Despite chimpanzee mothers continuing to care for and transport dead infants for days, weeks, or even longer, chimpanzees find the smell of decaying corpses aversive

Putrescine-- a chemical cue of death—is aversive to chimpanzees. James R. Anderson, Hanling Yeow, Satoshi Hirata. Behavioural Processes, November 3 2021, 104538. https://doi.org/10.1016/j.beproc.2021.104538

Highlights

• In chimpanzees and other primates, mothers often carry their dead infants.

• It is unclear whether chimpanzees find the smell from decaying corpses aversive.

• We presented chimpanzees with a dead bird, a glove, and putrescine, ammonia, or water.

• Chimpanzees showed most avoidance in the putrescine condition.

• The odour of putrescine—associated with decaying corpses—is aversive to chimpanzees.

Abstract: As in many other species of nonhuman primates, chimpanzee mothers with a dead infant may continue to care for and transport the infant for days, weeks, or even longer. The bereaved females do this despite what humans perceive as the foul odour from the putrefying corpse. Putrescine is a major contributor to the “smell of death,” and it elicits behaviours aimed at getting rid of the source of the smell, or escape responses in mammals including humans. However, it has never been shown that the odour of putrescine is aversive to chimpanzees. To address this question, we visually presented six adult chimpanzees with the corpse of a small bird, or a stuffed glove, in association with putrescine, ammonia, or water, and recorded the chimpanzees’ reactions. The apes spent significantly less time near the object when it was paired with putrescine than the other substances, although they showed no signs of increased arousal or anxiety. We interpret the findings as evidence of an aversion to the smell of death in chimpanzees, discuss the implications for understanding the continued maternal-like behaviour of bereaved female chimpanzees, and suggest future research directions for the field of comparative evolutionary thanatology.

Keywords: death, mother-infant bond, olfactionPan troglodtyesthanatology