Dunbar, R. I. M. (1974). Observations on the ecology and social organization of the green monkey,Cercopithecus sabaeus, in Senegal. Primates, 15(4), 341–350.
Abstract: The green monkey,Cercopithecus sabaeus, has not been studied in its natural habitat in West Africa. This paper reports observations made during a 3-month study in Senegal. Green monkeys live in multimale groups averaging some 12 individuals. Information is given on home range size, use of habitat, daily activity patterns, diet and birth seasonality. Social organization is discussed and data are given on the relationships between age-sex classes, aggression and leadership. Inter-group relations are discussed and it is suggested that groups defend their ranges as territories. The ecology and social organization of green monkeys is compared with that of populations ofC. aethiops studied in East Africa and they are found to be similar.
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O'Connell, S., & Dunbar, R. I. M. (2005). The perception of causality in chimpanzees (Pan spp.). Anim. Cogn., 8(1), 60–66.
Abstract: Chimpanzees (Pan spp.) were tested on a habituation/dishabituation paradigm that was originally developed to test for comprehension of causality in very young human infants. Three versions of the test were used: a food item being moved by a hand, a human pushing another human off a chair to obtain a food item, and a film clip of natural chimpanzee behaviour (capturing and eating a monkey). Chimpanzees exhibited similar results to those obtained with human infants, with significantly elevated levels of looking on the dishabituation trials. Since the level of response was significantly greater on natural/unnatural sequences than on unnatural/natural sequences, we conclude that the chimpanzees were not responding just to novelty but rather to events that infringed their sense of natural causation.
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Dunbar, R. I. M. (2007). Male and female brain evolution is subject to contrasting selection pressures in primates. BMC Biol, 5, 21.
Abstract: The claim that differences in brain size across primate species has mainly been driven by the demands of sociality (the “social brain” hypothesis) is now widely accepted. Some of the evidence to support this comes from the fact that species that live in large social groups have larger brains, and in particular larger neocortices. Lindenfors and colleagues (BMC Biology 5:20) add significantly to our appreciation of this process by showing that there are striking differences between the two sexes in the social mechanisms and brain units involved. Female sociality (which is more affiliative) is related most closely to neocortex volume, but male sociality (which is more competitive and combative) is more closely related to subcortical units (notably those associated with emotional responses). Thus different brain units have responded to different selection pressures.
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