Macaque Stone Handling

Dr. J.-B. Leca and Dr. M. A. Huffman

Japanese macaques (Macaca fuscata) have long been the subject of studies examining the cultural transmission of behavior. Behaviors such as washing and salting potatoes in the sea, floating wheat to remove sand, soaking in hot springs, and even rolling and playing with snowballs emerged as innovations that spread rapidly from the innovator to other individuals in a given troop. More recent research has examined stone handling as a form of solitary object play that is transmitted from generation to generation as a form of behavioral tradition. In these video clips, macaques practice various forms of stone handling. Object play may promote the refinement of motor skills, prevent cognitive deterioration, or effectively test the properties of objects, allowing those to be applied in a novel context where such properties would prove useful.

FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 6, “Cultural Transmission”; chap. 16, “Play.” J.-B. Leca, N. Gunst, and M.A. Huffman, “Of stones and monkeys: Testing ecological constraints on stone handling, a behavioral tradition in Japanese macaques,” American Journal of Physical Anthropology 135 (2008), pp. 233–244.

Scrub Jay Caching Food

Scott Stevens

A western scrub jay (Aphelocoma californica) caches worms in a sawdust-filled tray in the presence of an observing conspecific. When observed by conspecifics, jays cache preferentially in a location far from the observer or in a more dimly illuminated area, but fail to cache preferentially in those locations when allowed the same access to food items and cache sites in private. Further, jays allowed to return to their caches move cached food to new locations if they originally cached with a conspecific observer present, but they do not move items to new locations if they originally cached in private. Like ravens that selectively cache behind obstacles when in the presence of potential pilfering conspecifics, this finding suggests that jays have the cognitive capacity to infer when conspecifics represent a threat to their cached food stores, and as such, possess an underlying theory of mind (the capacity to think about the thoughts and feelings of others).

FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 6, “Cultural Transmission.” J. M. Dally, N. J. Emery, and N. S. Clayton, “Cache protection strategies by western scrub-jays, Aphelocoma californica: Implications for social cognition,” Animal Behaviour 70 (2005), pp. 1251–1263.