9 April 2009
Meat market for chimps
by Kate Melville
Newly documented observations of male and female chimps exchanging meat for mating access helps to explain how the females choose their mating partners and why the males frequently share meat with females, questions that have long puzzled scientists.
Evidence from studies on human hunter-gatherer societies suggests that the men who are more successful hunters have more wives and a larger number of offspring. One of the hypotheses proposed to explain these findings is the meat-for-sex hypothesis; however, there has been little evidence to support it.
Now, in research conducted in the Taï National Park, C�te d'Ivoire, Cristina M. Gomes and Christophe Boesch show that female chimpanzees copulate more frequently with males who share meat with them, compared with males who never share meat with them, indicating that sharing meat with females improves a males' mating success. Although the males were more likely to share meat with females who had sexual swelling (i.e. estrous females), excluding all sharing episodes with estrous females from the analysis, did not alter the results. This indicates that short term exchanges alone (i.e. within the estrous phase) cannot account for the relationship between sharing meat and mating success.
"Our results strongly suggest that wild chimpanzees exchange meat for sex, doing so on a long-term basis. 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," said Gomes.
"Our findings add to the ever-growing evidence suggesting that chimpanzees can think in the past and the future and that this influences their present behavior," added Boesch. "These findings are bound to have an impact on our current knowledge about relationships between men and women; and similar studies will determine if the direct nutritional benefits that women receive from hunters in human hunter-gatherer societies could also be driving the relationship between reproductive success and good hunting skills."
Source: Max Planck Society for the Advancement of Science