Beauty doesn’t only fade within a lifetime–it also fades genetically over the course of several generations, according to new research. Scientists studying populations of sexually attractive male fruit flies have found that there’s a limit to their evolutionary success–and that there may actually be a disadvantage to being too sexy.
For the study, published in the Proceedings of the National Academy of Sciences, researchers genetically modified male fruit flies, causing them to give off excessive amounts of attractive pheromones. The scientists then introduced a flock of these foxy fellows to a normal fruit fly population. They discovered that the female flies mated with these modified flies more often initially, and the proportion of super-sexy males increased for a while–but the proportions returned to normal after seven generations.
“Even though we were able to make males more attractive, there must have been a fitness cost,” said Katrina McGuigan, a biologist at the University of Queensland and one of the study’s authors. “While sexual selection is really powerful, there are consequences to nonsexual traits.”
It’s not yet clear what genetic disadvantage these fruit fly ladykillers may have had. But let’s turn to the more urgent question: Is there any carryover implications for humans? The New York Times quotes McGuigan:
“Hard to say, but only that very attractive individuals may well have something wrong with them — they may not be as good as they seem to be at first glance.”
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Image: Wikimedia Commons / A. O’Toole