Looking compensates for the distance between mother and infant chimpanzee.

The development of visual interaction between mother and infant has received much attention in developmental psychology, not only in humans, but also in non-human primates. Recently, comparative developmental approaches have investigated whether the mechanisms that underlie these behaviors are common in primates. In the present study, we focused on the question of whether chimpanzee mother and infant replace physical contact with visual contact. To test this hypothesis, we measured non-synchronous looking ('looking') between mother and infant. A unique setting, in which the mother chimpanzee stayed in one location and the infant chimpanzee moved freely, allowed us to analyze the relation between the visual interaction and the distance of a mother-infant pair during the first year of life. Our results showed that 'looking' increased when body contact decreased or when the distance between mother and infant increased. We also show a behavioral sequence of typical 'secure base' behavior, a behavior characterized by the infant regularly returning to its mother when exploring the environment. These findings imply that attachment between mother and infant chimpanzee appears to develop in a similar fashion as in humans.