1 Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany, 2 Centre Suisse de Recherche Scientifique, Abidjan, Côte d'Ivoire
Abstract Top
In recent years, extended altruism towards unrelated group members has been proposed to be a unique characteristic of human societies. Support for this proposal seemingly came from experimental studies on captive chimpanzees that showed that individuals were limited in the ways they shared or cooperated with others. This dichotomy between humans and chimpanzees was proposed to indicate an important difference between the two species, and one study concluded that “chimpanzees are indifferent to the welfare of unrelated group members”. In strong contrast with these captive studies, consistent observations of potentially altruistic behaviors in different populations of wild chimpanzees have been reported in such different domains as food sharing, regular use of coalitions, cooperative hunting and border patrolling. This begs the question of what socio-ecological factors favor the evolution of altruism. Here we report 18 cases of adoption, a highly costly behavior, of orphaned youngsters by group members in Taï forest chimpanzees. Half of the adoptions were done by males and remarkably only one of these proved to be the father. Such adoptions by adults can last for years and thus imply extensive care towards the orphans. These observations reveal that, under the appropriate socio-ecologic conditions, chimpanzees do care for the welfare of other unrelated group members and that altruism is more extensive in wild populations than was suggested by captive studies.
Citation: Boesch C, Bolé C, Eckhardt N, Boesch H (2010) Altruism in Forest Chimpanzees: The Case of Adoption. PLoS ONE 5(1): e8901. doi:10.1371/journal.pone.0008901
Editor: Laurie Santos, Yale University, United States of America
Received: June 14, 2009; Accepted: January 4, 2010; Published: January 27, 2010
Copyright: © 2010 Boesch et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: For year-long faithful financial support, the authors are very grateful to the Swiss Science Foundation and the Max Planck Society. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: boesch@eva.mpg.de
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