Nature vs. Nurture in Monkey Communication: The Effects of Experience on the Development of Emotional and Referential Content in Rhesus Macaque (Macaca mulatta) Vocalizations

This book describes the results of a cross-fostering experiment to investigate the effects of experience on emotional and informational content in rhesus macaque (Macaca mulatta) vocal communication. The subjects of the study were twelve rhesus macaques: six were foster-reared by abusive mothers and six were foster-reared by control mothers. Vocalizations were recorded from the subjects in their social groups for two years. The acoustic variables measuring positive emotional expression were lower in abused than control subjects. On the other hand, abused subjects expressed exaggerated levels of fear during mild contact aggression with other animals. The second part of the study statistically classified the calls of cross-fostered monkeys to either their biological or foster family. In the present study, matrilineal signatures were clearly discriminated among different families of rhesus macaques. Furthermore, the calls of the majority of cross-fostered subjects classified to the foster matriline, suggesting that these signatures were learned rather than inherited.

Tanja Jovanovic graduated from the Neuroscience and Animal Behavior Program at Emory University Psychology Department in 2002. Her graduate work focused on emotion in non-human primates. She is currently on the faculty of Emory University Department of Psychiatry in Atlanta where she studies emotion in humans with psychiatric conditions.