Bonobos Share With Strangers To Get Better Acquainted
January 3, 2013

Bonobos Share With Strangers To Get Better Acquainted

Brett Smith for - Your Universe Online

When given the chance to share something, do you turn to a friend or a stranger with your offer of generosity? Do you look to make a connection with an unknown somebody or do you look to strengthen a bond with someone familiar?

We primates are social animals and a pair of researchers from Duke University recently decided to look into how one group of primates, bonobos, approach this question of who to share with, and why.

According to their report in the open access journal PLoS ONE, the researchers found that the bonobos in their study preferred to share with strangers, over bonobos they were familiar with–the opposite of the behavior exhibited by most humans.

"It seems kind of crazy to us, but bonobos prefer to share with strangers," said Brian Hare, a professor of evolutionary anthropology at Duke. "They're trying to extend their social network."

To reach these conclusions, Hare and his partner Jingzhi Tan conducted a series of experiments with bonobos living in the Lola ya Bonobo sanctuary in Kinshasa, Democratic Republic of Congo.

In the first experiment, food was placed in a central enclosure, which was connected to two enclosures that each held a bonobo. The test subject was let into the central enclosure and had the ability to open either or both of the connecting enclosures. On one side was a bonobo that was an acquaintance from their group and in the other was a bonobo they had never met, but had seen from a distance.

Hare and Tan designed the setup to give the test subject three choices: share first with an acquaintance, share first with a stranger, or share with neither. They watched as 9 of the 14 animals released the stranger first, while two preferred the bonobo from their group and three showed no particular preference over the course of several trials.

Interestingly, the third bonobo was often allowed to join in on the snack, but often it was the stranger who opened the door for the subject´s acquaintance. Tan said this behavior was unique because the stranger knowingly outnumbered himself or herself with two bonobos who were familiar with each other.

The researchers ran a second set of experiments in which the subject primate wouldn't receive any social contact with another animal in order to see how much the reward of social interaction plays in the bonobo decision making process.

The first “no-contact” experiment was designed so that the subjects couldn't get any food for themselves despite whether or not they allowed another animal to get some food. In this phase, nine out of ten bonobos shared with the stranger at least once.

In the second “no-contact” experiment, the test subject was given access to the food, but opening an enclosure to share with another animal would cost them some food. In this situation, the animals chose not to share.

"If they're not going to see a social benefit, they won't share," Hare explained in a statement.

According to Hare, the second “no-contact” test was patterned after something called the Dictator Game, in which humans are given the chance to share money with a stranger. In the game, most people will share anonymously, but they tend to share an even greater amount when they aren't anonymous. Contrary to this behavior in humans, bonobos won't share at all in the anonymous condition if it costs them food.

"They care about others," Hare concluded, but only in a sort of selfish way. "They'll share when it's a low-cost/low-benefit kind of situation. But when it's a no-benefit situation, they won't share. That's different from a human playing the dictator game. You really have to care about others to give anonymously."