Brett Smith for redOrbit.com – Your Universe Online
You’ve probably heard the phrase “mother knows best,” but may not have realized that it applies to chimpanzees as well as humans.
According to a new study in the journal Animal Cognition, orphaned chimps have less social success than chimps that were raised by their mother.
“Orphaned chimpanzees had more difficulties to successfully coordinate their social play interactions,” said co-author Edwin van Leeuwen, a cognitive anthropologist from the Max Planck Institute in Germany. “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.”
The study was based on observation of eight orphaned and nine mother-reared juvenile chimpanzees at the Chimfunshi Wildlife Orphanage Trust in Zambia. The study researchers watched as orphaned chimps often engaged in social play, but their play sessions were much shorter and resulted in hostility more frequently.
Orphaned chimpanzees in the wildlife trust are initially cared for by humans. Once they became strong enough – typically around one or two years of age – the chimps were placed in 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,” explained van Leeuwen. Both groups of chimps were similar in age and sex, the study said.
The researchers said they had expected the orphaned chimpanzees to be less social than the mother-reared chimpanzees based on previous research. However, the orphaned chimpanzees readily engaged in social play, in fact they did so more frequently than the mother-reared juveniles, albeit for briefer periods of time.
However, the social play of the orphaned chimps resulted more frequently in aggression than social play of their peers that were raised by their mother.
“Although the orphaned chimps were motivated to play,” Van Leeuwen said, “it seems that they were less able to coordinate their play bouts and prevent them from resulting in aggression.”
The researchers said chimpanzee mothers seem to play a key role in the social development of their offspring, much like humans.
“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.”
Chimpanzees typically live in social groups called communities. Within each community, a definite social hierarchy is determined by the rank of an individual and the power the individual has on others. Male chimpanzees can move up in rank by forming alliances with others who will support their ambitions for greater power.
Female chimpanzees also have a ranking system, which is affected by the position of a female individual within a community. In some chimpanzee groups, young females may gain their high status from a high-ranking mother. Females will also use alliances to dominate lower-ranking peers. In contrast to males that seek status for mating purposes, females look to acquire dominant status for better access to resources such as food.