Field study of wild animals is often asserted to have no role in discovering the cognitive capacities of the animal mind. In this lecture, I challenge that view, giving two examples where field data have revealed unsuspected cognitive capacities and allowed theoretical advance in understanding the evolutionary origins of human cognitive capacities. In the first, narrative records of deception of social companions were used as an ‘index’ of species' capacity for subtle social manipulation. This capacity was found to be widespread among primates, and to depend on neocortex volume, thus supporting theories that implicate social complexity in increasing primate intelligence. Intentional deception follows a quite different pattern, being rare and clumped in the great apes. The origins of the ability to understand others' behaviour, in terms of their intended purposes and the cause-and-effect involved in achieving them, forms the topic of my second example, great ape food processing. Wild apes regularly develop computationally complex organizations of behaviour, neatly adapted to solving food-acquisition problems and thus acquiring foods unreachable by sympatric competitor monkeys. Converging analyses of these manual techniques point to the underlying ability of ‘parsing behaviour’, giving apes (but perhaps no other animals) the ability to understand behaviour in a simple way, in which satisfying results stand for ‘goals’ and regular prior correlates stand for ‘causes’. In both cases, there are obvious implications for human cognitive evolution.

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Due to new impressive results in primates and even non-primates such as dogs, dolphins, and corvids, the question whether or not non-human animals possess elements of a ‘Theory of Mind’ (ToM) has recently gained momentum. Indeed, attempts have been put forward to test species with ecologically relevant tasks, leading to the development of new test paradigms, such as the competitive conspecific or ignorant helper, and to run controls for behaviour-based alternatives. I here argue for strengthening this integrative approach and present preliminary data from our model system, the common raven Corvus corax. Based on observations of tactical manoeuvres of wild and captive ravens during foraging, we have tested the ability of hand-raised birds to differentiate between conspecifics that do and do not know about cache locations because they have or have not been able to see the caches being made. In addition to this version of guesser-knower experiments, we have been investigating (i) if the birds' performance is affected by the manipulation of observable cues, (ii) how likely the performance can be achieved by attending to observable cues, (iii) how flexibly birds can apply their skills across contexts, (iv) how the skills develop during ontogeny and (v) how they are affected by experience. The potential implications of incorporating tests for behavioural cueing and learning as well as the issues of ontogeny and flexibility to studies on ToM are discussed.

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Many primate species live in groups with specific social structures. Much attention has been given to the social intelligence hypothesis, which claims that higher cognitive ability is required to survive in a complex than in a simple social world. Here, I describe four sets of studies that investigated social intelligence in captive chimpanzees, including tactical interactions in competition for food, the learning of tool use in a social situation, assisting of infants by mothers, and cooperative problem-solving behavior in an experimental situation. The results illustrate similarities and differences between humans and chimpanzees. Experimental studies using food as a reward tend to emphasize the competitive and selfish nature of chimpanzee behavior, whereas mother-offspring relationships in a non-food context may be a basis for the cooperative aspect of social intelligence.

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Cetaceans, including whales, dolphins, and porpoises, are mammals that live in aquatic environments far different from those of our terrestrial world. Recent studies have revealed that cetaceans have complex societies and cognitive abilities, comparable to those of “rational” terrestrial animals such as apes and humans. The positive correlation between relative brain sizes and group sizes in odontocetes apparently supports the social-brain hypothesis. In this paper, some recent cognitive studies, including those on tool use, object play, self-recognition, theory of mind (including false-belief task and joint attention), and complex social systems (which require higher cognitive ability), are reviewed to compare the cognitive abilities of cetaceans to those of other members of the “cognitive triangle,” including primates and corvids.

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