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Darwin’s Other Dangerous Idea

Posted by Richard Conniff on February 24, 2013

Today in 1871, Charles Darwin published his Descent of Man. It contained his theory of sexual selection, one of the most important and controversial ideas in our understanding of human and animal behavior. Here’s an excerpt from an article I wrote in 2007 for Men’s Health Magazine:

Charles Darwin is of course best known for his theory that species evolve by natural selection. It holds that nature steadily weeds out unfavorable traits by killing individuals who display them, with the dirty work (or quality control) getting done by predators, natural disasters, accidents, and disease, often with considerable help from stupidity. Last year, for instance, a student writing in the University of Nebraska campus newspaper lambasted seatbelt laws as “intrusive and ridiculous,” then promptly died, unbuckled, on being flung from an SUV in a rollover. For his trouble, he got a Darwin Award, commemorating those “who improve our gene pool by removing themselves from it.” That’s natural selection.

But in his 1871 book The Descent of Man, Darwin proposed that it isn’t enough simply to avoid getting killed. Species also evolve depending on which individuals do better at attracting members of the opposite sex. This may sound obvious. But sexual selection has turned out to be far more quirky and surprising than anyone expected. Among other things, it often rewards stupid male behavior. In fact, sexual selection often puts back the very things natural selection weeds out.

Peahens, for instance, like a peacock with a big tail, precisely because the tail is costly, cumbersome, and makes him more vulnerable to predators. Is this because she wishes, once their little romantic interlude is over, that he would just go away and die?On the contrary, displays that entail high cost or danger impress because only a male with the right stuff could act like that and survive. The destiny of males, it seems, is to walk a fine line between Darwin’s two theories, showing off enough to win the admiration of females, and yet not so much that it gets you killed.

Darwin’s theory of sexual selection put primary importance on the role of female choice. For Victorian readers, that was a sticking point. Female choice challenged an orthodoxy more sacrosanct than the Biblical account of Creation: The idea that males are in charge. Thus the theory of sexual selection languished for the next 100 years, until its rediscovery and resurrection beginning in the 1960s.

One Response to “Darwin’s Other Dangerous Idea”

  1. […] Strange Behaviors: Darwin’s Other Dangerous Idea […]

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