It’s been a truism since Darwin’s day: Female peahens prefer a male peacock with a gorgeous train–the fancy feathered fan he unfurls to wow the gals. But a new 7-year study questions this long-held notion, reporting that females in a feral population of Indian peafowl (Pavo cristatus) showed no such preference. The controversial paper contradicts previous, lauded studies that did reveal a link and that are part of the canon of evolutionary biology. Because natural selection cannot explain the evolution of seemingly useless male ornaments, such as elaborate feathers, Charles Darwin proposed that they arise through sexual selection. In most species, females choose the male they want to mate with, presumably by evaluating traits that give clues to genetic health. For example, the peacock’s train is longer than his body and decorated with gaudy eyespots. The number of eyespots may correlate with the quality of the male’s genes, so a female peahen should pick the fellow with the highest count. In the most cited study of the peacock’s train, evolutionary biologist Marion Petrie of Newcastle University in the U. K. snipped off the eyespot portion of some males’ tail feathers; the females snubbed these males. Furthermore, chicks fathered by more ornamented males had higher long-term survival than other chicks.
Mariko Takahashi’s team planned to confirm these results. But despite observing 268 matings, the team was unable to pinpoint any single male trait that females preferred, they report in April’s issue of Animal Behaviour.