Chimpanzees Separated from Mothers in First Two Years of Life Show Impaired Social Behavior As Adults; Separated Chimps Who Have Since Lived in Social Groups for 40 Years Still Show Impaired Behavior

Wild-caught chimpanzees, who were orphaned and imported from Africa in their early infancy, exhibit impaired social behavior, even as adults, and even when living in social groups for many years. So far, long-term effects of early traumatic experiences on social behavior were known only for humans and socially isolated chimpanzees. An Austrian-Dutch research team, led by Elfriede Kalcher-Sommersguter, Ph.D., of the University of Graz and Jorg Massen. Ph.D., of both the University of Vienna and Utrecht University, published these results online on November 10, 2015 in Scientific Reports. The article is titled “Early Maternal Loss Affects Social Integration of Chimpanzees Throughout Their Lifetime.” Between 1950 and 1980, thousands of chimpanzee infants were wild-caught in West Africa and exported to Europe, Japan, and the USA, where these chimpanzees have been used in biomedical research. But also many zoos have wild-caught chimpanzees: the so-called founder populations. The new study shows that chimpanzees, who were maternally deprived within their first two years of life, were restricted in their social grooming behavior, even decades later. Social grooming is highly important for the establishment and maintenance of social relationships within groups of chimpanzees. "The orphaned chimpanzees had a lower number of partners they groomed and were less active than were chimpanzees reared by their mothers," says Dr. Kalcher-Sommersguter. These deficits in social grooming are found, not only in chimpanzees that were kept singly caged for decades in a biomedical laboratory, before being re-socialized, but also in individuals, who, after being orphaned, grew up in social groups in a zoo.
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