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  • Print publication year: 2018
  • Online publication date: July 2018

6 - Chimpanzees – Investigating Cognition in the Wild


Chimpanzees are one of our closest living relative. Like humans, they live in multi-male multi-female communities following fission-fusion dynamics. Their evolutionary and social closeness makes them a perfect target to investigate the evolutionary roots of human cognition. Although chimpanzee cognition has been studied extensively, most research has been conducted in captivity. Since cognition is supposed to be shaped by the ecological and social environment, here we mainly review cognitive studies on wild chimpanzees. Chimpanzees in the wild use a wide range of social and physical cognition to gain knowledge about others, cooperate with conspecifics, and use their spatial knowledge and knowledge about tool properties. We then review different methods to investigate cognitive abilities in wild chimpanzees, in order to introduce readers to the different possible experimental set-ups. We finally discuss the advantages and problems of play-back experiments, object presentations and combinations of the two approaches. We want to provide readers with the knowledge that the investigation of many ecological relevant question in cognition needs a natural setup, allowing chimpanzees to draw from experience shaped by natural pressure.
Balda, R. P., Kamil, A. C., and Bednekoff, P. A. (1996). Predicting cognitive capacity from natural history: examples from four species of corvids. Current Ornithology, 13, 3366.
Bird, C. D., and Emery, N. J. (2009). Insightful problem solving and creative tool modification by captive nontool-using rooks. Proceedings of the National Academy of Sciences, 106, 1037010375.
Emery, N. J., and Clayton, N. S. (2004). The mentality of crows: convergent evolution of intelligence in corvids and apes. Science, 306, 19031907.
Greggor, A. L., McIvor, G. E., Clayton, N. S., and Thornton, A. (2016). Contagious risk taking: social information and context influence wild jackdaws’ responses to novelty and risk. Scientific Reports, 6, 27764.
Hunt, G. R. (1996). Manufacture and use of hook-tools by New Caledonian crows. Nature, 379, 249251.
Hunt, G. R. (2016). Social and spatial reintegration success of New Caledonian crows (Corvus moneduloides) released after aviary confinement. Wilson Journal of Ornithology, 128, 168173.
Kabadayi, C., and Osvath, M. (2017). Ravens parallel great apes in flexible planning for tool-use and bartering. Science, 357, 202204.
Klump, B. C., Sugasawa, S., St Clair, J. J. H., and Rutz, C. (2015). Hook tool manufacture in New Caledonian crows: behavioural variation and the influence of raw materials. BMC Biology, 13, 97.
Loretto, M.-C., Schuster, R., Itty, C., Marchand, P., Genero, F., and Bugnyar, T. (2017). Fission–fusion dynamics over large distances in raven non-breeders. Scientific Reports, 7, 380.
Massen, J. J. M., Pašukonis, A., Schmidt, J., and Bugnyar, T. (2014). Ravens notice dominance reversals among conspecifics within and outside their social group. Nature Communications, 5, 3679.
Raby, C. R., Alexis, D. M., Dickinson, A., and Clayton, N. S. (2007). Planning for the future by western scrub-jays. Nature, 445, 919921.
Rutz, C., Bluff, L. A., Weir, A. A. S., and Kacelnik, A. (2007). Video cameras on wild birds. Science, 318, 765.
Rutz, C., Klump, B. C., Komarczyk, L., et al. (2016a). Discovery of species-wide tool use in the Hawaiian crow. Nature, 537, 403407.
Rutz, C., Sugasawa, S., van der Wal, J. E. M., Klump, B. C., and St Clair, J. J. H. (2016b). Tool bending in New Caledonian crows. Royal Society Open Science, 3, 160439.
St Clair, J. J. H., Burns, Z. T., Bettaney, E., et al. (2015). Experimental resource pulses influence social-network dynamics and the potential for information flow in tool-using crows. Nature Communications, 6, 7197.
Swift, K. N., and Marzluff, J. M. (2015). Wild American crows gather around their dead to learn about danger. Animal Behaviour, 109, 187197.
Taylor, A. H., Hunt, G. R., Holzhaider, J. C., and Gray, R. D. (2007). Spontaneous metatool use by New Caledonian crows. Current Biology, 17, 15041507.
