Social status predicts wound healing in wild baboons

Abstract

Social status can have striking effects on health in humans and other animals, but the causes often are unknown. In male vertebrates, status-related differences in health may be influenced by correlates of male social status that suppress immune responses. Immunosuppressive correlates of low social status may include chronic social stress, poor physical condition, and old age; the immunosuppressive correlates of high status may include high testosterone and energetic costs of reproduction. Here we test whether these correlates could create status-related differences in immune function by measuring the incidence of illness and injury and then examining healing rates in a 27-y data set of natural injuries and illnesses in wild baboon males. We found no evidence that the high testosterone and intense reproductive effort associated with high rank suppress immune responses. Instead, high-ranking males were less likely to become ill, and they recovered more quickly than low-ranking males, even controlling for differences in age. Notably, alpha males, who experience high glucocorticoids, as well as the highest testosterone and reproductive effort, healed significantly faster than other males, even other high-ranking males. We discuss why alpha males seem to escape from the immunosuppressive costs of glucocorticoids but low-ranking males do not, including the idea that glucocorticoids' effects depend on an individual's physiological and social context.

Group augmentation, collective action, and territorial boundary patrols by male chimpanzees

“…High-ranking males often sire many offspring, but a positive relationship between rank and participation in patrols that occurs independently of rank-related variation in reproductive success would indicate that relative paternity success is an insufficient explanation for variation in patrolling (48,(55)(56)(57)(58). One likely possibility is that high-ranking individuals experience relatively low costs of patrolling because of their superior physical condition (59)(60)(61). Consistent with this prediction, dominance rank was positively related to patrol participation (Table 1).…”

Evolutionary medicine: its scope, interest and potential

“…Substantial evidence suggests that oxytocin, testosterone and cortisol correlate with social behaviours [148,149].…”

“…The trade-offs among these systems need to be much better understood, especially in longterm field studies in which individual primates are identified and followed [148].…”

Social information changes the brain

“…In animals, there are plentiful examples of the importance of rank on biological systems. In rhesus macaques (Macaca mulatta), for example, social rank regulates the immune system, with low-status individuals increasing gene expression in their immune response to inflammation (4), and social status predicts wound healing rate in wild baboons (Papiocynocephalus anubis) (5). Although rank must alter health through specific mechanisms, little is known about the biological representations and consequences of social stratification.…”