Sexual selection in humans

Mr Muscle

WHY are men’s muscles so much bigger than women’s? Partly, of course, because men do the fighting and hunting. But also, perhaps, because women like men who can do these things well, and are thus attracted to muscular men. Both phenomena—competing with members of the same sex and showing off to members of the opposite—are subject to a form of evolution known as sexual selection. It is sexual selection that created the deer’s antlers and the peacock’s tail, and William Lassek of the University of Pittsburgh and Steven Gaulin of the University of California, Santa Barbara, think it explains men’s muscles as well.

The main characteristic of sexually selected features is that they are expensive to maintain. Since, whether competing or attracting, only the best will do, resources get piled into them, almost regardless of the consequences. In a study just published in Evolution and Human Behavior, Dr Lassek and Dr Gaulin show that this crucial characteristic is true for men’s muscles.

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