Wascher, C. A. F., Hillemann, F., Canestrari, D., and Baglione, V. (2015). Carrion crows learn to discriminate between calls of reliable and unreliable conspecifics. Animal Cognition, 18, 11811185.
Fischer, J. (2017). Monkeytalk: inside the worlds and minds of primates. Chicago, IL: University of Chicago Press.
Arnold, K., and Whiten, A. (2001). Post-conflict behaviour of wild chimpanzees (Pan troglodytes schweinfurthii) in the Budongo forest, Uganda. Behaviour, 138, 649690.
Ban, S. D., Boesch, C., and Janmaat, K. R. L. (2014). Taï chimpanzees anticipate revisiting high-valued fruit trees from further distances. Animal Cognition, 17, 13531364.
Bates, D., Kliegl, R., Vasishth, S., and Baayen, H. (2015). Parsimonious mixed models. ArXiv:1506.04967 [Stat]. Retrieved from
Boesch, C. (1991). Teaching among wild chimpanzees. Animal Behaviour, 41, 530532.
Boesch, C. (1996). Hunting strategies of Gombe and Tai chimpanzees. In Chimpanzee cultures (pp. 7791). Cambridge, MA: Harvard University Press.
Boesch, C. (2002). Cooperative hunting roles among Taï chimpanzees. Human Nature, 13, 2746.
Boesch, C. (2007). What makes us human (Homo sapiens): the challenge of cognitive cross-species comparison. Journal of Comparative Psychology, 121, 227240.
Boesch, C., and Boesch, H. (1982). Optimisation of nut-cracking with natural hammers by wild chimpanzees. Behaviour, 83, 265286.
Boesch, C., and Boesch, H. (1989). Hunting behavior of wild chimpanzees in the Taï National Park. American Journal of Physical Anthropology, 78, 547573.
Boesch, C., and Boesch-Achermann, H. (2000). The chimpanzees of the Taï forest: behavioural ecology and evolution. Oxford: Oxford University Press.
Boesch, C., Kohou, G., Néné, H., and Vigilant, L. (2006). Male competition and paternity in wild chimpanzees of the Taï forest. American Journal of Physical Anthropology, 130, 103115.
Boesch, C., Crockford, C., Herbinger, I., Wittig, R., Moebius, Y., and Normand, E. (2008). Intergroup conflicts among chimpanzees in Taï National Park: lethal violence and the female perspective. American Journal of Primatology, 70, 519532.
Boesch, C., Head, J., and Robbins, M. M. (2009). Complex tool sets for honey extraction among chimpanzees in Loango National Park, Gabon. Journal of Human Evolution, 56, 560569.
Boesch, C., Bolé, C., Eckhardt, N., and Boesch, H. (2010). Altruism in forest chimpanzees: the case of adoption. PLoS ONE, 5(1), e8901.
Brüne, M., and Brüne-Cohrs, U. (2006). Theory of mind – evolution, ontogeny, brain mechanisms and psychopathology. Neuroscience and Biobehavioral Reviews, 30, 437455.
Byrne, R., and Whiten, A. (1989). Machiavellian intelligence: social expertise and the evolution of intellect in monkeys, apes, and humans. Oxford: Oxford University Press.
Call, J. (2009). Contrasting the social cognition of humans and nonhuman apes: the shared intentionality hypothesis. Topics in Cognitive Science, 1, 368379.
Campbell, G., Kuehl, H., Diarrassouba, A., N’Goran, P. K., and Boesch, C. (2011). Long-term research sites as refugia for threatened and over-harvested species. Biology Letters, 7, 723726.
Carter, C. S., Harris, J., and Porges, S. W. (2011). Neural and evolutionary perspectives on empathy. In The social neuroscience of empathy (pp. 169182). Cambridge, MA: MIT Press.
Cheney, D. L., and Seyfarth, R. M. (2008). Baboon metaphysics: the evolution of a social mind. Chicago, IL: University of Chicago Press.
Christel, M. (1993). Grasping techniques and hand preferences in Hominoidea. In Hands of primates (pp. 91108). Vienna: Springer.
Coolidge, H. J., and Shea, B. T. (1982). External body dimensions of Pan paniscus and Pan troglodytes chimpanzees. Primates, 23, 245251.
