The study of non-human primate thanatology has expanded dramatically in recent years as scientists seek to understand the evolutionary roots of human death concepts and practices. However, observations of how conspecifics respond to dead individuals are rare and highly variable. Mothers of several species of primate have been reported to carry and continue to interact with dead infants. Such interactions have been proposed to be related to maternal condition, attachment, environmental conditions or reflect a lack of awareness that the infant has died. Here, we tested these hypotheses using a dataset of cases of infant corpse carrying by chimpanzees in Gombe National Park, Tanzania (n = 33), the largest dataset of such cases in chimpanzees. We found that mothers carried infant corpses at high rates, despite behavioural evidence that they recognize that death has occurred. Median duration of carriage was 1.83 days (interquartile range = 1.03-3.59). Using an information theoretic approach, we found no support for any of the leading hypotheses for duration of continued carriage. We interpret these data in the context of recent discussions regarding what non-human primates understand about death.
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Ethics. This work was observational and non-invasive, and complies with the Association for the Study of Animal Behaviour Guidelines for the Use of Animals in Research. In addition, all work complied with the legal and permitting requirements of the government of Tanzania, where the work was carried out. Data accessibility. The datasets supporting this article are available in the electronic supplementary material. Authors’ contribution. E.V.L. conceived and designed the study, analysed the data and drafted the manuscript. M.L.W. and A.E.P. helped to design the study and contributed data. E.B., J.D.-S., T.G., C.M. and K.W. contributed data and assisted with data acquisition. All authors were involved in revising the manuscript and approving of its final form. Competing interests. The authors declare no competing interests. Funding. This work was supported by funds from the National Institutes of Health (grant no. 5R00HD057992, R01 AI50529, R01 AI58715), the National Science Foundation (grant nos. DBS-9021946, SBR-9319909, BCS-0452315, IOS LTREB-1052693, 1457260 BCS-1753437), the Leo S. Guthman Foundation, the National Geographic Society, the Harris Steel Group, the Windibrow Foundation, the Carnegie Corporation, the University of Minnesota, Franklin and Marshall College, George Washington University and Duke University. Funding for open access provided by the Franklin & Marshall College Open Access Publishing Fund. Acknowledgements. The authors thank Jane Goodall, the Jane Goodall Institute and Tanzania National Parks (TANAPA) for initiating and continuing the over 59-year research tradition at Gombe. We are extremely grateful to the Gombe Stream Research Centre assistants for data collection. Thanks are also due to Anthony Collins and Deus Mjungu for their continued dedication to long-term data collection at Gombe and to Shannon Rovias for assistance with case extraction from the data archive. Special thanks to Hank Klein, Maria Botero, Emily Wroblewski and Kelly Ostrofsky for sharing their field notes for key cases and to Margaret Stanton for statistical advice. Permission and support to carry out research at Gombe was granted by the Government of Tanzania, Tanzania National Parks, Tanzania Commission for Science and Technology and Tanzania Wildlife Research Institute. Special thanks to the Center for Advanced Study in the Behavioral Sciences and the fellowship class of 2018–2019 for support and conversations that greatly improved this work.
© 2020 The Authors.
- death responses
- non-human primates