Study sheds light on how chimps understand death
Groundbreaking research from the Netherlands provides new insight into the behaviour of a chimpanzee mother after the loss of her infant. Presented in the American Journal of Primatology, the study reveals how a chimpanzee mother shows behaviours not typically seen directed toward an infant that is alive. The finding offers zoologists key information about how our closest primate relative learns about death.
Researchers at the Max Planck Institute for Psycholinguistics (MPI) found that when an infant chimpanzee dies, its mother lays it on the ground to watch it from a distance or places her fingers against its neck.
Dr Katherine Cronin and her team carried out their study at the Zambia-based Chimfunshi Wildlife Orphanage Trust, where wild-born chimpanzees reside after being rescued from illegal trade.
Scientists have long recognised that chimpanzee mothers maintain close contact with their offspring for a number of years. The infants are carried by their mothers for around two years, and are nursed until they are four to six years old. Experts say the solid ties between mother and child continue for many years after weaning. They consider this relationship as one of the most crucial in a chimpanzee's life.
Dr Cronin and doctoral student Edwin Van Leeuwen monitored the behaviour of a female chimpanzee that had recently lost her 16-month-old infant. The mother carried the infant's dead body for more than 24 hours, and then laid it on the ground in a glade. She approached the body many times, and held her fingers against the infant's face and neck for several seconds. The mother then stayed close to the body for almost an hour, later carrying it over to a group of chimpanzees that began to examine the body. The mother no longer carried the body of the infant the next day.
According to the researchers, information was seriously lacking about how primates react when their close individuals die. No information was available about whether chimpanzees mourn either.
The researchers at MPI believe they have succeeded in showing a transitional period as the chimpanzee mother learns about the death of her infant. While they avoid making interpretations about what they saw, they provide extensive video footage that gives viewers a direct link to the mother's behaviour, offering them the chance to reach their own conclusions about what chimpanzees understand about death.
'The videos are extremely valuable, because they force one to stop and think about what might be happening in the minds of other primates,' Dr Cronin explains. 'Whether a viewer ultimately decides that the chimpanzee is mourning, or simply curious about the corpse, is not nearly as important as people taking a moment to consider the possibilities,' she adds.
'These data contribute to a small but growing body of data on how non-human primates respond to death. We hope these objective accounts will continue to accumulate and eventually allow researchers to take a comprehensive look at the extent to which non-human primates understand death, and how they respond to it.'
For his part, co-author Mark Bodamer of Gonzaga University in the US says: 'Chimfunshi provides an amazing opportunity to conduct behavioural observation of chimpanzees living in large multi-age social groups in naturalistic conditions in the largest enclosures in the world, the closest to observing chimpanzees in the wild. It was only a matter of time, and the right conditions, that chimpanzees' response to death would be recorded and subjected to analysis that would reveal remarkable similarities to humans.'
The researchers say their research complements past observations and pieces together the puzzle about how chimpanzees understand mortality.
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Data Source Provider: American Journal of Primatology; Max Planck Institute for Psycholinguistics
Document Reference: Cronin, K.A., et al. (2011) Behavioral response of a chimpanzee mother toward her dead infant. AJP, published online 21 January. DOI: 10.1002/ajp.20927.
Subject Index: Coordination, Cooperation; Scientific Research; Social Aspects; Veterinary and animal sciences