Social Cognition in the New Caledonian Crow

Abstract

Co-operation in animal societies is not rare. How humans cooperate, however, appears to distinguish us from many non-human animals. Inequity aversion and reciprocal altruism have been shown to be critical to human cooperation. These abilities allow us to detect and respond to unequal outcomes and reciprocate to cooperative acts over time. In contrast, nonhuman animal cooperation is typically mediated by simpler cognitive mechanisms. New Caledonian (NC) crows are renowned for their impressive tool related abilities. Of all tool-using species, they are among the best at manufacturing and using a wide range of tools, and have demonstrated exceptional cognitive skill in physical problem-solving tasks. However, the social intelligence of NC crows has not yet been investigated. Therefore, it is unknown whether their impressive performance is underpinned by domain-specific or domain-general cognitive abilities. In this thesis I use a new stone-passing paradigm to investigate cooperation in NC crows. Although four out of five crows spontaneously solved the cooperative task, they failed to understand the role of their partner in the outcome. Instead, cooperation was maintained via individual reinforcement. Crows were not sensitive to inequity and did not show reciprocal altruism. Instead, data suggest that outcome was related to reward quantity. In contrast, when given a problem where they had to select between passing a functional or non-functional stone, three out of four crows preferentially selected the functional one. These results support the domain-specific position where cognitive abilities used to solve physical problems are separate to those required to solve social ones.