Captive chimpanzees often show abnormalities, some of which could be compared to mental illness in humans.
These include self-mutilation, repetitive rocking, as well as the eating faeces and drinking urine, according to a new study by the University of Kent.
Conducted by Nicholas Newton-Fisher and Lucy Birkett from the Kent School of Anthropology and Conservation, the research was based on 40 socially-housed zoo-living chimpanzees from six collections in the US and Britain.
After analysing 1,200 hours of data, researchers concluded that while most behaviour of zoo-living chimps is ‘normal,' abnormal behaviour is inherent in this population despite enrichment efforts such as social housing, the journal PLoS ONE reports.
Such abnormal behaviour has been attributed to the fact that many zoo-living chimpanzees occupy restricted and barren spaces compared to the natural habitat, and have large parts of their lives substantially managed by humans, according to a Kent statement. Newton-Fisher, expert in wild chimpanzee behaviour, said: “The best zoo environments, which include all zoos in this study, try hard to enrich the lives of the chimpanzees in their care.”
“Their efforts include providing unpredictable feeding schedules and extractive foraging opportunities, and opportunities for normal social interactions by housing chimpanzees in social groups.
There are limits to what zoos can provide, however; the apes are still in captivity,” he said.
“What we found in this study is that some abnormal behaviours persist despite interventions to ‘ naturalize' the captive conditions,” said Newton—Fisher.