Orphaned chimpanzees are less socially competent than
chimpanzees who were reared by their mother. Researchers from the Max Planck
Institute for Psycholinguistics in Nijmegen, The Netherlands, observed that
orphaned chimpanzees frequently engaged in social play, but their play bouts
were much shorter and resulted in aggression more often. Apparently, chimpanzee
mothers endow their offspring with important social skills.