Crockford, C., and Boesch, C. (2003). Context-specific calls in wild chimpanzees, Pan troglodytes verus: analysis of barks. Animal Behaviour, 66, 115125.
Crockford, C., and Boesch, C. (2005). Call combinations in wild chimpanzees. Behaviour, 142, 397421.
Crockford, C., Herbinger, I., Vigilant, L., and Boesch, C. (2004). Wild chimpanzees produce group-specific calls: a case for vocal learning? Ethology, 110, 221243.
Crockford, C., Wittig, R. M., Seyfarth, R. M., and Cheney, D. L. (2007). Baboons eavesdrop to deduce mating opportunities. Animal Behaviour, 73, 885890.
Crockford, C., Wittig, R. M., Mundry, R., and Zuberbühler, K. (2012). Wild chimpanzees inform ignorant group members of danger. Current Biology, 22, 142146.
Crockford, C., Wittig, R. M., Langergraber, K., Ziegler, T. E., Zuberbühler, K., and Deschner, T. (2013). Urinary oxytocin and social bonding in related and unrelated wild chimpanzees. Proceedings of the Royal Society of London B: Biological Sciences, 280, 20122765.
Crockford, C., Wittig, R. M., and Zuberbühler, K. (2015). An intentional vocalization draws others’ attention: a playback experiment with wild chimpanzees. Animal Cognition, 18, 581591.
Crockford, C., Wittig, R. M., and Zuberbuehler, K. (2017). Vocalizing in chimpanzees is influenced by social cognitive processes. Science Advances, 3(11), e1701742.
Cronin, K. A., Pieper, B., van Leeuwen, E. J., Crockford, C., and Haun, D. B. (2015). Cooperating to compete: evaluating behavioral coordination in response to simulated territorial intrusion in chimpanzees (Pan troglodytes). American Journal of Primatology, 77(S1), 64.
Duffy, K. G., Wrangham, R. W., and Silk, J. B. (2007). Male chimpanzees exchange political support for mating opportunities. Current Biology, 17, 586587.
Estienne, V., Stephens, C., and Boesch, C. (2017). Extraction of honey from underground bee nests by central African chimpanzees (Pan troglodytes troglodytes) in Loango National Park, Gabon: techniques and individual differences. American Journal of Primatology, 79, 101109.
Fischer, J., Noser, R., and Hammerschmidt, K. (2013). Bioacoustic field research: a primer to acoustic analyses and playback experiments with primates. American Journal of Primatology, 75, 643663.
Fraser, O. N., Koski, S. E., Wittig, R. M., and Aureli, F. (2009). Why are bystanders friendly to recipients of aggression? Communicative and Integrative Biology, 2, 285291.
Gilby, I. C. (2006). Meat sharing among the Gombe chimpanzees: harassment and reciprocal exchange. Animal Behaviour, 71, 953963.
Gilby, I. C., and Connor, R. C. (2010). The role of intelligence in group hunting: are chimpanzees different from other social predators? In The mind of the chimpanzee: ecological and experimental perspectives (pp. 220232). Chicago, IL: University of Chicago Press.
Gilby, I. C., Thompson, M. E., Ruane, J. D., and Wrangham, R. (2010). No evidence of short-term exchange of meat for sex among chimpanzees. Journal of Human Evolution, 59, 4453.
Gomes, C. M., and Boesch, C. (2009). Wild chimpanzees exchange meat for sex on a long-term basis. PLoS ONE, 4(4), e5116.
Gomes, C. M., Mundry, R., and Boesch, C. (2009). Long-term reciprocation of grooming in wild West African chimpanzees. Proceedings of the Royal Society of London B: Biological Sciences, 276, 699706.
Goodall, J. (1986). The chimpanzees of Gombe: patterns of behavior. Cambridge, MA: Harvard University Press.
Gruber, T., Muller, M. N., Strimling, P., Wrangham, R., and Zuberbühler, K. (2009). Wild chimpanzees rely on cultural knowledge to solve an experimental honey acquisition task. Current Biology, 19, 18061810.
Grützmacher, K., Keil, V., Leinert, V., et al. (2017). Human quarantine: toward reducing infectious pressure on chimpanzees at the Taï Chimpanzee Project, Côte d’Ivoire. American Journal of Primatology, 80, e22619.
