Early life experiences: activity levels and abnormal behaviours in resocialised chimpanzees
Chimpanzees (pan troglodytes) that are kept in captivity come from a wide variety of backgrounds, and a proportion of them have been subjected to maternal separation and social deprivation during development. The long-term effects of such practices have received little investigation.
This study investigates whether the removal of infants from their mothers and/or other chimpanzees affects their activity levels and abnormal behaviours later in life. A total of 69 resocialised chimpanzees were studied at six zoos in the United Kingdom. Chimpanzees were categorised into one
of three rearing conditions: reared by their mother in a group of conspecifics (MGR); reared with other conspecifics but separated from their mothers (RO); and reared apart from their mother or other conspecifics for a period of time during infancy (RA). Results indicate that 'socially deprived'
individuals show reduced levels of normal activity, elevated levels of abnormal behaviours and a wider repertoire of abnormal behaviours. These differences were more pronounced in younger individuals, with adults from the three different rearing conditions performing abnormal behaviour patterns
at comparable levels. It is concluded that human-rearing, either alone or with conspecifics, influences behaviour through suppression of normal activity levels as a result of separation and elevation of levels of abnormal behaviours as a mechanism for coping with maternal loss and restricted
rearing. However, these effects are not irreversible and recovery of 'normal' behaviours may occur with access to an enriched social environment.