Papers in the Biological Sciences


Date of this Version



Published in Animal Behaviour 65 (2003), pp. 479–487; doi:10.1006/anbe.2003.2101 Copyright © 2003; published by Elsevier Science Ltd. on behalf of The Association for the Study of Animal Behaviour. Used by permission.


The social complexity hypothesis asserts that animals living in large social groups should display enhanced cognitive abilities along predictable dimensions. To test this concept, we compared highly social pinyon jays, Gymnorhinus cyanocephalus, with relatively nonsocial western scrub-jays, Aphelocoma californica, on two complex cognitive tasks relevant to the ability to track and assess social relationships. Pinyon jays learned to track multiple dyadic relationships more rapidly and more accurately than scrub-jays and appeared to display a more robust and accurate mechanism of transitive inference. These results provide a clear demonstration of the association between social complexity and cognition in animals.