Hare, B., Call, J., and Tomasello, M. (2001). Do chimpanzees know what conspecifics know? Animal Behaviour, 61, 139151.
Herrmann, E., Call, J., Hernàndez-Lloreda, M. V., Hare, B., and Tomasello, M. (2007). Humans have evolved specialized skills of social cognition: the cultural intelligence hypothesis. Science, 317, 13601366.
Herrmann, E., Hernández-Lloreda, M. V., Call, J., Hare, B., and Tomasello, M. (2010). The structure of individual differences in the cognitive abilities of children and chimpanzees. Psychological Science, 21, 102110.
Heymann, E. W. (2006). The neglected sense – olfaction in primate behavior, ecology, and evolution. American Journal of Primatology, 68, 519524.
Hobaiter, C., Schel, A. M., Langergraber, K., and Zuberbühler, K. (2014). ‘Adoption’ by maternal siblings in wild chimpanzees. PLoS ONE, 9(8), e103777.
Hockings, K. J., Humle, T., Anderson, J. R., et al. (2007). Chimpanzees share forbidden fruit. PLoS ONE, 2(9), e886.
Horner, V., and Whiten, A. (2005). Causal knowledge and imitation/emulation switching in chimpanzees (Pan troglodytes) and children (Homo sapiens). Animal Cognition, 8, 164181.
Humle, T., and Matsuzawa, T. (2002). Ant-dipping among the chimpanzees of Bossou, Guinea, and some comparisons with other sites. American Journal of Primatology, 58, 133148.
Inoue, S., and Matsuzawa, T. (2007). Working memory of numerals in chimpanzees. Current Biology, 17, 10041005.
Inoue-Nakamura, N., and Matsuzawa, T. (1997). Development of stone tool use by wild chimpanzees (Pan troglodytes). Journal of Comparative Psychology, 111, 159173.
Janmaat, K. R. L., Ban, S. D., and Boesch, C. (2013). Taï chimpanzees use botanical skills to discover fruit: what we can learn from their mistakes. Animal Cognition, 16, 851860.
Janmaat, K. R. L., Polansky, L., Ban, S. D., and Boesch, C. (2014). Wild chimpanzees plan their breakfast time, type, and location. Proceedings of the National Academy of Sciences, 111, 1634316348.
Kahlenberg, S. M., Thompson, M. E., Muller, M. N., and Wrangham, R. W. (2008a). Immigration costs for female chimpanzees and male protection as an immigrant counterstrategy to intrasexual aggression. Animal Behaviour, 76, 14971509.
Kahlenberg, S. M., Thompson, M. E., and Wrangham, R. W. (2008b). Female competition over core areas in Pan troglodytes schweinfurthii, Kibale National Park, Uganda. International Journal of Primatology, 29, 931.
Köhler, W. (2013). Intelligenzprüfungen an Menschenaffen: mit einem Anhang zur Psychologie des Schimpansen (Vol. 134). Berlin: Springer.
Kojima, S. (1990). Comparison of auditory functions in the chimpanzee and human. Folia Primatologica, 55, 6272.
Köndgen, S., Kühl, H., N’Goran, P. K., et al. (2008). Pandemic human viruses cause decline of endangered great apes. Current Biology, 18, 260264.
Krupenye, C., Kano, F., Hirata, S., Call, J., and Tomasello, M. (2016). Great apes anticipate that other individuals will act according to false beliefs. Science, 354, 110114.
Kühl, H. S., Kalan, A. K., Arandjelovic, M., et al. (2016). Chimpanzee accumulative stone throwing. Scientific Reports, 6, 22219.
Kutsukake, N., and Castles, D. L. (2004). Reconciliation and post-conflict third-party affiliation among wild chimpanzees in the Mahale Mountains, Tanzania. Primates, 45, 157165.
Langergraber, K. E., Mitani, J. C., and Vigilant, L. (2007). The limited impact of kinship on cooperation in wild chimpanzees. Proceedings of the National Academy of Sciences, 104, 77867790.
Langergraber, K. E., Boesch, C., Inoue, E., et al. (2010). Genetic and ‘cultural’ similarity in wild chimpanzees. Proceedings of the Royal Society of London B: Biological Sciences, 278, 20101112.
