Date of Award

Spring 5-15-2023

Author's School

Graduate School of Arts and Sciences

Author's Department


Degree Name

Doctor of Philosophy (PhD)

Degree Type



In human societies, individuals who hold social roles are recognized by others as possessing context- or task-specific proficiencies and skills. The social roles that are arguably unique to our societies confer many functional benefits, however multidisciplinary interests in the topic lack an evolutionary framework that allows for the comparative elements and emergence of social roles to be investigated. In this research, we put forth four elements of social roles in societies that can be compared across species: those that are context-specific, expressed over time, offer functional advantages, and individuals who hold social roles are recognized by conspecifics as possessing characteristics. To simultaneously assess comparative elements of the cognitive mechanisms that support social roles, we identify behavioral indicators of shared intentionality. With this framework, we examined aspects of social roles in the fission-fusion societies and social interactions of chimpanzees across multiple sites and settings. In the Goualougo Triangle (Republic of Congo) we examined patterns of party co-attendance and identified context-specific specializations that are consistently expressed by the same individuals, stable in their expression over many years, and functionally beneficial in expediting the possible transmission of information. Across nine chimpanzee social groups at Save the Chimps sanctuary (Florida, USA) and the Saint Louis Zoo (Missouri, USA) we found that individuals recognized the role-specific actions of skilled mediators of reparative conflict interventions. Additionally, we observed the chimpanzees to readily employ the cognitive mechanisms that support social roles via constructing joint commitments in mutual grooming and shared social attention in coalitionary aggression. Our results provide some of the first systematic evidence of social roles and shared intentions in chimpanzees. These results place new emphasis on the social pressures that likely shaped the emergence of social roles and shared intentions. Additionally, the enhanced understanding of chimpanzee social roles that we provide expands the known range of behavioral diversity of this species. It is critical to consider social complexity as an integral part of chimpanzee behavioral diversity to best inform initiatives that safeguard wild chimpanzees and promote the wellbeing of captive populations.


English (en)

Chair and Committee

Crickette Sanz

Committee Members

Richard Smith, Krista Milich, Emily Wroblewski, David Morgan,

Available for download on Sunday, May 10, 2026