"At first glance, the 'sexy son hypothesis' makes perfect sense. According to this pillar of evolutionary biology, a female who chooses a high-quality male will have sons who inherit dad's allure. They, too, will therefore have their pick of females, allowing mom to hit the jackpot: grandmotherhood.
But when scientists followed male flycatchers whose dads were real catches (as judged by a forehead patch that is this bird's equivalent of perfect abs), they found no such thing.
The sons 'did not inherit their father's ... mating status,' the Swedish researchers wrote in the February issue of American Naturalist. As a result, mom got fewer grandkids than did females who settled for less-attractive males. The studs were so busy mating they had no time to raise offspring, causing their health and fecundity to suffer. Homelier birds were better dads, raising sons who had more mating success."
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