Monkeys reared in isolation from birth to 9 months received varied visual input solely from colored slides of monkeys in various activities and from nonmonkey pictures. Exploration, play, vocalization, and disturbance occurred most frequently with pictures of monkeys threatening and pictures of infants. From 2.5 to 4 months threat pictures yielded a high frequency of disturbance.Lever-touching to turn threat pictures on was very low during this period. Pictures of infants and of threat thus appear to have prepotent general activating properties, while pictures of threat appear to release a developmentally determined, inborn fear response.
Previous studies have reported that the maternal behavior of rhesus monkey females who themselves were reared without mothers ("motherless mothers") is generally inadequate and often abusive. The present study examined the maternal competency of SO such subjects with respect to the variables of rearing environment, age at first social contact, sex of offspring, age at first delivery, parity, and duration of exposure to previous offspring. The results suggested that physical contact with conspecifics, either with peers prior to adulthood or with their own infants immediately after birth, greatly reduced the probability that motherless mothers would be inadequate maternally.Researchers who have studied the consequences of social deprivation in rhesus monkeys are in virtual agreement that social isolation or restriction imposed early in life has devastating, and often permanent, effects on the social development of monkeys. As adults, monkeys reared for at least the first 6 months in physical isolation from conspecifics have been reported to exhibit anomalies in home-cage behavior (Cross & Harlow, 196S;Suomi, Harlow, & Kimball, 1971), in adaptation to novel environments (Harlow, Schiltz, & Harlow, 1969), in approach to complex stimuli (Sackett, 1972), and in suppression of ongoing response chains (Sackett, 1970). With respect to social activities, adult isolate-reared monkeys typically display excessive and inappropriately directed aggres-
Urinary free cortisol responses to five cage sizes, cage level, room change, tethering adaptation, chronic catheterization, and ketamine sedation were measured in 14 female and 14 male wild-born adult Macaca fascicularis. Urinary free cortisol, a physiological measure of psychological well-being that can be collected unobtrusively, provided a measure of the animals' general adrenocortical response to various conditions over a time course of hours. Urinary free cortisol values in response to stimulation with adrenocorticotropic hormone (ACTH) validated the measure as a reflection of blood values. Cortisol values were expressed as a ratio to creatinine, which normalized for differences in urinary output and body weight (muscle mass). Cage size (20-140% of regulation floor area) and housing level (upper vs. lower cage) had no effect on stress, as measured by cortisol excretion. Room change elicited a slight increase in cortisol excretion for the first day, but not to a level suggesting stress. Sedation, surgery, some aspects of tethering adaptation, and chronic catheterization produced urinary cortisol evidence of stress. Even so, animals varied in their responses and all showed adaptation. Males and females did not differ in normal mean values but females tended to have higher cortisol levels in response to potential stressors investigated in this study. Cortisol levels continued to decline gradually throughout the study. o 1993 Wiley-Liss, Inc.
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