03 Jun 2009

Just-So Darwinism

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[UPDATE below.]

I am not claiming in this brief post that “evolution is bunk” or that the Genesis account is the literal history of the six days of creation. What I am saying is that you will never find such open-ended, anything-goes theorizing in any scientific field other than evolutionary biology.

Consider this article (HT2LRC) on why we bald men are actually very attractive to young women:

Although many scholars have tried to identify a useful function for human hairlessness, they have failed. Indeed Alfred Wallace, the biologist who jointly described evolution with Darwin, concluded that our hairlessness proved the existence of God. Only a supernatural being, unconcerned with natural selection, could have designed it.

But Darwin showed that hairlessness was proof of a different type of evolution, not by natural selection but by sexual selection. Under natural selection, individuals survive if they are adapted to their environments: a brown bear, being conspicuous, would not last long in the Arctic, so it evolves into a polar bear. Sexual selection is not concerned with the environment but with sex: individuals breed only if they find a mate, so animals have to attract one. Consider the peacock.

OK so already we’re in trouble. The guy is going to use the example of a peacock’s plumage to prove why we lost our hair. (!!)

If that were the end of the story, I might say some wise aleck remark like, “If the guy were trying to explain why women had such lush manes, compared to the meager covering of the males, then it might make sense to bring up the peacock.” But I can’t go that route, because the “scientific Darwinian” story gets even more convoluted:

We human beings, too, are highly selected sexually, but in our case it is women who are the peacocks: the more beautiful they are, the greater the number and quality of the men who court them. This is why, some 75,000 years ago, we made our last two evolutionary advances: we lost our body hair and we invented art….

Art and hairlessness co-evolved because they fed off each other. The girl whose skin was least hairy could paint it, tattoo it, decorate it and clothe it more adventurously than could her furry sisters. So she got more and better men. And in consequence her children – even the males, though to a lesser degree – lost their hair too. We had become the naked ape.

OK, you got that? Remember, the whole point of this story is to explain why older men with thinning hair are actually attractive to young women (despite the myths that Rogaine and others would have you believe, and despite all those male models with full heads of hair). So to do that, the story starts out with why evolution made women lose their (body) hair, which then caused their male offspring to lose their (body and scalp?) hair, even though the original motivation (sexual selection a la the peacock) never caused female baldness to become prevalent.

To repeat, I am not saying the above story is impossible. What I am saying is that the exact opposite outcome–namely, a trend of female baldness and men with much thicker hair–would have been a far more natural fit to the proferred Darwinian mechanism.

You see this all the time in pop evolutionary biological accounts, where a plausible Darwinian story is deployed when it just as easily (indeed, often more easily) could have been deployed to fit the reverse set of facts. And a lot of the people who lap this stuff up, would be the first to denounce the non-falsifiability of unscientific Intelligent Design stories.

Sexual selection is the ultimate Get Out of Jail Free card for Darwinian theories. “What, that feature makes absolutely no sense and could only hurt the survival fitness of a creature? Well, the females must be turned on by vulnerability. You’ve seen Beaches right?”

UPDATE: OK I went back and re-read the article, and it seems that maybe the guy just took 85% of his space to discuss something completely irrelevant to male pattern baldness. In other words, he might have been offering the above story just to motivate the connection between human hair and sexual selection. When it comes to male pattern baldness, here is the scientific hypothesis:

Men have evolved to attract women. Because only some men go bald, we must assume that different women are attracted differently. Some women will be attracted to young men, but young men are untried and therefore risky, so some women will seek sugar daddies instead. Mating with sugar daddies invokes a different set of risks but the trophy wife is nonetheless making a rational choice – one that may well have been rewarded preferentially in the Stone Age – to which she is in part guided by baldness in her man.

Ah OK, we “explain” male pattern baldness as a response to sexual selection pressures. So why haven’t all men gone bald? Ah, we “must assume that different women are attracted differently.” Apparently conditions in one part of the African savannah favored sugar daddies, but in another part there were trees that yielded giant coconuts to the guys with full heads of hair and who knew how to dance really well.

I’m so glad we have abandoned faith and superstition, and now embrace Reason and Science.

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