Lemurs: Cleverness makes friends

Successful primates are more populous in the group

Kattas like to surround themselves with successful conspecifics. © Ipek G. Kulahci
Read out

Popular thanks to success: Lemurs obviously choose their friends for their abilities. An experiment shows that primates that prove to be clever in difficult tasks, are scrambled and peed more intensely by other group members - a thoroughly sensible strategy. Because the grooming strengthens the social bond and thus the chance to benefit from the success of the other.

We share the same interests, have common tastes, and laugh about the same things: we often look for people as friends who are similar in many ways to us. But it's not just similarities that decide who we surround ourselves with. Even if it does not sound very romantic, the benefits of a relationship are sometimes just as important.

After all, who does not have it: the clever friend who always helps out with math problems, the athletic friend who motivates to go to the gym or the winner-type friend, from whose splendor we hope to have a certain radiance? Scientists led by Ipek Kulahci at Princeton University have now discovered that such factors are not only important in human social systems. Other primates apparently seek their friends on similar principles.

Who breaks the puzzle?

For their study, the researchers observed free-living kattas on St. Catherines Island in the US state of Georgia. The red-tailed lemurs are otherwise found only in Madagascar in the wild, but a population was introduced on the American island in the 1980s for research purposes. As in their original homeland, the primates live there in associations of 20 to 30 animals.

In the area of ​​two of these groups, Kulahci and her colleagues set up a plexiglas box. Anyone who was skilled and learned to open the box could get as a reward to a contained grape. How would the Kattas interact with the box and with each other? display

More grooming thanks to success

It turned out: Social well-connected lemurs solved the task more often than other animals. At the same time, however: if a katta had grabbed the grape and others had observed this success, he was then in the group much more popular. "These lemurs were given more attachment-promoting behavior such as scratching or grooming - without adjusting their own social behavior, " says Kulahci.

This is astounding because coat care in primates is usually based on the principle of reciprocity. Who wants to be gekrault and gelaust, must do the same with the counterpart. Only dominant individuals often receive increased attention without reciprocating the favor. "So it's a remarkable pattern that watching successful animals receive more grooming without any return, " says Kulahci.

Learning from friends

Knowing and succeeding influences the position of an animal within the social network. According to the researchers, this relationship has not yet been shown in any study. Earlier studies have already suggested that social relationships control the dissemination of information within a primate group. But no one had considered the flip side: how learning and information change the structures of the social fabric.

For the Kattas, this adaptation of social behavior makes sense: "Being socially well-connected with successful individuals increases the chances of learning from these individuals, copying them, and later on becoming more successful" concludes Kulahci. As with us ... (Current Biology, 2018; doi: 10.1016 / j.cub.2018.02.079)

(Princeton University, 06.04.2018 - DAL)