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Originally Posted by CSflim
This is a point of contention and is not accepted across the board by all biologists.
I am not an evolutionary biologist, so am not really qualified to comment on it, but I must say that I find it a bit far-fetched. I find 'memetic' explainations of sexual selection very useful.
Regardless, just to ensure people don't consider tentative hypotheses as on the same ground as established science.
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True, it is a hypothesis, but how are you going to prove it? The only thing provable is that females like the males with big tails. You can't ask the peahen what it thinks. Fact is, it does take a lot of energy to grow and only strong, fast peacocks can avoid predation because of it. From the standpoint of selection pressures, there would be no such pressure for a female to evolve to desire a mate with a feature that merely acts as a hinderance (which is what it is doing if she just wants the tail because it's pretty). The only way that this could be taken as an indication of fitness is because the bird wants it to be. On the other hand, it being an indication of fitness makes it easy to see what male has the best traits. I'm not saying that one is definitively correct, but I think theres an answer that definitely makes more sense.
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Originally Posted by CSflim
Evolution happens at a faster rate when the selection pressure is high. Although the mutation rate is, in principle, a limiting factor, in almost all cases it is the selection pressure that determines the speed.
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Where are you getting this idea from? If mutations occurred faster than the selection pressure could be applied, then there would be no extinction from predation. This is like saying organisms are able to adapt faster than they could be killed from a natural cause, and it simply is not true. If it was, why aren't all animals on the African plains that are hunted by cheetahs able to outrun the cheetah? And if they became too fast for the cheetah, why would it then not become even more fast to avoid the starvation of its species? The situation of the limiting rate being selection pressure would put evolution proceeding at a rediculous rate; one that the mutation rate would have no chance of keeping up with.
Mutations occur very, very seldomly (in the sense of mutations / base pair replicated) and are completely random. The genes don't get up and say "we have a pressure, here... we need to do this". It's all just chance, and some chance works out better than others, and chance takes a long time until you reach something meaningful... Similar to the saying about an unimaginable amount of monkeys with typewriters would eventually create a work of Shakespeare.