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Adult females in a female-bonded, cercopithecine species such as baboons are characterized by hierarchically ranked matrilines, i.e., female offspring assume rankings just beneath those of their mothers. In this system of closely ranked matrilines, a female should engage in significantly more affiliative interactions with those individuals who are closely ranked to herself than with those individuals who are more distantly ranked. We examine the hypothesis that females in this troop of feral yellow baboons (Papio hamadryas cynocephalus ) who are closely ranked will also show close social affiliation. We collected focal data on 23 feral, adult female subjects (253 possible dyads) over approximately 1 year at the Tana River National Primate Reserve, Kenya. Following Bramblett's [Behav Brain Sci 4: 435, 1981] method of dominance tabulation and utilizing a modified version of Smuts' [Sex and friendship in baboons, Hawthorne: Aldine Publishing Co., 1985] preferred partner index, we describe and compare the dominance matrix and hierarchy, preferred proximity partner and grooming partner sociograms, and the social networks of these 23 focal females. Over 1,400 interactions were utilized in the dominance tabulations, 41 statistically significant proximity partner preferences were documented, and 100 grooming dyads were recorded. We examine both partners' ranks and the presence of an infant as possible factors influencing proximity and grooming partner preferences. We find that in this population there is no direct correspondence between females' ranks and their affiliation partners. Neither proximity nor grooming preferences are consistently predictable from partners' ranks. While proximity preferences were not significantly influenced by the presence of an infant, grooming partner preferences were. Females with infants had more grooming partners and were more often involved in unidirectional grooming relationships as the recipients than were females without infants. We conclude that females' dominance rankings are not good predictors of either proximity partner or grooming partner preferences and that the presence of an infant does have a significant impact on grooming partner preferences in this population. Am. J. Primatol. 47:321–334, 1999. © 1999 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

We have previously studied the relationship between social subordinance (by approach-avoidance criteria) and physiology among male olive baboons (Papio anubis) living freely in a national park in Africa. In stable hierarchies, subordinate individuals have elevated basal glucocorticoid concentrations and a blunted glucocorticoid response to stress, as well as a prompt suppression of testosterone concentrations during stress. These facets have been interpreted as reflecting the chronic stress of social subordinance. In the present report, we find that these endocrine features do not mark all subordinate individuals. Instead, endocrine profiles differed among subordinate males as a function of particular stylistic traits of social behavior. A subset of subordinate males was identified who had significantly high rates of consortships, a behavior usually shown only by high-ranking males. Such behavior predicted the beginning transition to dominance, as these males were significantly more likely than other subordinates to have moved to the dominant half of the hierarchy over the subsequent 3 years. In keeping with this theme of emerging from subordinance, these individuals also had significantly larger glucocorticoid stress-responses, another feature typical of dominant males. However, these subordinate males also had significantly elevated basal glucocorticoid concentrations; it is suggested that this reflects that stressfulness of their overt and precocious strategy of reproductive competition. In support of this, subordinate males with high rates of covert “stolen copulations” did not show elevated basal glucocorticoid concentrations. A second subset of subordinate males were the most likely to initiate fights or to displace aggression onto a third party after losing a fight. These males had significantly or near-significantly elevated testosterone concentrations, compared to the remaining subordinate cohort. Moreover, these males had significantly lower basal glucocorticoid concentrations; this echoes an extensive literature showing that the availability of a displacement behavior (whether aggressive or otherwise) after a stressor decreases glucocorticoid secretion. In support of this interpretation suggesting that it was the initiation of these aggressive acts which attenuated glucocorticoid secretion, there was no association between glucocorticoid concentrations and participation (independent of initiation) in aggressive interactions. Thus, these findings suggest that variables other than rank alone may be associated with distinctive endocrine profiles, and that even in the face of a social stressor (such as subordinance), particular behavioral styles may attenuate the endocrine indices of stress. Am. J. Primatol. 42:25–39, 1997. © 1997 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Dispersals by subadult or adult male baboons are common. In contrast, the occasional transfer of aged baboons is puzzling, given the physical dangers of transfer and the cognitive demands of mastering the ecological and social rules of a new troop. The present data suggest a possible explanation for such transfers in a study of two troops of olive baboons (Papio anubis) in Kenya. Aged males who remained in the troop in which they had been dominant were subjected to significantly higher rates of approach-avoid interactions by the current high-ranking cohort (i.e, the individuals they had dominated years past) when compared to males who had transferred into the troop m their old age. Thus, transfer in old age offers the advantage of relative anonymity. Of the 14 males who progressed into older adulthood in the same troop in which they were in their prime, seven ultimately transferred to a different troop. The seven who remained and the seven who transferred did not differ in the rate at which they were subjected to approach-avoid interactions. However, those who remained had significantly higher rates of venous affiliative behaviors (copulations, consortships, grooming and contact with females, and positive interactions with infants). Thus, amid the disadvantages of an old age spent in the troop in which a male baboon was in his prime, a high degree of social affiliation might constitute a sufficient disincentive against transferring. [ABSTRACT FROM AUTHOR]

