Date of Award

Spring 5-15-2018

Author's School

Graduate School of Arts and Sciences

Author's Department


Degree Name

Doctor of Philosophy (PhD)

Degree Type



Vocal communication is integral to primate social interactions. Understanding the evolutionary drivers that have led to increased vocal complexity in primates can facilitate our understanding of primate sociality and the faculties underpinning human language. Callitrichids, cooperatively breeding New World primates, are often used as models for the evolution of complex vocal communication. Cooperative breeding is thought to promote communicative complexity due to the need to coordinate parenting behaviors; callitrichids are the only cooperative breeders in the order Primates besides humans, and they exhibit context-specific vocalizations that convey information about endogenous and exogenous factors. In this dissertation I assess complexity in tamarin mobbing alarm calls and contact calls.

In the first chapter I examine the role of predation in promoting the use of discrete, context-specific anti-predator vocalizations. I found that while the predominant mobbing vocalization did not differ reliably between contexts, other vocalizations were more likely to be present in some contexts than others. This finding supports earlier work indicating that mobbing calls are indicators of high arousal and suggests that other vocalizations reduce ambiguity by transmitting context-specific vocalizations to conspecifics. In the second and third chapters, I investigate the transmission of identity signals in callitrichid long distance vocalizations. Results indicate that long calls transmit sex, age, identity, group, and breeding status, and that these differences are attended to by conspecifics. Given the obstacles to reproductive success faced by cooperative breeders with high reproductive skew, these findings suggest that tamarins might use these calls to facilitate dispersal and locate potential mates.

Alarm calls and contact calls are ubiquitous in primates, and predation and the processes of dispersal and mate choice are arguably two of the strongest selective pressures on a primate. These results have implications for the roles of predation and dispersal in promoting communicative complexity in cooperatively breeding species. They may also shed light on the social origins of the sociocognitive adaptations that underlie complex communication.


English (en)

Chair and Committee

Crickette Sanz

Committee Members

Krista Milich, David Strait, Erik Trinkaus, Mrinalini Watsa,


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