Langergraber, K. E., Prüfer, K., Rowney, C., et al. (2012). Generation times in wild chimpanzees and gorillas suggest earlier divergence times in great ape and human evolution. Proceedings of the National Academy of Sciences, 109, 1571615721.
Lonsdorf, E. V. (2006). What is the role of mothers in the acquisition of termite-fishing behaviors in wild chimpanzees (Pan troglodytes schweinfurthii)? Animal Cognition, 9, 3646.
Luncz, L. V., Mundry, R., and Boesch, C. (2012). Evidence for cultural differences between neighboring chimpanzee communities. Current Biology, 22, 922926.
Luncz, L. V., Wittig, R. M., and Boesch, C. (2015). Primate archaeology reveals cultural transmission in wild chimpanzees (Pan troglodytes verus). Philosophical Transactions of the Royal Society B: Biological Sciences, 370, 20140348.
Martin-Ordas, G., Haun, D., Colmenares, F., and Call, J. (2010). Keeping track of time: evidence for episodic-like memory in great apes. Animal Cognition, 13, 331340.
Matsumoto-Oda, A., Kutsukake, N., Hosaka, K., and Matsusaka, T. (2007). Sniffing behaviors in Mahale chimpanzees. Primates, 48, 8185.
Matsuno, T., Kawai, N., and Matsuzawa, T. (2004). Color classification by chimpanzees (Pan troglodytes) in a matching-to-sample task. Behavioural Brain Research, 148, 157165.
Matsuzawa, T., Biro, D., Humle, T., Inoue-Nakamura, N., Tonooka, R., and Yamakoshi, G. (2008). Emergence of culture in wild chimpanzees: education by master-apprenticeship. In Primate origins of human cognition and behavior (pp. 557574). Japan: Springer.
Mennill, D. J., Ratcliffe, L. M., and Boag, P. T. (2002). Female eavesdropping on male song contests in songbirds. Science, 296, 873.
Menzel, C. R. (1999). Unprompted recall and reporting of hidden objects by a chimpanzee (Pan troglodytes) after extended delays. Journal of Comparative Psychology, 113, 426434.
Mielke, A., Samuni, L., Preis, A., Gogarten, J. F., Crockford, C., and Wittig, R. M. (2017). Bystanders intervene to impede grooming in Western chimpanzees and sooty mangabeys. Royal Society Open Science, 4(11), 171296.
Mitani, J. C., and Watts, D. P. (2001). Why do chimpanzees hunt and share meat? Animal Behaviour, 61, 915924.
Mitani, J. C., Merriwether, D. A., and Zhang, C. (2000). Male affiliation, cooperation and kinship in wild chimpanzees. Animal Behaviour, 59, 885893.
Mitani, J. C., Watts, D. P., and Amsler, S. J. (2010). Lethal intergroup aggression leads to territorial expansion in wild chimpanzees. Current Biology, 20, 507508.
Mulcahy, N. J., and Call, J. (2006). Apes save tools for future use. Science, 312, 10381040.
Mundry, R. (2017). From nonparametric tests to mixed models: a brief overview of statistical tools frequently used in comparative psychology. In APA Handbook of comparative psychology, Vol. 1 (pp. 157177). Philadelphia, PA: American Psychological Association.
Newton-Fisher, N. E., and Lee, P. C. (2011). Grooming reciprocity in wild male chimpanzees. Animal Behaviour, 81, 439446.
Nishida, T. (1968). The social group of wild chimpanzees in the Mahali Mountains. Primates, 9, 167224.
Nishida, T., Hasegawa, T., Hayaki, H., Takahata, Y., and Uehara, S. (1992). Meat-sharing as a coalitionary strategy by an alpha male chimpanzee. In Topics in primatology (pp. 159174). Tokyo: University of Tokyo Press.
Normand, E., and Boesch, C. (2009). Sophisticated Euclidean maps in forest chimpanzees. Animal Behaviour, 77, 11951201.
Normand, E., Ban, S. D., and Boesch, C. (2009). Forest chimpanzees (Pan troglodytes verus) remember the location of numerous fruit trees. Animal Cognition, 12, 797807.
