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Cantlon, J. F., & Brannon, E. M. (2007). How Much Does Number Matter to a Monkey (Macaca mulatta)? Journal of Experimental Psychology: Animal Behavior Processes, 33(1), 32–41.
Abstract: Although many animal species can represent numerical values, little is known about how salient number is relative to other object properties for nonhuman animals. In one hypothesis, researchers propose that animals represent number only as a last resort, when no other properties differentiate stimuli. An alternative hypothesis is that animals automatically, spontaneously, and routinely represent the numerical attributes of their environments. The authors compared the influence of number versus that of shape, color, and surface area on rhesus monkeys' (Macaca mulatta) decisions by testing them on a matching task with more than one correct answer: a numerical match and a nonnumerical (color, surface area, or shape) match. The authors also tested whether previous laboratory experience with numerical discrimination influenced a monkey's propensity to represent number. Contrary to the last-resort hypothesis, all monkeys based their decisions on numerical value when the numerical ratio was favorable.
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Chalmeau, R., & Gallo, A. (1995). Cooperation in primates: Critical analysis of behavioural criteria. Behav. Process., 35(1-3), 101–111.
Abstract: Concerning hunting in chimpanzees, cooperation has generally been attributed to the behaviour of two or more individuals acting together to achieve a common goal (Boesch and Boesch, 1989). The common goal is often considered as the concrete result of a common action by two or several individuals. Although this result could be used as a criterion for cooperation, it could also be an outcome due to chance. We suggest that the goal, viewed as a concrete benefit shared by the partners, is not a requisite of cooperation but rather a possible consequence of a common action largely submitted to social constraints. Individuals engaged in a cooperative task in order to solve a problem have to exchange information to adjust to each other's behaviour. However, evidence of communication between partners during simultaneous cooperation is rare. An experiment in which two chimpanzees each had to simultaneously pull a handle to get a fruit was performed. We analysed not only the concrete result of the partners' activity but also what the individuals took into account before pulling a handle. We tried to specify what the chimpanzees learned by means of a series of logical propositions which we were able to confront the experimental results.
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Kendrick, K. M. (1998). Intelligent perception. Appl. Anim. Behav. Sci., 57(3-4), 213–231.
Abstract: For an animal from any species to exhibit intelligent perception it must be capable of being consciously aware of what it perceives and capable of learning from this experience. Although many organisms, and for that matter machines, are capable of rapid adaptive learning in response to perception of environmental changes, such adaptations can occur without them being consciously aware either of external stimuli or their response to them. While behavioural and neurophysiological evidence suggests that, apart from ourselves, other higher primates must also be capable of such awareness, an important central question is whether such awareness is a characteristic of primate evolution or if it also occurs in sub-primate mammals as well. In this review I will examine our behavioural and neurophysiological evidence from visual and olfactory recognition studies in the sheep to support the argument that they are likely to be aware of and learn about both social and non-social objects and that they are therefore capable of intelligent perception. However, the impact of motivational changes on these perceptual processes suggests that they may be limited in terms of both prospection and retrospection and dealing with symbolic associations.
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Meunier, H., Leca, J. B., Deneubourg, J. L., & Petit, O. (2006). Group movement decisions in capuchin monkeys: the utility of an experimental study and a mathematical model to explore the relationship between individual and collective behaviours. Behaviour, 143, 1511–1527.
Abstract: In primate groups, collective movements are typically described as processes dependent on leadership mechanisms. However, in some species, decision-making includes negotiations and distributed leadership. These facts suggest that simple underlying processes may explain certain decision mechanisms during collective movements. To study such processes, we have designed experiments on white-faced capuchin monkeys (Cebus capucinus) during which we provoked collective movements involving a binary choice. These experiments enabled us to analyse the spatial decisions of individuals in the group. We found that the underlying process includes anonymous mimetism, which means that each individual may influence all members of the group. To support this result, we created a mathematical model issued from our experimental data. A totally anonymous model does not fit perfectly with our experimental distribution. A more individualised model, which takes into account the specific behaviour of social peripheral individuals, revealed the validity of the mimetism hypothesis. Even though white-faced capuchins have complex cognitive abilities, a coexistence of anonymous and social mechanisms appears to influence their choice of direction during collective movements. The present approach may offer vital insights into the relationships between individual behaviours and their emergent collective acts.
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Hoff, M. P., Powell, D. M., Lukas, K. E., & Maple, T. L. (1997). Individual and social behavior of lowland gorillas in outdoor exhibits compared with indoor holding areas. Appl. Anim. Behav. Sci., 54(4), 359–370.
