'Peter Pan' Apes Never Seem To Learn Selfishness

Feb 01, 2010 By Karl Leif Bates
A juvenile bonobo in the Democratic Republic of Congo. Image: Vanessa Woods

(PhysOrg.com) -- Sharing is a behavior on which day care workers and kindergarten teachers tend to offer young humans a lot of coaching. But for our ape cousins the bonobos, sharing just comes naturally.

In fact, according to a pair of papers in the latest , it looks like bonobos never seem to learn how not to share. Chimpanzees, by contrast, are notorious for hogging food to themselves, by if necessary. While chimps will share as youngsters, they grow out of it.

In several experiments to measure food-sharing and social inhibition among chimps and bonobos living in African sanctuaries, researchers from Duke and Harvard say these behavioral differences may be rooted in developmental patterns that portray something about the historical lifestyles of these two closely related apes.

When compared with chimps, bonobos seem to be living in "a sort of Peter Pan world," said Brian Hare, an assistant professor of at Duke University, who participated in both studies. "They never grow up, and they share."

Hare and his mentor, Richard Wrangham, the Ruth Moore Professor of Anthropology at Harvard, think this kinder, gentler ape's behavior has been shaped by the relative abundance of their environment. Living south of the Congo River, where food is more plentiful, bonobos don't compete with gorillas for food as chimps have to, and they don't have to compete much with each other either.

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Bonobos Like To Share

In essence, they don't have to grow up, Hare said, and cognitive tests that the team performed on the captive animals seem to bear that out. Bonobos shared like juveniles even after they reached adulthood.

"It seems like some of these adult differences might actually derive from developmental differences," said Harvard graduate student Victoria Wobber, who is the lead author on one of the papers. "Evolution has been acting on the development of their cognition."

To measure sharing behavior, paired animals at the Tchimpounga Sanctuary in the Republic of the Congo were put into an enclosure with some food. Younger chimps were found to be quite similar to young bonobos in their willingness to share food, but the chimps become less willing to share when they're older.

In a second set of sharing experiments, Hare and a colleague at the Lola ya Bonobo sanctuary near Kinshasa, Democratic Republic of Congo gave bonobos an opportunity to have all of a food pile to themselves while a fellow bonobo watched helplessly from behind a gate. Instead, the subjects universally preferred to open the gate and let their friends share. Their friends weren't even begging or carrying on. (See YouTube video: www.youtube.com/watch?v=sRDc4SCaFLQ )

"A chimp would never voluntarily do that," Hare said. "Chimps will do things to help one another, but the one thing they will not do is share food."

In a series of tests on how socially savvy the apes were about asking others for handouts, the chimps were quick studies, but the bonobos never quite got the hang of it. In chimp society, where hogging the food pile is a privilege of rank, younger animals have to learn which adults can be begged from and which cannot, Wobber said.

In one test of social skills, Wobber had two humans hold treats concealed in their hands, while a third human was empty-handed. The animals were encouraged to ask for a treat by touching the hands. The chimps quickly picked up on the pattern and didn't bother begging from the empty-handed person. The bonobos were less discriminating and tried the empty hand just as much as the full ones.

A second social experiment used two people, one with a treat and one without. After the apes had it figured out, the treats were moved to the other human. The caught on to the new pattern much more quickly than the bonobos.

These experiments don't mean the are less smart, Wobber said. It's just that they're less attuned to the social inhibitions a chimp would need to successfully share food without being slapped on the head.

The findings fit into a larger picture that Hare and Wrangham have been building in which animals that have been domesticated, such as pet dogs and arctic foxes in a long-term experiment in Siberia, possess what could be considered juvenile physical traits and behaviors, even after they've reached sexual maturity. It's an example, they say, of selection acting against aggression. Their behaviors are more juvenile, and so too are their physical features.

Explore further: Lemurs match scent of a friend to sound of her voice

More information: www.cell.com/current-biology/abstract/S0960-9822%2809%2902141-1

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User comments : 6

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Mercury_01
4.7 / 5 (3) Feb 01, 2010
This species needs to get a lot more attention from behaviorists now that the congo is more accessible. We share a gene related to social behavior with the bonobo that we do not share with the chimp. Personally, Im tired of the notion that humans are selfish and violent by nature.

There is a story of a bonobo who found a starling in her enclosure that had flown into a window and was stunned. The ape took the bird to a high point and attempted to help the bird by opening up its wings and tossing it into the air. I havent heard this kind of thing in any of the discussions on altruism. this species is different from any animal on earth.
quixote7
5 / 5 (3) Feb 01, 2010
Humans retain even more juvenile characteristics into adulthood than bonobos. Since they're more similar to us, it makes me wonder why they're not the main species for clues about behavior that can be extrapolated to humans. Instead, even ants get more press. Maybe the problem is that bonobos don't lend themselves to a macho narrative.
Mercury_01
not rated yet Feb 02, 2010
What I understand is that around the time that science began to popularize behavior studies with the chimpanzee, the only area that the bonobo lives was plunged into civil war, halting 20 years of data collection that was only recently resumed. chimps were simply easier subjects to study, and they were first in front of the camera.
PinkElephant
5 / 5 (1) Feb 02, 2010
Another somewhat unique aspect of bonobos (on which the article didn't touch, as it's not very relevant to the subject matter), is that they are sexually extremely promiscuous. They use sex in the same way as chimps use grooming: just as a way to improve group cohesion. Adults routinely molest children. Homosexual sex is very common. Confrontations that would result in fights among chimps, instead are resolved through sex among bonobos. Rather uniquely, bonobos engage in face-to-face sex, kissing, and even oral sex. Their societies are matriarchal, instead of patriarchal like most other apes. Bonobos are like the ultimate primate hippies...

Obviously, such a behavioral feature won't be a popular item for expose amid uptight societies ruled by vestigial Puritanical moral codes. This might well be the real reason why chimps get so much more press than bonobos...
Caliban
1 / 5 (1) Feb 02, 2010
Interesting that any inferred common ancestor here(shared with humans) would have given rise to a bifurcated pair of very similar lineages(morphologically), that were so different behaviorally. Wonder if something very, very similar didn't happen in the development of human lineage(s). And, is there any evidence of fertile Chimp/Bonobo crosses?
seneca
not rated yet Feb 02, 2010
Sharing is communism...;-)
http://rlv.zcache..._210.jpg

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