Povinelli, D. J., and Vonk, J. (2003). Chimpanzee minds: suspiciously human? Trends in Cognitive Sciences, 7, 157160.
Premack, D., and Woodruff, G. (1978). Does the chimpanzee have a theory of mind? Behavioral and Brain Sciences, 1, 515526.
Pruetz, J. D., and Bertolani, P. (2007). Savanna chimpanzees, Pan troglodytes verus, hunt with tools. Current Biology, 17, 412417.
Radford, A. N., Majolo, B., and Aureli, F. (2016). Within-group behavioural consequences of between-group conflict: a prospective review. Proceedings of the Royal Society of London B: Biological Sciences, 283, 1843.
Ramsey, G., Bastien, M. L., and van Schaik, C. (2007). Animal innovation defined and operationalized. Behavioural and Brain Sciences, 30, 393437.
Rilling, J. K., and Young, L. J. (2014). The biology of mammalian parenting and its effect on offspring social development. Science, 345, 771776.
Samuni, L., Preis, A., Mundry, R., Deschner, T., Crockford, C., and Wittig, R. M. (2017). Oxytocin reactivity during intergroup conflict in wild chimpanzees. Proceedings of the National Academy of Sciences, 114, 268273.
Sanz, C. M., and Morgan, D. B. (2007). Chimpanzee tool technology in the Goualougo Triangle, Republic of Congo. Journal of Human Evolution, 52, 420433.
Schel, A. M., Machanda, Z., Townsend, S. W., Zuberbühler, K., and Slocombe, K. E. (2013a). Chimpanzee food calls are directed at specific individuals. Animal Behaviour, 86, 955965.
Schel, A. M., Townsend, S. W., Machanda, Z., Zuberbuehler, K., and Slocombe, K. E. (2013b). Chimpanzee alarm call production meets key criteria for intentionality. PLoS ONE, 8(10), e76674.
Schino, G., and Aureli, F. (2010). Primate reciprocity and its cognitive requirements. Evolutionary Anthropology, 19, 130135.
Seyfarth, R. M., and Cheney, D. L. (2012). The evolutionary origins of friendship. Annual Review of Psychology, 63, 153177.
Seyfarth, R. M., and Cheney, D. L. (2013). Affiliation, empathy, and the origins of theory of mind. Proceedings of the National Academy of Sciences, 110, 1034910356.
Sirianni, G., Mundry, R., and Boesch, C. (2015a). When to choose which tool: multidimensional and conditional selection of nut-cracking hammers in wild chimpanzees. Animal Behaviour, 100, 152165.
Sirianni, G., Wittig, R. M., and Boesch, C. (2015b). Do chimpanzees anticipate an object’s weight? A field experiment on the kinematics of hammer-lifting movements in the nut-cracking Tai chimpanzees. Folia Primatologica, 86, 360361.
Slocombe, K. E., and Zuberbühler, K. (2007). Chimpanzees modify recruitment screams as a function of audience composition. Proceedings of the National Academy of Sciences, 104, 1722817233.
Slocombe, K. E., and Zuberbühler, K. (2010). Vocal communication in chimpanzees. In The mind of the chimpanzee: ecological and experimental perspectives (pp. 192207). Chicago, IL: Chicago University Press.
Slocombe, K. E., Kaller, T., Turman, L., et al. (2010). Production of food-associated calls in wild male chimpanzees is dependent on the composition of the audience. Behavioral Ecology and Sociobiology, 64, 19591966.
Surbeck, M., Boesch, C., Girard-Buttoz, C., Crockford, C., Hohmann, G., and Wittig, R. M. (2017a). Comparison of male conflict behavior in chimpanzees (Pan troglodytes) and bonobos (Pan paniscus), with specific regard to coalition and post-conflict behavior. American Journal of Primatology, 79, e22641.
Surbeck, M., Girard-Buttoz, C., Boesch, C., et al. (2017b). Sex-specific association patterns in bonobos and chimpanzees reflect species differences in cooperation. Royal Society Open Science, 4, 161081.
Tomasello, M. (2009a). The cultural origins of human cognition. Cambridge, MA: Harvard University Press.
Tomasello, M. (2009b). Why we cooperate. Cambridge, MA: MIT Press.
Tomasello, M., and Call, J. (1997). Primate cognition. Oxford: Oxford University Press.
