Studying the Evolution of Cooperation and Prosociality in Birds

The social brain hypothesis (Humphrey, 1976) poses that the intricacies of social life may have been a significant selection pressure for the evolution of mind. This evolution may act on competition between group members and strategies to outcompete others (Machiavellian intelligence hypothesis: Byrne & Whiten, 1988), or on cooperative tendencies between group-members that provide benefits that cannot be reached by a single individual (Vygotskian intelligence hypothesis: Moll & Tomasello, 2007). The latter hypothesis, however, creates an evolutionary conundrum, as cooperation is prone to free-riders, and with defection being an evolutionary stable system, the occurrence and complexity of cooperation in humans and other animals remains a puzzle. Several theoretical advances have been made to explain the evolution of cooperation nonetheless, with kin-selection (Hamilton, 1964) and reciprocal altruism (Trivers, 1971) being the most prominent ones. However, the proximate mechanisms that foster the strategies proposed in the Vygotskian intelligence hypothesis and the required cognition in nonhuman animals, remain a hotly debated topic (see Massen et al., 2019)