What's mine is yours, kind of: Bonobos and the thorny evolving roots of sharing

An intriguing study published this week suggests that bonobos, among the closest relatives of humans, are surprisingly willing to give food to a friend. But they did not share any tools.

The discovery adds a new twist to scientists' efforts to understand the evolving origins of people's unusual propensity to help others.

"One of the things that really strikes humans is how cooperative or helpful we are," says Christopher Krupenye, an evolutionary anthropologist at the University of St. Andrews in Scotland. "It's just a really pervasive element of our behavior."

Common chimpanzees (a related species that diverged from bonobos about 2 million years ago) have an altruistic behavior. For example, it has been shown that chimpanzees will deliver a tool out of reach to someone who is clearly trying to get it – just like human children. So, Krupenye and some colleagues have recently repeated this experience with bonobos.

"Bonobos did not help at all," says Krupenye. Instead, they sometimes picked up the tool but kept it out of reach, showing it mockingly. "They did not help, in this particular context."

He and his colleagues then conducted another series of experiments involving palm nuts, which bonobos usually crack with rocks. Two bonobos were put in cages side by side, with a window in between.

"We gave one individual several nuts, and the other several stones, and we wanted to see if they would help each other," says Krupenye. "Any one of them could transfer his surplus resources to help his partner."

Bonobos showed very little motivation to hand over stones, again suggesting that sharing tools or objects was not part of their normal routine. "They just do not seem to show that kind of behavior," says Krupenye.

But they have always shared nuts – even though they could easily have kept the nuts for themselves. And it is very different from what is observed among chimpanzees, researchers report Tuesday in the newspaper. Acts of the Royal Society B.

In the wild, food sharing by chimpanzees usually occurs after a rare hunt and the "sharing" of meat often involves passive tolerance of theft or simply implacable begging and harassment of others.

On the other hand, the bonobos have voluntarily put back nuts in their possession.

"What we see in bonobos is very unusual," says Krupenye. "We see the sharing of food in other species, but in the vast majority of cases, it is a person who tolerates another who takes something."

The discovery adds to a growing body of evidence that bonobos are only pro-social in terms of diet, says Zanna Clay, a primatologist at the University of Durham in the UK.

"One thing that seems to be special about bonobos, is that they do not seem to have as much competition as chimpanzees around food," says Clay, who notes that even the bonobos of different communities will share food. food, like meat.

In addition, the voluntary voluntary surrender of food products, as the bonobos did in this study, is special. "Normally, this happens between mothers and infants, in most species," she says. "It's really very unusual in animals."

It is unclear why bonobos would not share tools similarly, but Clay points out that "in the wild, bonobos do not use tools".

Joan Silk, a primatologist at the University of Arizona, says she found the document surprising and would like to see the results reproduced in several groups of bonobos.

"If we discover that chimpanzees are more likely to exchange tools than bonobos, then I do not know what we would think," says Silk, noting that chimpanzees may have a different understanding of the value of tools simply because they use them the most.

Sharing is a much more important part of human life than other monkeys, adds Silk; but researchers do not yet know if the difference is simply quantitative or if humans approach sharing and help in a fundamentally different way.

Young children have a surprising willingness to share, says Silk – even if it may surprise parents who must constantly remind their children to do so.

"Children are very generous," insists Silk, who has studied sharing behavior, not only in chimpanzees but also in young children.

"Compared to chimpanzees," she says, "your children are saints."

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