Chimpanzees Need their Mother to Form Adequate Social Skills

Orphaned chimpanzees socialize more aggressively and for less often than those who are raised by their mother, according to new research from the Max Planck Institute for Psycholinguistics in Nijmegen, The Netherlands.

The research, published in the journal Animal Cognition indicates that orphaned chimps are less socially competent than their counterparts reared by a mother.

"Orphaned chimpanzees had more difficulties to successfully coordinate their social play interactions," said Edwin van Leeuwen from the Comparative Cognitive Anthropology Research Group at the Max Planck Institute for Psycholinguistics. "Since social play comprises a complex context in which signals about intentions need to be communicated, it seems that orphaned chimpanzees have missed out on valuable lessons from their mothers."

For their research, van Leeuwen and his colleagues studied eight orphaned chimps and nine mother-reared chimps. All the animals studied were from the Chimfunshi Wildlife Orphanage Trust in Zambia, where orphaned chimpanzees are initially cared for by humans. When the chimps are old and strong enough they are introduced to an orphan chimp group.

"The chimps in the study were between four and nine years old, so they have kind of been raising each other," said van Leeuwen, adding that the orphaned and mother-reared chimpanzees matched in age and sex.

Previous studies led the researchers to believe that the orphaned chimps would play less frequently and less smoothly than the mother-reared chimps. But in contrast to their expectations, the orphaned chimps played more frequently than mother-reared chimps, but for shorter periods of time. However, the social play of the orphaned chimps was more aggressive.

"Although the orphaned chimps were motivated to play, it seems that they were less able to coordinate their play bouts and prevent them from resulting in aggression," Van Leeuwen said.

The researchers concluded that, much like humans, the presence of a mother for chimps is important for their adequate development of social skills.

"Mothers seem to prepare their offspring for challenges that are very important for successful group-living," van Leeuwen said. "For orphans, however, the presence of other adult role models may alternatively be beneficial for boosting social competence, which is an important consideration to entertain for sanctuaries dealing with integrations of chimpanzees."