RESPONSES OF FREE-RANGING RHESUS-MONKEYS TO A NATURAL FORM OF SOCIAL SEPARATION .1. PARALLELS WITH MOTHER-INFANT SEPARATION IN CAPTIVITY

Observations of 23 free-ranging rhesus monkey infants on Cayo Santiago , Puerto Rico, indicated that mothers' first postpartum estrous period s were marked by large increases in the amount of time infants were se parated from their mothers, by disturbances in mother-infant relations hips, and by increases in infant distress behavior. When their mothers resumed mating, most infants showed signs of agitation; a few briefly showed indications of depression. Male infants responded to their mot hers' resumption of mating by playing more, whereas females engaged in less play and more allogrooming. The results suggest (a) that basic p arallels exist between the behavioral responses of rhesus infants to t heir mothers' resumption of mating in the field and to forcible separa tion from their mothers in captivity and (b) that early separation exp eriences may play a role in the normal development or manifestation of sex differences in behavior.