Focused grooming networks and stress alleviation in female baboons
We examine the relationship between glucocorticoid (GC) levels and grooming behavior in wild
female baboons during a period of instability in the alpha male rank position. All females' GC levels rose
significantly at the onset of the unstable period, though levels in females who were at lower risk of infanticide
began to decrease sooner in the following weeks. Three factors suggest that females relied on a focused
grooming network as a coping mechanism to alleviate stress. First, all females' grooming networks became
less diverse in the weeks following the initial upheaval. Second, females whose grooming had already
focused on a few predictable partners showed a less dramatic rise in GC levels than females whose
grooming network had been more diverse. Third, females who contracted their grooming network the most
experienced a greater decrease in GC levels in the following week. We conclude that close bonds with a few preferred partners allow female baboons to alleviate the stress associated with social instability.
Social stressors and coping mechanisms in female baboons
We examined the social correlates of fecal glucocorticoid (GC) levels in wild female baboons during a period of social and demographic stability. Females’ GC levels were not affected by individual attributes such as number of kin or dominance rank, nor could we detect any significant seasonal effects. Instead, GC levels were influenced by behavioral attributes that varied between individuals and within individuals across time. Pregnant and cycling females who received high rates of aggression had higher GC levels than others. In contrast, pregnant and cycling females who received grunts – vocal signals of benign intent – at high frequencies from dominant females had lower GC levels than females who received grunts at lower frequencies. Lactating females showed the opposite trend, apparently as a consequence of the high rate of grunting and intense, unsolicited attention that their infants received from others. All females experienced lower GC levels in months when they concentrated their grooming among a small number of partners than when their grooming was more evenly distributed among many partners. Although GC levels in female baboons are most strongly influenced by events that directly affect their reproductive success, subtle social factors associated with the loss of predictability and control also seem to exert an effect. Loss of control may be mitigated if a female is able to predict others’ intentions – for example, if others grunt to her to signal their intentions – and if she able to express some preference over the timing and identities of her grooming partners.
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