaint is that there are so many harmful mutations and that no one ever provides examples of beneficial ones. All I wanted to point out is that the list of beneficial mutations is right there, for everyone to see, in the "log of nature", so to speak.But thank you for pointing out my error. It should serve both as an example of how the scientific process works (not that I want to pretend that my ramblings have any scientific value whatsoever, but I mean peer review and all that) and as a reminder to myself to do some more research before posting.___ *) While proofreading the above before posting, I realize I should add that the "log of nature" is as much the result of the weeding out of truly harmful mutations in favour of perhaps not really beneficial mutations, but rather mediocre, just-good-enough mutations. In that respect Faith may be right, and there may not be so many beneficial mutations. But good enough is what it is: good enough.

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.

Let me lure you into a trap. I'll tell you up front it's a trap, that much seems fair.Since we're not allowed to reason backward from the assumption that the theory of evolution is true and may therefore not explain nature's diversity as the result of the theory's mechanism, implying unobserved beneficial mutations, which is fair enough, how about turning this thing around then? Let's look at some observed beneficial mutations. There are none? On the contrary, there are a multitude of them. Take for instance the greyhound: I think we can assume that the greyhound did not exist 50.000 years ago. (I'm taking a very safe margin here.) That long ago, there were only the ancestors of all our modern breeds of dogs. (Whether these were wolves or coyotes is inconsequential for my argument.)These ancestors did not have the "long, powerful legs, deep chests and aerodynamic build" the Wikipedia article mentions. These properties must therefore be the result of many mutations in the long line of descent between the ancient ur-dog and our modern greyhounds. From the viewpoint of the greyhound, these mutations are definitely beneficial, for without them the greyhound would not exist.And what's more, these beneficial mutations have been observed. Keenly observed, I might say, because greyhounds are pets, human breeders have watched the race come into existence.So there we have it: observed beneficial mutations. No assumption the theory of evolution is true, just an example of something thousands, maybe millions of people have collectively witnessed over time.Now tell me where I've gone wrong.

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.

Faith,If you could find the time, could you please reply to two things before this thread runs out?First, your thoughts on the gene CCR5 giving immunity to HIV would be interesting. You'll find it mentioned here.Second, what did you think of my trap? (Here)

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.

Thank you Faith.I don't know if I'll be able to respond before this thread is chopped. I hope there'll be a continuation of it, in case it is. I have to think about an answer, and I have to go now.Sorry about the thing with you and Schraf. Why can't you both just address the argument? Why must the fur always fly when you two meet? It's really a pity, because I think the pair of you are two of the more intelligent people on this forum. I usually enjoy reading posts of both of you.

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.