Lethal aggression in Pan is better explained by adaptive strategies than human impacts
Department of Anthropology, University of Minnesota, 395 Humphrey Center, 301 19th Avenue South, Minneapolis, MN, United States; Department of Ecology, Evolution and Behavior, University of Minnesota, 1987 Upper Buford Circle, St Paul, MN, United States; Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, Leipzig, Germany; Division of Neurobiology, Ludwig-Maximilians Universitaet Muenchen, Germany; Centre for Research and Conservation, Royal Zoological Society of Antwerp, Belgium; Primate Research Institute, Kyoto University, 41-2 Kanrin, Inuyama, Aichi, Japan; Department of Evolutionary Anthropology, Duke University, 104 Biological Sciences Building, Box 90383, Durham, NC, United States; School of Human Evolution and Social Change, Arizona State University, PO Box 872402, Tempe, AZ, United States; School of Psychology and Neuroscience, University of St. Andrews, Westburn Lane, St Andrews, Fife, United Kingdom; Wildlife Research Center, Kyoto University, 2-24 Tanaka-Sekiden-Cho, Sakyo, Kyoto, Japan; Division of Biological Anthropology, Department of Archaeology and Anthropology, University of Cambridge, Henry Wellcome Building, Fitzwilliam Street, Cambridge, United Kingdom; Zoology Department, Makerere University, P.O. Box 7062, Kampala, Uganda; Japan Monkey Center, 26 Kanrin, Inuyama, Aichi, Japan; Department of Anthropology, University of Michigan, 101 West Hall, 1085 S. University Avenue, Ann Arbor, MI, United States; Gombe Stream Research Centre, Jane Goodall Institute - Tanzania, P.O. Box 1182, Kigoma, Tanzania; Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, IL, United States; Department of Anthropology, MSC01-1040, University of New Mexico, Albuquerque, NM, United States; Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, Leipzig, Germany; Department of Anthropology, Iowa State University, 324 Curtiss, Ames, IA, United States; Department of Anthropology, Washington University in St. Louis, Campus Mailbox 1114, One Brookings Drive, St Louis, MO, United States; University of York, Department of Psychology, Heslington, York, United Kingdom; Department of Anthropology, University of Oregon, Eugene, OR, United States; Department of Anthropology, Yale University, 10 Sachem Street, New Haven, CT, United States; Université de Neuchâtel, Institut de Biologie, Rue Emile-Argand 11, Neuchâtel, Switzerland; Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA, United States
Observations of chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) provide valuable comparative data for understanding the significance of conspecific killing. Two kinds of hypothesis have been proposed. Lethal violence is sometimes concluded to be the result of adaptive strategies, such that killers ultimately gain fitness benefits by increasing their access to resources such as food or mates. Alternatively, it could be a non-adaptive result of human impacts, such as habitat change or food provisioning. To discriminate between these hypotheses we compiled information from 18 chimpanzee communities and 4 bonobo communities studied over five decades. Our data include 152 killings (n = 58 observed, 41 inferred, and 53 suspected killings) by chimpanzees in 15 communities and one suspected killing by bonobos. We found that males were the most frequent attackers (92% of participants) and victims (73%); most killings (66%) involved intercommunity attacks; and attackers greatly outnumbered their victims (median 8:1 ratio). Variation in killing rates was unrelated to measures of human impacts. Our results are compatible with previously proposed adaptive explanations for killing by chimpanzees, whereas the human impact hypothesis is not supported. ©2014 Macmillan Publishers Limited. All rights reserved.
adaptation; aggression; anthropogenic effect; conspecific; data acquisition; fitness; hominid; hunting; male; resource availability; species conservation; violence; adaptive behavior; aggression; Article; female; fighting; male; nonhuman; Pan paniscus; Pan troglodytes; population density; priority journal; victim; violence; Africa; animal; animal behavior; article; biological model; food; human; human activities; meta analysis; physiology; psychological aspect; sexual behavior; wild animal; Pan; Pan paniscus; Pan troglodytes; Africa; Aggression; Animals; Animals, Wild; Behavior, Animal; Female; Food; Human Activities; Humans; Male; Models, Biological; Pan paniscus; Pan troglodytes; Population Density; Sexual Behavior, Animal