Here I go again...
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Originally Posted by CSflim
What is a natural event? Ants engage in war. Is this unnatural too? Or only unnatural when humans do it? Why the distinction?
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Allow me to explain a little better. War is natural. War on the scale that we have it is definitely not. A plane flying over and dropping a nuclear bomb (or hundreds of other bombs) is not natural. Although the idea of warfare is seen (albeit rarely) in other forms of life, we wage warfare using products of technology which are not natural, and makes our wars unnatural. Also, other animals do not consciously commit genocide (the best known way of cutting down on aspects of the genepool).
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Originally Posted by flstf
I don't understand. If people who would ordinarily die from disease before they are able to reproduce are now kept alive to reproduce won't they pass their weaker immune systems etc..on to the next generation? As an example if we save the half million children listed below with early medical treatment won't they pass on their weaker genes?
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Yes, they will pass on their genes. This is why the genepool is staying the same. If they died and did not have children, the genepool would change (theirs would no longer be in it). But since their genes are in it now, if they have children the children carry their genes also, and the genepool does not change.
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Originally Posted by zen_tom
I'm interested in the idea that selection (of a mate) is more important than fitness (for reproductive survival) Something I read about Peacocks made me think about it.
A Peacock has a huge, beautiful tail that seriously hinders its movements, making it an easy catch for predators - however, because the Peahens like Peacocks with big tails, their chicks who will grow up to have big tails (and the preference for big tails) This feedback loop of genetics creates, in the case of the peacock, an extreme body shape - similar things occur in other fowl, insects etc, but often the most extreme body forms relate in part to quality/preference pairings.
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It's not that the tail is more important than fitness... It's an INDICATION of fitness. A tail costs a lot of energy to grow, slows the bird down. Therefore it takes a very fast, strong peacock to outrun predators even with the large tail, and it also means the bird is well fed since it had that extra energy. Therefore it actually helps the peahens select the most fit peacocks.
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Originally Posted by zen_tom
. . . this quality/preference thing to me seems like it could be a much more powerful influence (especially in reasonably 'comfortable' environments)
If that's the case, it could explain the rapid evolution of our species, and mean that without genetics etc we may still be in a period of rapid development.
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Although this is a matter of opinion as much as anything else, I would say no. The reason for that is even under many selection pressures, we still cannot evolve faster than our genes can mutate. This being the case, and with the generation time ever increasing, natural evolution is a slow thing for humans.
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Originally Posted by CSflim
You make a correct point, that 'fitness' is measured not only by the ability to sucessfully reproduce, but also based on how many times reproducution occurs. But it remains to be shown that women (or men for that matter) with socially desirable qualities reproduce more often than others. It is likely that they have sex more often, and with more partners, but with the widespread use of contraception, maybe this point is rendered insignificant?
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I like the point you're making how the amount of sex doesn't correlate to the amount of offspring. Also, the alleles (traits) are not evenly distributed. Someone with a great personality might have small breasts, but you don't care because she has a great personality... Or a very attractive male could be dumb as nuts... Because the alleles are so spread out in the population, it's very hard for sexual preference to translate into sexual selection. Reproduction is, in this sense at least, somewhat random.
Oh, and the reason large breasts used to be a sexual preference is also because it is a sign of fitness. Those large fat deposits mean the female is well fed and therefore more likely to be fit.