Development of tool-use to obtain food in a captive group of Macaca tonkeana

Abstract

Members of a captive group of Macaca Tonkeana were given the opportunity to use a metal rod to obtain honey which was out of direct reach. Two adolescent males spontaneously learned to use the rod to reach the honey. Learning by the second male appeared to be facilitated through joint manipulation of the rod with the first male to acquire the behaviour. The mothers of these two males contacted the rod more after their sons had learned to use it for getting honey, but none of the adults or juveniles in the group learned to use the rod. The failure of the other members to acquire the new behaviour can be interpreted in terms of the conservatism of adults and the fact that the two adolescents tended to monopolize working with the rod once they had knowledge of its value.