Relationship Between Social Rank and Cortisol and Testosterone Concentrations in Male Cynomolgus Monkeys (Macaca fascicularis) (original) (raw)
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Journal of Neuroendocrinology, 2009
In nonhuman primate social groups, biological differences related to social status have proven useful in investigating mechanisms of sensitivity to various disease states. Physiological and neurobiological differences between dominant and subordinate monkeys have been interpreted in the context of chronic social stress. The present experiments were designed to investigate the relationships between basal cortisol and testosterone concentrations and the establishment and maintenance of the social hierarchy in male cynomolgus monkeys. Cortisol concentrations were measured at baseline and following suppression with dexamethasone (DEX) and subsequent administration of ACTH while monkeys were individually housed (n=20) and after 3 months of social housing (n=4/group), by which time dominance hierarchies had stabilised. Cortisol was also measured during the initial three days of social housing. Neither pre-social housing hormone concentrations nor HPA axis sensitivity predicted eventual social rank. During initial social housing, cortisol concentrations were significantly higher in monkeys that eventually became subordinate; this effect dissipated within three days. During the 12 weeks of social housing, aggressive and submissive behaviours were observed consistently, forming the basis for assignment of social ranks. At this time, basal testosterone and cortisol concentrations were significantly higher in dominant monkeys and, following dexamethasone suppression, cortisol release in response to a challenge injection of ACTH was significantly greater in subordinates. These results indicate that basal cortisol and testosterone concentrations and HPA axis function are state variables that differentially reflect position in the dominance hierarchy, rather than trait variables that predict future social status.
Behavioural Processes, 2014
Please cite this article in press as: Mendonç a-Furtado, O., et al., Does hierarchy stability influence testosterone and cortisol levels of bearded capuchin monkeys (Sapajus libidinosus) adult males? A comparison between two wild groups. Behav. Process. (2014), http://dx.a b s t r a c t Testosterone and cortisol are hormones expected to play a major role in competitive behaviours (i.e. aggression), and are related to rank and hierarchical stability. Through a non-invasive technique, we analyzed faecal testosterone (FTM 1 ) and cortisol (FCM 2 ) metabolites of dominant and subordinate males from two wild groups of bearded capuchin monkeys. One group had a stable dominance hierarchy while the other had an unstable hierarchy, with a marked conflict period related to a male take-over. In the unstable hierarchy group (1) the dominant male had higher FTM peaks than subordinates, and (2) basal FTM levels were higher than in the stable group. These findings are in accordance with the Challenge Hypothesis and rank-based predictions, and confirm that in Sapajus libidinosus hierarchy stability, social status, aggression rates and testosterone are closely related. Dominants of both groups had higher basal and peak FCM levels, suggesting that in S. libidinosus the dominant male has a higher allostatic load than subordinates, related to his role in protection against predators, intragroup appeasement, and control of food sources. Finally, we suggest that males of S. libidinosus are resistant to testosterone suppression by cortisol, because in the unstable group in spite of an increase in FCM there was also an increase in FTM during the conflict period.
Dominance, Cortisol, and Behavior in Small Groups of Female Cynomolgus Monkeys (Macaca fascicularis)
Hormones and Behavior, 2001
The relationships among social rank, basal cortisol concentrations, and social behavior were assessed in adult female cynomolgus monkeys (Macaca fascicularis). Subjects were 157 unrelated, reproductively intact animals housed in 30 small groups. Rank determinations were made monthly. Blood samples were collected on two occasions, 4.5 and 7.5 months following initial group formation. Regular behavioral observations were conducted on a subset of animals over a period of 4 weeks, 9 months following group formation. Analyses revealed that serum cortisol values were significantly correlated across the two sampling periods, with no significant change in absolute values. While social rank was positively correlated across both samples, there was no relationship between rank and cortisol. However, dominant and subordinate animals did differ in the rates of performance of aggressive and submissive behaviors. These data suggest that social rank does not influence baseline serum cortisol in adult female cynomolgus monkeys, despite stability in measures of rank and cortisol and the presence of the usual behavioral differences between dominants and subordinates.
American Journal of Primatology, 2019
Social status impacts stress in primates, but the direction of the effect differs depending on species, social style, and group stability. This complicates our ability to identify broadly applicable principles for understanding of how social status impacts health and fitness. One reason for this is the fact that social status is often measured as linear dominance rank, yet social status is more complex than simply high or low rank. Additionally, most research on social status and health ignores the effects of sex and sex-specific relationships, despite known differences in disease risk, coping strategies, and opposite-sex dominance interactions between males and females in many species. We examine the influence of social status, sex, and opposite-sex interactions on hair cortisol concentrations in a well-studied species, rhesus macaques, where the literature predicts low ranking individuals would experience more chronic stress. Animals in three captive, seminaturalistic social groups (N = 252, 71 male) were observed for 6 weeks to obtain metrics of social status (rank and dominance certainty (DC)). DC is a measure of one's fit within the hierarchy. Hair samples were collected from each subject and analyzed for hair cortisol concentrations (HCC). Generalized linear mixed models were used to examine 1) whether rank, DC, or sex predicted HCC, 2) whether same-or opposite-sex dominance relationships differentially impacted HCC, and 3) whether aggressive interactions initiated or received could explain any observed relationships. Results indicated that DC, not rank, predicted HCC in a sex-specific manner. For males, high HCC were predicted by receiving aggression from or having high DC with other males as well as having low DC with females. For females, only high DC with males predicted high HCC. These results likely relate to sex-specific life history pattern differences in inherited versus earned rank that are tied to female philopatry and male immigration.