UC San Diego

The Social Intelligence Hypothesis proposes that the kind of complex cognition observed in humans and other species co-evolved with complex societies. Research focusing on this topic has been conducted mostly on primates, with a significant body of work conducted under the ‘Machiavellian Intelligence’ program. To further understand this relationship, there may be utility in looking beyond non-human primates to a species whose social complexity may be more similar to our own than any extant primate, with an updated methodological approach. Male bottlenose dolphins in Shark Bay, Western Australia, participate in up to three levels of alliance formation within a large society of resident dolphins. This nested structure of alliances may be the most complex outside of humans, but to date little is known about third-order alliances, or how alliance relationships may be mediated through social interaction. This study focused on the relationships among 24 male allies within this system over a six-year period of time to address two principal questions: (1) how are third-order alliances structured, what are their dynamics, and how do they respond to change? (2) how do the particular kinds of behavioral interactions that allies engage in relate to the observed structure and dynamics of the alliance network? I found that the alliance network demonstrated features of complex systems including local segregation and global integration, dynamic (non-linear) change, and the presence of social roles. The relationship between social complexity and social cognition was indicated by the range of interactions observed, as well as variability in when and with whom these interactions occurred. For example, second-order allies who frequently associated together engaged in higher rates of synchrony and affiliative contact. At a context hypothesized to have higher uncertainty (group joining events, or fusions), I found higher rates of social vocalizations, and higher rates affiliative interaction among third-order allies. This dissertation makes two kinds of contributions (a) toward the continued development of methodological practices for evaluating the proposed relationship between complex societies and complex cognition, and (b) toward further understanding of cetacean social organization, behavior, and cognition.