Abstract: The behavior of nine lowland gorillas (Gorilla gorilla gorilla) living in three social groups at Zoo Atlanta was compared in an indoor holding area versus an outdoor exhibit. Focal animal data were collected for each animal during 15 min observation sessions, alternating between indoors and outdoors. A variety of solitary and social behaviors differed in the two conditions. All individual and social behaviors that showed a difference, except eating, occurred more indoors than outdoors. These included aggressive displays, reclining, self manipulation, and social examination of others. Additionally, the gorillas spent more time closer together in the indoor condition. A variety of other behaviors measured did not change between the two environments. There was a clear effect on behavior of the different housing conditions in which the gorillas were kept. It is suggested that the differences in aggressive behavior may be related to environmental complexity. It is further suggested that zoos should be aware that differences in behavior reported by caretaking staff, researchers and visitors may be a reflection of the differing environmental circumstances in which the animals are observed.
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Boyd, R., & Richerson, P. J. (1996). Why Culture is Common, but Cultural Evolution is Rare. Proc Br Acad, 88, 73–93.
Abstract: If culture is defined as variation acquired and maintained by social learning, then culture is common in nature. However, cumulative cultural evolution resulting in behaviors that no individual could invent on their own is limited to humans, song birds, and perhaps chimpanzees. Circumstantial evidence suggests that cumulative cultural evolution requires the capacity for observational learning. Here, we analyze two models the evolution of psychological capacities that allow cumulative cultural evolution. Both models suggest that the conditions which allow the evolution of such capacities when rare are much more stringent than the conditions which allow the maintenance of the capacities when common. This result follows from the fact that the assumed benefit of the capacities, cumulative cultural adaptation, cannot occur when the capacities are rare. These results suggest why such capacities may be rare in nature.
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Dunbar, R. I. M. (1998). The social brain hypothesis. Evol. Anthropol., 6(5), 178–190.
Abstract: Conventional wisdom over the past 160 years in the cognitive and neurosciences has assumed that brains evolved to process factual information about the world. Most attention has therefore been focused on such features as pattern recognition, color vision, and speech perception. By extension, it was assumed that brains evolved to deal with essentially ecological problem-solving tasks. © 1998 Wiley-Liss, Inc.
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Sawaguchi, T., & Kudo, H. (1990). Neocortical development and social structure in primates. Primates, 31(2), 283–289.
Abstract: Abstract  The relationships between the relative size of the neocortex and differences in social structures were examined in prosimians and anthropoids. The relative size of the neocortex (RSN) of a given congeneric group in each superfamily of primates was measured based on the allometric relationships between neocortical volume and brain weight for each superfamily, to control phylogenetic affinity and the effects of brain size. In prosimians, “troop-making” congeneric groups (N=3) revealed a significantly larger RSN than solitary groups (N=6), and there was a significant, positive correlation between RSN and troop size. In the case of anthropoids, polygynous/frugivorous groups (N=5) revealed a significantly larger RSN than monogynous/frugivorous groups (N=8). Furthermore, a significant, positive correlation between RSN and troop size was found for frugivorous congeneric groups of the Ceboidea. These results suggest that neocortical development is associated with differences in social structure among primates.
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Pérez-Barbería, F. J., Shultz, S., Dunbar, R. I. M., & Janis, C. (2007). Evidence For Coevolution Of Sociality And Relative Brain Size In Three Orders Of Mammals. Evolution, 61(12), 2811–2821.
Abstract: Abstract
As the brain is responsible for managing an individual's behavioral response to its environment, we should expect that large relative brain size is an evolutionary response to cognitively challenging behaviors. The “social brain hypothesis” argues that maintaining group cohesion is cognitively demanding as individuals living in groups need to be able to resolve conflicts that impact on their ability to meet resource requirements. If sociality does impose cognitive demands, we expect changes in relative brain size and sociality to be coupled over evolutionary time. In this study, we analyze data on sociality and relative brain size for 206 species of ungulates, carnivores, and primates and provide, for the first time, evidence that changes in sociality and relative brain size are closely correlated over evolutionary time for all three mammalian orders. This suggests a process of coevolution and provides support for the social brain theory. However, differences between taxonomic orders in the stability of the transition between small-brained/nonsocial and large-brained/social imply that, although sociality is cognitively demanding, sociality and relative brain size can become decoupled in some cases. Carnivores seem to have been especially prone to this.
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Köhler, W. (1921). Intelligenzprüfungen an Menschenaffen. Berlin: Springer.
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