Scientists studying wild Namibian chacma baboons showed that baboon mothers care, protect and carry their dead infants on average for 3 to 4 days, and up to ten days.
The research, published in Royal Society Open Science, was conducted by a team of scientists including one CNRS researcher and is part of a long-term baboon observation project in the Tsaobis Nature Park, at the edge of the Namib Desert.
The publication reports on 12 cases of group responses to infants’ deaths, including a miscarriage and two stillbirths, recorded over 13 years in wild Namibian chacma baboons. Mothers were observed to carry their dead infants for varying lengths of time and groom them frequently during this time.
Different hypotheses can explain these behaviours
The study indicates that primate mothers are aware of their infant’s death, as they treat the corpse very differently to live infants, even if they are sick and lethargic. For example, dead infants are frequently carried by a limb or dragged along the ground; this is never done with live infants.
Researchers suggest that mothers carry their infants to cope with the stress caused by the rupture of the intense social bond mothers and infants share during life. Another strong hypothesis is that carrying after death is an extension of nurturing behaviour by the mother.
One originality of the study lies in the observation of male ‘friends’ – who had been associated with the mother and her infant during its life and are usually the fathers of the infant – protecting the dead infant, either by threatening observers that came close or, on one occasion, sitting near and grooming the dead infant when the mother moved away temporarily. Dr Elise Huchard (CNRS) asserted: “This is quite surprising behaviour, because it has rarely been reported by previous studies. Male baboons are not usually very paternal.”
Travel distance and arid conditions shorten the carrying period
One of the objectives of this study was to compare the baboons’ behaviour towards dead infants with other primates such as gelada monkeys and chimpanzees. Very long corpse carriage (more than 20 days) has been observed among these species.
Researchers believe a range of factors influence the length of time a mother carries her dead infant, including the mothers’ age, infant cause of death and the climate conditions.
Dr Alecia Carter, from University College London, said: “Chacma baboons in Namibia travel much longer distances on an average day (1.8–7.7 km per day on average) and the desert environment is harsh, making it costly for a mother to carry her infant for long periods.”
Carter AJ, Baniel A, Cowlishaw G, Huchard E. 2020 Baboon thanatology: responses of filial and non-filial group members to infants’ corpses. R. Soc. open sci. 7: 192206.
Link to paper: http://dx.doi.org/10.1098/rsos.192206