It goes without saying that we share sweets or other things with friends. Not so with the bonobos: Before choosing whether they share their food with a known or an unknown conspecific, they usually opt for the stranger. This is shown by an experiment by American researchers with bonobos in a protected area in the Democratic Republic of Congo, about which they report in the trade magazine "PloS ONE". In nine out of ten cases, the bonobos did not give access to food to the known group member, but to the stranger - even if they themselves ran out of food.
For the normally very social apes, at first glance this would be an unusual behavior. "It seems crazy to us, but the bonobos expand their social network in this way, " explains study director Brian Hare from Duke University. Sharing the food helps build a social relationship with an unknown animal. In the case of the already known conspecifics, on the other hand, that would obviously not be necessary. In this strategic social behavior, the bonobos differ significantly from the closely related chimpanzees, but also from humans. Because we tend to serve our friends first, then a stranger first.
Three enclosures and a feed pile
For their study, the researchers performed three experimental variants with 14 bonobos from the Lola ya Bonobo Sanctuary near the city of Kinshasa. In the first test, the scientists placed a feed pile in a central enclosure with a bonobo. In two adjacent enclosures were a member of the same group of monkeys and one of the test bonobo foreign species. The bonobo was now able to decide if he would eat the food alone or open the door to one or both of his fellows, giving him access to the central enclosure and the food. display
As the researchers report, nine out of 14 bonobos left the strange conspecifics out of his enclosure and shared the food with him. In many cases it was then the stranger who then also the third bonobo opened the door and granted him access to the food. This behavior is also unusual, explains first author Jingzhi Tan from Duke University. Because with that, the stranger voluntarily exposes himself to the preponderance of two familiar bonobos. "A chimpanzee would never do that, " Tan says. In addition, there had not even been any aggressive reactions between the bonobos in the total of 51 test runs.
In a second test, although the bonobos were able to gain access to the food for one of the other two monkeys, they were sitting in another enclosure themselves and therefore did not receive any of it themselves. In this case, nine out of ten animals decided at least once to open the door to food for their unknown counterparts instead of their group member.
No sharing with anonymous recipients
The situation changed, however, in the third test. The bonobos lost food when they decided to share, but did not get a chance to get in touch with their conspecifics. The result: They did not give any of the two conspecifics access to the food. "If they have no social benefit, the bonobos do not share either, " explains Hare. They are only willing to accept losses if they can then come in contact with the conspecifics. In this point, the bonobo is different from the human, because this often give off even if he does not know the recipient personally, for example, during a donation or in the game experiment. "Bonobos also take care of others - but only if they have something of it, " says Hare.Jingzhi Tan, Brian Hare (Duke University): PloS ONE, doi: 10.1371 / journal.pone.0051922 © science.de - === Nadja Podbregar