Chimpanzees Share Forbidden Fruit (9/13/2007)

They say that the way to a man's heart is through his stomach and the same could be said for female chimpanzees. Researchers studying wild chimps in West Africa have discovered that males pinch desirable fruits from local farms and orchards as a means of attracting female mates.

Lead researcher, Dr Kimberley Hockings from the University of Stirling's Department of Psychology said: "We believe the males may be using crop-raids as a way to advertise their prowess to other group-members, especially the opposite sex. Such daring behaviour certainly seems to be an attractive trait and possessing a sought-after food item, such as papaya, appears to draw even more positive attention from the females."

The study, which took place in the West African village of Bossou in the Republic of Guinea, is the only recorded example of regular sharing of plant foods by unrelated, non-provisioned wild chimpanzees.

Dr Hockings explained: "It is unusual behaviour as even though the major part of chimpanzees' diets consists of plant foods, wild plant food sharing (defined as an individual holding a food item but allowing another individual to consume part of that item) occurs infrequently. However, in chimpanzee communities that engage in hunting, meat is frequently used as a 'social tool' for nurturing alliances and social bonds. This research shows that chimpanzees at Bossou use crop-raiding as an opportunity to obtain and share desirable foods, providing further insights into the evolutionary basis of human food sharing. In humans, the pursuit of certain foods is also strongly sex-biased; for example, it has been proposed that men in hunter-gatherer societies acquire large and risky-to-obtain food packages for social strategising and to garner attention."

The researchers found that adult males mainly shared the spoils of their crop-raids with females of reproductive age; particularly with a female within the group who took part in most consortships (where an adult female and an adult male chimpanzee move to the periphery of their community so that the male gains exclusive mating access).

Dr Hockings said: "The male who shared the most food with this female engaged in more consortships with her and received more grooming from her than the other males, even the alpha male. Therefore the male chimpanzees appear to be 'showing off' and trading their forbidden fruit for other currencies, i.e. 'food-for-sex and -grooming'."

The full paper will published in the Public Library of Science's journal, PLoS ONE on Wednesday 12 September: www.plosone.org (opens in new window) where video clips of the chimps can also be viewed.

Note: This story has been adapted from a news release issued by the University of Stirling

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