New York - From scientific studies to sitcoms, society portrays men as wired to prefer sexual flings and spurn commitment, and evolution wanted it that way. In a study published on Tuesday, anthropologists present evidence that male promiscuity is not a human universal wired into the brain by evolution. Instead, mating strategies are flexible, responding to circumstances such as gender ratios. In short, when women are scarce, men prefer long-term committed relationships, said Ryan Schacht of the University of Utah, who led the study published in Royal Society Open Science. And women, contrary to stereotype, can be just as interested in one-night stands. The idea that evolution shaped men to be Lotharios seemed solidly grounded in theory. The more women a man had sex with, and the less he tied himself to one woman and their children, goes the argument, the more offspring to whom he would pass on his genes, the measure of evolutionary success. In experiments, male college students typically said they preferred flings to commitment, leading to the claim that the behaviour was wired in by evolution. Schacht and Monique Borgerhoff Mulder of the University of California, Davis, tested that idea in the Makushi, Amerindians of Guyana. In the eight communities they examined, the ratio of adult men to women varied from 1.43 to 0.93. The more men outnumbered women, the less likely they were to fit stereotypical, flings-over-commitment behaviour. That makes evolutionary sense, Schacht said. For one thing, commitment increases the number of "mating opportunities" men have compared to when they have to keep attracting new partners. "The best strategy is to find one woman and stick with her," Schacht said. Infidelity and promiscuity defeat that. In addition, while natural selection favours behaviours that increase a man's number of children, it favours even more strongly behaviours that maximize those who grow up and become parents themselves. That is more likely, Schacht said, when men stick around to protect and provide rather than moving from fling to fling. A prominent proponent of evolutionary psychology, the field associated with the idea that men are wired for one-night stands, said the new findings "largely comport well" with findings of evolutionary psychologists. Contrary to stereotypes, said David Buss of the University of Texas, "no one has argued that 'men are ardent and women coy.'" Which mating strategy men adopt "depends heavily on context."