Researchers have found evidences that suggest that favors are exchanged among chimps and bonobos over long periods of time to build relationships.
When you let a neighbour borrow a cup of sugar from you, is your response merely give and take that characterize your long-term relationship?
"We studied the question in chimpanzees and bonobos -- our two closest living relatives -- and looked at the exchanges of grooming and food sharing, which are two common types of favours among these apes," says study co-author Adrian Jaeggi, the journal Evolution & Human Behaviour reports.
"The article focuses on the question of whether individuals do favours because they expect them to be reciprocated at some other time, and, more specifically, whether such exchanges have to happen immediately, or can take place over longer time spans," said Jaeggi, a post-doctoral anthropology researcher at the University of California - Santa Barbara (UCSB).
According to Jaeggi, while results of the research provide some evidence for immediate exchanges, they more strongly support the notion that favours are exchanged over long periods of time to develop relationships, according to an UCSB statement.
"In the chimp group we studied, we knew there was a lot of this long-term exchange," said Jaeggi.
"We didn't find any evidence for a short-term effect." They recognise others in the group, form long-term relationships, and associate with individuals who have helped them in the past.
"In the wild, for example, chimps hunt for smaller monkeys, and they commonly share the meat. It's similar to what hunters and gatherers do," Jaeggi said.
"We found that sharing was predicted by who the chimps' long-term friends and partners were," he said.
Bonobos, on the other hand, presented a different result. "Chimps would go and take food pretty confidently, but bonobos were more reticent. They'd reach out and then groom. It seemed to be that they'd groom to release tension, and then there would be these short-term reciprocal exchanges."
But even those exchanges seem to be more a by-product of the need to reduce tension, Jaeggi noted, rather than short-term contingencies used to establish reciprocity.