Monkey Medicine: The social and medicinal functions of anointing in robust capuchin monkeys (Sapajus apella)

Emily Messer (Heriot-Watt University)

Anointing is a behaviour where animals apply pungent-smelling materials over their bodies. Wild and captive capuchin monkeys will anoint themselves individually and socially (in contact with each other) with various materials, including millipedes, limes, and onions. Hypotheses for the function of anointing range from medicinal to social. By manipulating the abundance of an anointing resource given to two groups of tufted capuchins and measuring their levels of anointing and proximity patterns during and shortly after anointing compared to a baseline condition, we tested predictions of social and medicinal functions. Despite group differences, our results suggest a role of anointing in mediating social relations with increases in proximity after anointing and in targeting hard-to-see and hard-to-reach body parts while anointing individually and socially, respectively. This suggests that anointing in capuchins is, in part, analogous to social grooming. Both behaviours have an antiparasitic function and can be done individually or socially, requiring contact between two or more individuals. This alternative ‘social medication’ perspective avoids treating medicinal and social explanations of anointing as alternative hypotheses and provides increasing support for the medical explanations for anointing.

In-person: David Brewster 1.15, Heriot-Watt University, Edinburgh.