Dead infant carrying by chimpanzee mothers in the Budongo Forest

Abstract

ABSTRACTIt has been suggested that non-human primates (hereafter primates) can respond to deceased conspecifics in ways that suggest they experience psychological states not unlike humans, which would indicate they exhibit some notion of death. Here, we report long-term demographic data from two East African chimpanzee groups. During a combined 40-year observation period we recorded 191 births of which around a third died in infancy, mostly within the first year. We documented the post-mortem behaviour of the mothers and found that Budongo chimpanzee mothers routinely carried deceased infants after their death, usually until the body started to decompose after a few days. However, we also observed three cases of extended carrying lasting for more than 2-weeks, one of which was followed by the unusual extended carrying of a substitute object and another which lasted three months. In each case, the corpses mummified. We discuss these data in view of functional hypotheses of dead infant carrying in primates and the potential proximate mechanisms involved in this behaviour, including psychological processes managing infant loss in humans such as grieving.