Depression can be induced in a bonnet macaque infant.

Depression is a well-known reaction to separation in all species of macaques studied except the bonnet (M. radiata), in whom this reaction has never before been observed. We have produced the depressive response of postural collapse and social withdrawal in a bonnet infant by altering the social structure of the group in which it lived in a way calculated to interfere whith the species-typical system of social support.