This project investigates how rhesus monkeys and other nonhuman primate species born and raised under different laboratory conditions adapt to placement into environments that contain specific physical and social features of the monkey's natural habitat. Adaptation is assessed by examining behavioral repertoires and by monitoring a variety of physiological systems in these subjects, yielding broad-based indices of relative physical and psychological well-being. The responses of subjects to experimental manipulation of selected features of their respective environments are also assessed in similar fashion. Whenever possible, field data are collected for appropriate comparisons. An additional focus is on investigating the cognitive, behavioral, and social processes involved in adaptation to new settings or circumstances. In this program of research adaptation is assessed by examining behavioral repertoires and by monitoring a variety of physiological systems in monkeys throughout the lifespan, yielding broad-based indices of relative physical and psychological well-being. This past year we completed the analysis of data collected on mother-offspring pairs of rhesus monkeys residing in two free-ranging social groups at the field site at Cayo Santiago, PR throughout the offsprings' first two years of life to determine the degree to which individual differences in their behavior were related to individual differences in a variety of psychophysiological, endocrine, and morphometric measures in the offspring and in their mothers. Offspring showed stable individual differences in heart rate following capture for veterinary examination from their first to second year, as well as in plasma concentrations of cortisol and prolactin and in virtually all morphometric measures. Body mass index and plasma concentrations of cortisol and growth hormone in offspring and their mothers were unrelated when the offspring were yearlings but became significantly correlated by the time the offspring were two years old. Mothers with low cortisol levels punished their infants more, whereas mothers with high cortisol levels showed the highest rate of infant carrying. Offspring exhibiting the highest frequencies of agitated behavior throughout the study also exhibited the highest cortisol levels following capture. These findings suggest that morphological and physiological patterns of mothers are related to their offsprings' behavior and physiology via developmental experience as well as through genetic/intrauterine factors. The relationships between measures of neurobiological functioning and various dimensions of maternal behavior were also investigated in a ongoing study of rhesus monkey mother-offspring pairs living in the species-normative social group maintained in the LCE's 5-acre field enclosure at the NIHAC. CSF samples were collected from mothers when their infants were 3-5 months of age and assayed for 5-HIAA and HVA; the resulting values were then compared with different aspects of maternal behavior recorded when their infants were 1-3, 4-6, and 7-9 months old, respectively. Measures of maternal protectiveness and infant restraint during the latter two time periods were negatively correlated with both mothers'5-HIAA and HVA concentrations. In contrast, measures of two forms of active infant rejection were positively correlated with concentrations of both monoamine metabolites during the latter two time periods, whereas the rate of passive rejections was not significantly related to concentrations of either metabolites during any time period. Another study investigating mother-infant relationships in rhesus monkeys housed in the LCE field enclosure compared primiparous with multiparous females with respect to various aspects of their maternal behavior and that of their infants. Offspring of multiparous females were more active than were primiparous infants during their first month of life, initiating and breaking contact with and approaching and leaving their mothers more frequently than their primiparous counterparts. Primiparous mothers exhibited higher rates of initiating ventral contact with their infants, as well as initiating nipple contact, throughout most of their infant's first 5 months of life. These findings parallel parity differences in mother-infant relationships previously reported from field studies of rhesus monkeys and several other Old World monkey species. Finally, a study examining continuity and change in patterns of adrenocortical functioning throughout the juvenile years in rhesus monkeys reared in 3 different physical and social environments for their first 7 months of life but thereafter placed together and subsequently maintained in large peer groups was completed and the results accepted for publication. Monkeys from all 3 rearing conditions (mother-peer, surrogate-peer, and peer-only) exhibited significant increases in plasma cortisol over their first 5 months but then showed steady declines from 1 to 3 years of age; females consistently had higher concentrations than males at all ages. Plasma cortisol levels of surrogate-peer reared subjects were lower than were those of their mother-peer reared counterparts (with peer-only reared subjects intermediate) during the first month of life but not at later ages. Juvenile cortisol levels were significantly correlated with infant levels in all samples collected after two weeks of age, indicating long-term developmental stability of individual differences. Saliva samples were collected from a subset of these subjects at 1, 2, and 3 years. Analysis of salivary cortisol concentrations from this subgroup revealed a significant age-related decline, as well as lower levels for surrogate-peer reared monkeys at each age, but no significant sex differences at any age. Comparison of salivary and plasma cortisol values obtained from the same subjects yielded a highly significant positive correlation.
| Ruggiero, Angela M; Novak, Matthew F S X; Woodward, Ruth A et al. (2009) Successful behavioral strategy to unite mother and infant rhesus monkeys (Macaca mulatta) after cesarean delivery. Am J Primatol 71:510-22 |
| Byrne, Gayle; Suomi, Stephen J (2009) Intimate social behavior in infant interactions in Cebus apella. Am J Primatol 71:77-85 |
| Miller, Kimran E; Laszlo, Katalin; Suomi, Stephen J (2008) Why do captive tufted capuchins (Cebus apella) urine wash? Am J Primatol 70:119-26 |
| Novak, Matthew Fsx; Kenney, Caroline; Suomi, Stephen J et al. (2007) Use of animal-operated folding perches by rhesus macaques (Macaca mulatta). J Am Assoc Lab Anim Sci 46:35-43 |
| Lutz, Corrine K; Davis, Ernie B; Ruggiero, Angela M et al. (2007) Early predictors of self-biting in socially-housed rhesus macaques (Macaca mulatta). Am J Primatol 69:584-90 |
| Roma, Peter G; Silberberg, Alan; Huntsberry, Mary E et al. (2007) Mark tests for mirror self-recognition in capuchin monkeys (Cebus apella) trained to touch marks. Am J Primatol 69:989-1000 |
| Roma, Peter G; Champoux, Maribeth; Suomi, Stephen J (2006) Environmental control, social context, and individual differences in behavioral and cortisol responses to novelty in infant rhesus monkeys. Child Dev 77:118-31 |
| Roma, Peter G; Silberberg, Alan; Ruggiero, Angela M et al. (2006) Capuchin monkeys, inequity aversion, and the frustration effect. J Comp Psychol 120:67-73 |
| Silberberg, Alan; Roma, Peter G; Ruggiero, Angela M et al. (2006) On inequity aversion in nonhuman primates. J Comp Psychol 120:76 |
| Suomi, Stephen J (2005) Aggression and social behaviour in rhesus monkeys. Novartis Found Symp 268:216-22; discussion 222-6, 242-5 |
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