Zoology. Men prefer blondes, swore Howard Hawks. And the women ?, could have replicated, singing, Marilyn Monroe and Jane Russell. This question, generations of scientists have asked. By observing nature, zoologists have aligned the answers: the most beautiful, the strongest, the most enterprising, the best singers … A Sino-Dutch team has added a criterion of choice: the most intelligent. In an article published in the journal Science, these biologists establish, for the first time, a direct link between the cognitive ability of a male – in this case a parrot – and the preference displayed by the female.
Intelligence, as we know, confers an evolutionary advantage. Various studies have found, in several species, a link between brain size and longevity. Similarly, studies in sparrows and chickadees have shown that the most competent individuals in solving cognitive problems were both the most fertile and those who took the best care of their brood. Natural selection, therefore.
Nearly 150 years ago, Charles Darwin had gone further. In The descent of the man and the selection related to the sex (1871), the naturalist thought he could detect "A reinforcement (…) of our mental faculties by sexual selection ". In other words, women gave their favors to the smartest and thus doped the brains of their offspring. Only remained to demonstrate it.
This is precisely what the biologists of Peking and Leiden have undertaken to do by observing wavy parakeets. "These birds are well known, we studied their wild behavior but also their ability to social learning or the sexual selection related to plumage, says Yue-Hua Sun, professor of zoology and director of the research group on avian ecology at the Chinese Academy of Sciences. In addition, they are easy to breed in the laboratory. "
Sexual or social selection?
The researchers put each of the 17 females studied in the presence of two males and let them express their preference. This choice is expressed by the time that the lady then passes with her two suitors, and he suffers no ambiguity. The scientists then began to teach the neglected males a cognitive task, in this case to open a box in which there was food. Then they again confronted the females to the same choice, showing them this time the two males at work in front of the box, the favorite of yesterday now stumbling where his rival succeeded. Result: the parakeets have reversed their decision and opted for the vast majority for the one who appeared the smartest.