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. The responses of subjects to experimental manipulations 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 and circumstances. This past year we initiated a pilot study to see if rhesus monkey neonates were capable of ?imitating? specific facial expressions and hand movements directed toward them by a human ?model.? in their initial days of life. Such early imitative capabilities have been reported for human neonates and they are thought to be reflexively mediated by ?mirror? neurons, a recently characterized class of visual-motor neurons found in Area F5 of the ventral premotor cortex. Preliminary findings indicated that some (but not all) rhesus monkey newborns were able to mimic specific facial expressions involving differential mouth and tongue movements, but not until their second or third day of life. Interestingly, those individual infants who demonstrated this imitative capacity spent significantly more time visually focusing on facial stimuli on Day 1 than those who did not exhibit any imitative behaviors on subsequent days. We are now testing additional infants and are carrying out follow-up behavioral observations and biological sampling of the original infants to determine if these individual differences in early imitative capabilities are predictive of individual differences in biobehavioral functioning throughout subsequent development. This past year we also completed the most of the analyses of behavioral and biological data collected in a study in which some nursery-reared rhesus monkey infants (?masters?) were given operant control over access to highly desirable food treats, whereas other nursery reared infants (?yoked controls?) received the same treats in the absence of any control. Analyses of behavioral and neuroendocrine data collected both in the infants? home cages and in a novel environment indicated that the ?master? subjects engaged in more exploratory and less anxious-like behavior, and had lower levels of HPA activity, than their yoked control counterparts. Additional analyses of CSF monoamine metabolite concentrations obtained throughout the study are currently underway. Data collection for a long-term prospective longitudinal study of maternal behavior across three successive generations of rhesus monkey females born and raised in the LCE?s 5-acre outdoor field enclosure was completed this past year. Analyses of these data should enable us to determine the degree to which specific patterns of maternal behavior exhibited by females toward successive offspring resemble those exhibited by their mothers and grandmothers in both previoouss and (for those older females who continue to produce and rear offspring) concurrent years in each year?s birth cohort. Analyses of immunological data collected in another long-term prospective longitudinal study of free-ranging rhesus monkeys residing on the island of Cayo Santiago in Puerto during the annual trapping of monkeys (for veterinary examinations) revealed a significant relationship between measures of immune system and HPA axis functioning and maternal dominance status in juvenile subjects. Monkeys whose mothers were low-ranking within their natal social groups exhibited higher cytotoxicity, greater numbers of C8 and C16 Raij targets, and higher concentrations of plasma cortisol than offspring of more dominant mothers, demonstrating that differences in maternal rank have significant consequences not only for offspring social and emotional development but also for immune system and adrenocortical functioning. Tool-using capabilities in juvenile rhesus monkeys was assessed for a task routinely solved by most capuchin monkeys. Subjects were required to use a rake to retrieve a reward located outside the cage. In the tube task, monkeys had to use a PVC pipe to remove a reward from a tube. Substantial individual differences in capability were revealed for the sample of 8 rhesus monkeys tested. Two monkeys quickly solved the tool using tasks, and three monkeys eventually solved the tool-using task. Two monkeys showed partial understanding of the tool-using task but could not reliably obtain a reward, and the eighth rhesus subject failed both tasks. Successful tool users showed persistence in the task and varied their responses. Key to their success was learning to push a tool away from them rather than pull it toward them. Unsuccessful monkeys became fixated on nonproductive strategies. A final study investigated the relationship between social dominance ranking and food consumption as a function of food novelty and relative accessibility in a group of tufted capuchin monkeys. High-ranking group members consumed significantly more food that was easily accessible than portions that were hidden from view, whereas the reverse was true for low-ranking subjects. Rates of aggressive threats by high-ranking monkeys toward lower-ranking individuals were inversely related to the amount of food consumed by low-ranking group members. Thus, although tufted capuchin monkeys have been described as a relatively peaceable species (at least compared with rhesus monkeys) and readily share food in a variety of naturalistic and captive situations, there are dominance-related differences in food consumption that appear to be mediated by differences in the relative occurrence and direction of threat behavior.
| 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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