Fongoli chimpanzees also frequently share food and hunting tools with other chimps just like human beings, a new study has claimed.
According to Jill Pruetz from Iowa State University, sharing food has widely been considered by scholars as a defining characteristic of human behaviour, but chimpanzees from her Fongoli research site in Senegal also exhibit the sharing tendency.
The researchers witnessed 41 cases of Fongoli chimpanzees willingly transferring either wild plant foods or hunting tools to other chimpanzees.
“They’re the Fongoli chimps not the only chimps that share, but in terms of the resources that we cover here, that is unique,” Pruetz said.
“I guess all chimps share meat, but they don’t share plants or tools. Yet they do here, in addition to meat. It was intriguing when we first started seeing these events,” she said.
The researchers document a frequency of sharing previously unreported for chimpanzees. The chimps commonly transferred meat and wild plant foods, but they also transferred tools, honey and soil.
Most of the transfer behavior was classified as recovery or passive sharing, with females commonly taking food from males — with much of that taking place from dominant to subordinate recipients.
In the new study, of the 41 witnessed events, Fongoli male chimps transferred wild foods or tools to females 27 times.
“It’s a different set of relationships within the social group at the Fongoli site, and I tend to think again that it ties back to the environment and the fact that the resources are distributed differently.
“They have a big home range — about 10 times bigger than Jane Goodall’s range in Gombe at 86 square kilometers — and that forces them to stay together. If they split up like chimps normally do, it could be days or weeks or months before they may see someone again — and chimps are more social than that. So I think they stay together like monkeys and they move around their home range together,” she said.
Pruetz sees some of the sharing behaviour between males and females as a product of the “food for sex” theory. The ISU researchers found that both adult females in estrus [the period of maximum sexual receptivity of the female] and adolescent females cycling to estrus were more likely to receive food from adult male chimps.
She also said that the male chimps may use food transfer as a future mating strategy with the adolescent females, particularly since there are a relatively small number of females in the Fongoli community.
“It may be used as a strategy [by the male chimps], anticipating a long-term gain on their behaviour. We see that in baboons who have special friends,” she said.
As the only habituated community of chimpanzees living in a savanna environment, the researchers conclude that Fongoli provides detailed information on the effect of an open, dry and hot environment on social behavior and organization.
The study has been published online in Primates.