Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution

It sounds like you had a different take on the show than I did. No big deal.--Percy

Then what is the point you are trying to make?

The runaway sexual selection gene is shared by both sexes. You have, but I don't think that is a valid opinion. It's like saying that evolution doesn't apply to humans. So I am questioning it because I think you use that argument to avoid the comparison of animal runaway sexual selection to human runaway selection.Enjoy.Edited by RAZD, : ..

That runaway sexual selection has been a factor in human development for a very long time, that it is how we came to be "the hairless ape" in the first place, that it is how we cam to be sexually active on a monthly basis rather than a yearly basis, that this is how we came to have females with year-round full breasts and men came to have much larger penises than all other apes ... that sex is what made us distinctively human. It may well be what set hominids apart from chimps.What we see today is just more of same with new technology being used.Enjoy.

It's possible to agree with much of this and still not reach all of the conclusions you do. One might also point out that bonobos are certainly sexual apes so perhaps the distinction is not as clean as you suggest.

What the heck does that mean RAZD? In what sense is my opinion invalid? You can question it all you want. But I am not saying that evolution does not apply to humans. Not even close. I am saying instead that humans can develop behavior patterns in ways other than developing instincts and are more likely to do so than most other animals. In fact, humans are able to develop such behaviors in far shorter than evolutionary times. Humans have no need for 'want my breasts enhanced' gene because they have plenty of societal cues that tell them that men like big boobs. And I'm not avoiding the comparison with animals. I'm simply not persuaded by it, primarily because of the different roles instinct plays in humans. And not every disagreement with your opinion is based on some kind of mental malfunction. Perhaps a better strategy for convincing me would be to show me the deficiencies in my position rather than impugning my motives.Edited by NoNukes, : No reason given.

That's a very strong argument. I think it will require more evidence than 'dudes like tits' and 'chicks like dicks'.There have been individual threads on each of these points, and in every case it was clear that there is ambiguous evidence and enough evidence to argue for either position (or both).I think sexual selection probably plays a pretty big role. But I don't think it plays the only role, and I would never go so far as to claim it solely led to the hominid line and eventually us. I think that overlooks the existence of obvious non-sexual benefits to our upright walking, our big brains, our use of language, etc.So I'll say it again: you simply haven't provided the nail-in-the-coffin evidence required to support your conclusions to the level of certainty that you preach them.

I don't think any of the respondents in this thread are going to dispute that sexual selection has an important functional role in evolution. The question you seem to lack an answer to is why we should think it was so uniquely important in shaping these human traits and why we should think that your answer of sexual selection is more compelling than the alternative hypotheses.Popping out weaksauce support for your position like the modern fad for hairlessness in porn isn't helping your case.

Yet there is no evidence of run-away sexual selection, most likely because they don't appear to 'compete' over sex but share it. The female and male sexual development is virtually the same as the chimpanzee. Penis size is small, breasts only fill when lactating, facial characteristics are not childlike in adults.Enjoy

But it's not just sexual selection -- it's runaway sexual selection. That is what drives selected traits in a direction that comes up against the limits of variation in the population, traits that are exaggerated in the individuals compared to other species, especially close cousins like the chimpanzees and bonobos.We look at text-book examples of runaway sexual selection -- peacocks and scissor-tail flycatchers -- and we see selected traits driven in a direction that comes up against the limits of variation in the population, traits that are exaggerated in the individuals compared to other species, and recognize it for what it is: fisherian run-away sexual selection.As stated in Message 1:

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The identifying characteristics of run-away sexual selection, then, that differentiate it from normal sexual selection, involve a feature (or features) carried to an extreme that is not needed for species survival (and which may even jeopardize survival), and that may still be selected for if it were possible to undergo further (still continuing?) evolution.

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This would be evident in a skewing of the population chosen for mates versus the variation within the population (demonstrating that it is one extreme end of available variations that is consistently chosen), and it would also be evident in comparison to closely related cousins without the features (demonstrating that the features are not needed for survival): all the longer tailed male birds mated, and close cousins do not have a long tail.

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That doesn't make us "special" when we see similar extreme trait selection and development, it just explains how we got to where we are with those traits.If you have a better explanation then trot it out and let's see how it compares.Enjoy.Edited by RAZD, : msg1 ref

The problem, RAZD, is that you're not trying to explain one human trait in such a way but that you're trying to argue that multiple human traits are the result of separate runaway sexual selection. That's a pretty extraordinary claim and argues for special status for human selection.And even for each individual trait you have no strong evidence that it is the case:You also have chosen traits which don't conform to the classic model of runaway selection - hairlessness is not a disadvantage, for example, whilst intelligence has multiple straight forward selection benefits. Traits which don't conform to the dimorphic pattern of runaway sexual selection - men are not smarter than women, women are not markedly different in musical talent, men and women have similar natural head hair (until older ages, anyway), only in body hair is there dimorphism and even there it is slight. And traits for which attractiveness to the opposite sex does not show the marked and consistent needed to explain the differences you want to explain by sexual selection. And, finally, human mating patterns are not well suited to runaway sexual selection since we pair-bond and have done throughout Homo's evolutionary history. No, I'm not getting into that game. You've made the strong claim that multiple, important, human traits can be attributed to runaway sexual selection. You need to present credible evidence that this occurred.