By Science Daily, August 27, 2014
Scientists have long been searching for the factor that determines why humans often behave so selflessly. It was known that humans share this tendency with species of small Latin American primates of the family Callitrichidae (tamarins and marmosets), leading some to suggest that cooperative care for the young, which is ubiquitous in this family, was responsible for spontaneous helping behavior. But it was not so clear what other primate species do in this regard, because most studies were not comparable.
A treat is placed on a moving board outside the cage and out of the animal’s reach. With the aid of a handle, an animal can pull the board closer and bring the food within reach. However, the handle attached to the board is so far from the food that the individual operating it cannot grab the food itself. Moreover, the board instantly rolls back when the handle is released, moving the food out of reach again, which guarantees that only the other members of the group present are able to get at the snack. In this way, the researchers ensure that the animal operating the handle acts purely altruistically.
For the comparative behavior study with children, an analogous test apparatus was constructed, which was enclosed in a Plexiglas box and could be operated from outside by the children.
The above story is based on materials provided by University of Zurich. Note: Materials may be edited for content and length.
1. J. M. Burkart, O. Allon, F. Amici, C. Fichtel, C. Finkenwirth, A. Heschl, J. Huber, K. Isler, Z. K. Kosonen, E. Martins, E.J. Meulman, R. Richiger, K. Rueth, B. Spillmann, S. Wiesendanger, C. P. van Schaik. The evolutionary origin of human hyper-cooperation. Nature Communications, 2014; 5: 4747 DOI: 10.1038/ncomms5747