Uehara, S., and Nishida, T. (1987). Body weights of wild chimpanzees (Pan troglodytes schweinfurthii) of the Mahale Mountains National Park, Tanzania. American Journal of Physical Anthropology, 72, 315321.
van Lawick-Goodall, J. (1968). The behaviour of free-living chimpanzees in the Gombe Stream Reserve. Animal Behaviour Monographs, 1, 161-IN12.
Watts, D. P. (2000). Grooming between male chimpanzees at Ngogo, Kibale National Park. I. Partner number and diversity and grooming reciprocity. International Journal of Primatology, 21, 189210.
Watts, D. P., and Mitani, J. C. (2001). Boundary patrols and intergroup encounters in wild chimpanzees. Behaviour, 138, 299327.
Whiten, A., Goodall, J., McGrew, W. C., et al. (1999). Cultures in chimpanzees. Nature, 399, 682685.
Wilson, M. L., and Wrangham, R. W. (2003). Intergroup relations in chimpanzees. Annual Review of Anthropology, 32, 363392.
Wilson, M. L., Kahlenberg, S. M., Wells, M., and Wrangham, R. W. (2012). Ecological and social factors affect the occurrence and outcomes of intergroup encounters in chimpanzees. Animal Behaviour, 83, 277291.
Wilson, M. L., Boesch, C., Fruth, B., et al. (2014). Lethal aggression in Pan is better explained by adaptive strategies than human impacts. Nature, 513, 414417.
Wittig, R. M., and Boesch, C. (2003a). Food competition and linear dominance hierarchy among female chimpanzees of the Taï National Park. International Journal of Primatology, 24, 847867.
Wittig, R. M., and Boesch, C. (2003b). The choice of post-conflict interactions in wild chimpanzees (Pan troglodytes). Behaviour, 140, 15271559.
Wittig, R. M., and Boesch, C. (2010). Receiving post-conflict affiliation from the enemy’s friend reconciles former opponents. PLoS ONE, 5(11), e13995.
Wittig, R. M., Crockford, C., Seyfarth, R. M., and Cheney, D. L. (2007a). Vocal alliances in Chacma baboons (Papio hamadryas ursinus). Behavioral Ecology and Sociobiology, 61, 899909.
Wittig, R. M., Crockford, C., Wikberg, E., Seyfarth, R. M., and Cheney, D. L. (2007b). Kin-mediated reconciliation substitutes for direct reconciliation in female baboons. Proceedings of the Royal Society of London B: Biological Sciences, 274, 11091115.
Wittig, R. M., Crockford, C., Deschner, T., Langergraber, K. E., Ziegler, T. E., and Zuberbühler, K. (2014a). Food sharing is linked to urinary oxytocin levels and bonding in related and unrelated wild chimpanzees. Proceedings of the Royal Society of London B: Biological Sciences, 281, 20133096.
Wittig, R. M., Crockford, C., Langergraber, K. E., and Zuberbühler, K. (2014b). Triadic social interactions operate across time: a field experiment with wild chimpanzees. Proceedings of the Royal Society of London B: Biological Sciences, 281, 20133155.
Wittig, R. M., Crockford, C., Weltring, A., Langergraber, K. E., Deschner, T., and Zuberbühler, K. (2016). Social support reduces stress hormone levels in wild chimpanzees across stressful events and everyday affiliations. Nature Communications, 7, 13361.
Wroblewski, E. E. (2008). An unusual incident of adoption in a wild chimpanzee (Pan troglodytes) population at Gombe National Park. American Journal of Primatology, 70, 995998.
Wroblewski, E. E., Murray, C. M., Keele, B. F., Schumacher-Stankey, J. C., Hahn, B. H., and Pusey, A. E. (2009). Male dominance rank and reproductive success in chimpanzees, Pan troglodytes schweinfurthii. Animal Behaviour, 77, 873885.
Zuberbühler, K., and Byrne, R. W. (2006). Social cognition. Current Biology, 16, 786790.
Zuberbühler, K., and Wittig, R. M. (2011). Field experiments with nonhuman primates: a tutorial. In Field and laboratory methods in primatology: a practical guide (pp. 207224). Cambridge: Cambridge University Press.