Cognitive underpinnings of competition in chacma baboons (Papio hamadryas ursinus).
Zusammenfassung der Projektergebnisse
Obvious capabilities unique to humans, including language, teaching, technology, generally boil down to our unprecedented degree of intelligence. Our brain has developed to an organ several magnitudes larger than those of other mammals and its evolution is stimulating compelling research. Despite research from a broad range of scientists, however, the selective pressures that shaped the evolution of our oversized brain remain a mystery. One widely discussed possibility is the social brain hypothesis. The social brain hypothesis assumes that the complexities of social living have driven the evolution of intelligence. Group living animals need to out-compete their fellow group members over food and mating partners. Those who monitor and remember their own and others' social bonds will do better in predicting alliances for and against themselves. With an increasing number of group members and types of relationships this cognitive task becomes exponentially more demanding. During the tenure of this project I investigated together with my collaborators the cognitive abilities employed by wild chacma baboons during intra-group competition and the quality of social bonds when coping with stressful social situations. I used play back experiments and hormonal analysis to understand the cognitive underpinnings of everyday competitive situations and coping mechanisms. Three play back experiments shed light on the baboons' knowledge of their social environment. First, together with my collaborators we were able to show that female baboons understand the social relationships among their fellow group members and that a close kin relative of an aggressor can substitute to reconcile with the victim on behalf of the aggressor. This recognition of others kin relationships allows baboons to reconcile conflicts although the victim does not allow the former aggressor into close proximity in the apparent fear of renewed aggression. A reanalysis of data that I had collected on wild chimpanzees confirmed this as a general pattern of primates. However in chimpanzees it was not the close kin relatives that substituted for the aggressor but the aggressor's close cooperation partner. Second, we proved that vocal support is an effective way to support a close bonding partner in baboons. Our playback experiment showed that vocal support of close kin is more effective than support by a non-kin in repelling the former opponent for a longer time. Third, my collaborators and I found that baboon males not only tracked transient relationships between others but used their knowledge to out-compete group members. Although other social animals seem likely to have a similar understanding of temporary relationships, this was the first time to show that animals track others short term relationships. Finally I investigated how social interactions help baboon females to cope with stressful events. During a period of social stability my collaborators and I looked into correlations between social parameters and glucocorticoid (GC) levels and found that not the amount of grooming given or received correlates with GC levels, but more with whom a female baboon is grooming. Females had lower GC levels during months of more focused grooming networks. This indicates that the quality of certain social bond is more important than the measured behaviour reflecting the relationship. We tested whether or not females would focus their grooming effort on a few good partners during a time a social instability where GC levels multiplied within a week. Indeed females who followed this strategy showed earlier reduce of GC levels than females who did not focus their grooming effort on less partners. Two main claims result from this project. First long-term and predictable social bonds have a highly adaptive value for social animals. Without such relationships life is much harder for social living mammals. Close bonding partners not only help out when being attacked, but they also help to buffer stressful situations. Second the results on cognitive abilities of baboons suggest a qualitative difference between primate and nonprimate cognition. Non-primate species have not yet been shown to monitor and recognise changes in transient relationships as well as to make causal inferences from the vocalisation and the affiliative relationships of the signaller although they have not even interacted with the signaller recently. Whether this is a qualitative difference between primates and non-primates or a lack of testing non-primate species remains yet open.
Projektbezogene Publikationen (Auswahl)
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Conflict management in chimpanzees and baboons: mechanisms and cognitive underpinnings. Living Links Colloquium, Yerkes Primate Research Centre & EMORY University, Atlanta, GO, USA. 4 October 2006
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(2007). Baboons eavesdrop to deduce mating opportunities. Animal Behaviour 73:885-890
Crockford, C., Wittig, R.M., Seyfarth, R.M. & Cheney, D.L.
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(2007). Kin-mediated reconciliation substitutes for direct reconciliation in female baboons. Proceedings of the Royal Society B 274:1109-1115
Wittig, R.M., Crockford, C., Wikberg, E., Seyfarth, R.M. & Cheney, D.L.
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(2007). Vocal support in Chacma baboons (Papio hamadryas ursinus). Behavioral Ecology and Sociobiology 61:899-909
Wittitg, R.M., Crockford, C., Seyfarth, R.M. & Cheney, D.L.
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Are primates the social geniuses? International Ethological Conference (Symposium: Social and cognitive convergence in vertebrates). 15 - 23 August 2007, Halifax, NS, Canada, 2007
Crockford, C., Wittig, R.M., Seyfarth, R.M. & Cheney, D.L.
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Function and effect of bystander initiated post-conflict affiliation in Taï chimpanzees. The mind of the chimpanzees. 22-25 March 2007, Chicago IL, USA, 2007
Wittig, R.M.
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Social Stressors and coping mechanisms in female baboons' everyday life. International Ethological Conference. 15 - 23 August 2007, Halifax, NS, Canada, 2007
Wittig, R.M., Crockford, C, Whitten, P.L., Seyfarth, R.M. & Cheney, D.L.
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Understanding others' relationships - social intelligence in monkeys and apes. VI. Göttinger Freilandtage. 11-14 December 2007, Göttingen, Germany, 2007
Wittig, R.M. & Crockford, C.
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(2008). Social Stressors and coping mechanisms in wild female baboons (Papio hamadryas ursinus). Hormones & Behavior 53:254-265
Crockford, C., Wittig, R.M., Whitten, P.L., Seyfarth, R.M. & Cheney, D.L.
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Baboons perceive grunts by approaching females as a signal of benign intent. International Primatological Society Meeting (Symposium: Meaning and function of primate vocalisations and gestures: monkeys and apes). 3-8 August 2008, Edinburgh, Scotland, UK, 2008
Wittig, R.M., Crockford, C., Seyfarth, R.M. & Cheney, D.L.
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Grooming helps to manage raised faecal glucocorticoid levels in female baboons (Papio hamadryas ursinus). International Primatological Society Meeting (Symposium: Hormones & Behaviour). 3-8 August 2008, Edinburgh, Scotland, UK, 2008
Crockford, C., Wittig, R.M., Whitten, P.L, Seyfarth, R.M. & Cheney, D.L.
