The Troubles of Being Female: Investigating the relationship between social status and stress level in a population of adult female yellow baboons in Amboseli, Kenya

Alberts, Susan C

Jackson, Brie

2016-04-26T02:58:13Z

2016-04-26T02:58:13Z

2016-04-25

Biology

The famous Whitehall studies of the social determinants of health suggest that low social status has a negative effect on a person’s health due to a high level of chronic stress. Glucocorticoid hormone (GC) is released in the body as a direct response to stress, and is involved in important anti-inflammation and immunosuppression reactions that allow quick responses to stressful stimuli. For this reason, persistent and high levels of GC resulting from prolonged stress are thought to confer lower fitness by inhibiting immunity, producing a lower quality of life, and causing shorter longevity. There are many other examples of low dominance rank conferring lower fitness in animals, but this effect is species-dependent because subordinate animals can retain benefits as well. Thus, it is scientifically interesting to determine the direction of this effect in primate species. This study aimed to discover the relationship between social rank and stress in the adult female population of yellow baboons in the Amboseli Basin of Kenya. A previous study of male Amboseli baboons found that, with one exception, there is a negative relationship between high male rank and stress level. This information helped lead to the hypothesis that there is a negative correlation between high female rank and stress level. To test this hypothesis, the analysis used longitudinal data from over 12,000 samples collected over a 13-year period (2000-2013) from 191 adult females. Generalized Linear Mixed Models (GLMMs) were used to predict the effect of social rank on stress, as measured by fecal glucocorticoid concentrations. Other factors such as age, reproductive status, and environmental conditions were entered into the models as fixed effects and individual female identities were entered as a random factor. The results showed no significant relationship between a female’s numerical rank and her stress level. Instead, it was determined that a female’s proportional, or relative, rank affects her stress such that lower ranking individuals have higher stress. Though the final results supported the initial hypothesis, the insignificance of numerical rank was surprising.

https://hdl.handle.net/10161/11867

baboon, glucocorticoid, stress, dominance rank, proportional rank

The Troubles of Being Female: Investigating the relationship between social status and stress level in a population of adult female yellow baboons in Amboseli, Kenya

Honors thesis