In a population of wild baboons living in East Africa, we have observed endocrine differences among individuals as a function of dominance rank. Among these differences, we previously observed indirect evidence for dominant males being more responsive to sympathetic catecholamines than were subordinate males. The present report tests this explicitly. Male baboons of known rank were anesthetized, and sympathetic and parasympathetic activity was pharmacologically inhibited. In experiment I, males were challenged with epinephrine; over a wide dose range, dominant males had the largest and fastest rises in systolic pressure, the greatest peak systolic pressure, and the most rapid recovery from the epinephrine challenge. Similar rank-related differences in heart rate response to epinephrine also occurred. Experiment II showed that this phenomenon probably reflects rank-related differences at both the heart and vasculature. As evidence, the same rank differences in systolic blood pressure responsiveness occurred when males were challenged with the alpha receptor agonist phenylephrine (which predominantly constricts systemic veins and arterioles), while the same rank differences in heart rate responses occurred following stimulation with the beta receptor agonist isoproterenol (which selectively works at the heart). These data were obtained from animals stressed by anesthetization, known to cause considerable glucocorticoid secretion in this population. Such steroids are well known for their capacity to augment catecholamine action. In experiment III, we blocked endogenous glucocorticoid secretion with the steroidogenesis inhibitor metyrapone, and repeated the epinephrine challenge. Under these conditions, the rank differences in epinephrine responsiveness were eliminated. Thus, dominant males are not so much preferentially sensitive to catecholamine action, as much as to the potentiating effects of glucocorticoids upon such action. [ABSTRACT FROM AUTHOR]

We have studied the relationship between dominance rank and physiology among male olive baboons (Papio anubis) living freely in a national park in Africa. In stable hierarchies, dominant males consistently have lower basal concentrations than do subordinates of the adrenal glucocorticoid cortisol. Because of the known catabolic actions of glucocorticoids, dominant males may be less at risk for some of the pathogenic consequences of glucocorticoid overexposure. We find that low basal cortisol concentration is not, in fact, a marker of social dominance; instead, it is only found among dominant males with a certain style of dominance. Lower basal cortisol concentrations occurred among males with any of the following behaviors: the most marked ability to distinguish between threatening and merely neutral interactions with rivals and, if the former, the greatest likelihood of initiating a fight; the most skill at distinguishing between winning and losing a fight and, if the latter, the greatest likelihood of displacing aggression onto a third party. Collectively, these behaviors suggest high degrees of social skillfulness, control, and predictability over social contingencies, all recognized as psychological features that minimize the pathophysiological impact of stress. Dominant males lacking these behavioral features, in contrast, had as high cortisol concentrations as did subordinate males. Finally, low basal cortisol concentrations were also a feature of males with the longest tenures in the dominant cohort, suggesting that this endocrine dichotomy is meaningful in terms of life histories. [ABSTRACT FROM AUTHOR]