Human females may get offended at dates who expect a little something extra after they buy a steak dinner, but for chimpanzees, the exchange may be a fair one [Reuters]. A new study of a chimp community living in the western African nation Côte d’Ivoire has found that males regularly share meat from their hunting expeditions with females, and get sex in return.
The researchers observed males sharing meat with females in estrus, who have sexual swellings that indicate their current fertility. More surprising was that males shared meat with females that didn’t have sexual swellings, perhaps in hopes of future success, the researchers say. The sex “may not necessarily occur immediately—it could occur sometime in the future,” said study co-author Cristina M. Gomes [National Geographic News]. The findings, she says, support the theory that chimps can engage in long-term planning, anticipating future events and remembering past interactions.
The chimpanzees’ diet consists mostly of fruits and vegetables, but meat is an occasional, protein-rich treat. Researchers have long known that wild chimps — mainly males — occasionally form hunting parties to chase down and kill colobus monkeys and other animals. Hunters eat much, but not all, of the meat obtained in this way [Science News].
Previous studies had suggested that the hunting males shared meat with females in estrus, but those studies were too short to determine long-term effects. The new study, published in the journal PLoS ONE, followed the group of chimps for three years. Researchers observed 90 successful monkey hunts, as well as subsequent meat sharing and mating. In the end, the researchers found that males “who shared meat with females doubled their mating success, whereas females, who had difficulty obtaining meat on their own, increased their caloric intake without suffering the energetic costs and potential risk of injury related to hunting” [Reuters], says Gomes.
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Image: Cristina M. Gomes