Sorry, ladies, a world full of Johnny Depps is just not sustainable. Too many attractive males, and evolutionary pressures start to select against the best-looking, researchers report online today in the Proceedings of the National Academies of Science. The researchers genetically engineered a group of male flies to release highly attractive pheromones and then released a large number of them into a colony so that they greatly outnumbered average males. Predictably, the females went for the sexier flies—at least at first. After seven generations, however, the numbers of attractive and average flies had leveled out. The authors conclude that being overly attractive must carry a disadvantage , similar to how a male peacock's large, colorful tail hinders its ability to flee and hide from predators. And that limits how many handsome men can exist in a population.
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