In social hierarchies, dominant individuals experience reproductive and health benefits, but the costs of social dominance remain a topic of debate. Prevailing hypotheses predict that higher-ranking males experience higher testosterone and glucocorticoid (stress hormone) levels than lower-ranking males when hierarchies are unstable but not otherwise. In this long-term study of rank-related stress in a natural population of savannah baboons (Papio cynocephalus), high-ranking males had higher testosterone and lower glucocorticoid levels than other males, regardless of hierarchy stability. The singular exception was the highest-ranking (alpha) males, who exhibited both high testosterone and high glucocorticoid levels. In particular, alpha males exhibited much higher stress hormone levels than second-ranking (beta) males, suggesting that being at the very top may be more costly than previously thought.
Raw hormone data
This data file contains the monthly average hormones values for glucocorticoids (GC) and testosterone (T), for each of the 127 adult male baboons, used in the analyses for this article.
Residual hormone data fig1
This data file gives for each rank the residuals of log-transformed hormone concentration (glucocorticoids and testosterone) obtained from a GLMM (for that hormone) that included age, environmental factors and hierarchy stability as fixed factors, male identity as a random factor. Each row represents a month-year value for a single male. Details on the analysis can be found in the publication.
Residual hormone data fig2
This data file contains four tables that each give for each rank the residuals of log-transformed hormone concentration (glucocorticoids and testosterone) obtained from a GLMM (separate for each hormone) that included age and environmental factors as fixed factors, and male identity as a random factor. Each row represents a month-year value for a single male. A different dataset was used for each table as follows. For tables 'All ranks_Stable' and 'All ranks_Unstable' the associated GLMM model used data for males of all ranks but only during months for which the hierarchy was 'stable' or 'unstable' respectively. For tables 'Rank 1&2_Stable' and 'Rank 1&2_Unstable', which provide the data for the Fig.2 inserts, the associated GLMM model used data only for alpha and beta males and only during months for which the hierarchy was 'stable' or 'unstable’ respectively. Details of the analysis can be found in the publication.
Alpha beta comparison fig3
This data file contains four tables: -‘Reversal’: gives for each alpha/beta pair the proportion of challenges that the alpha and the beta male experienced as well as the difference in these proportions. -‘Grooming received’: gives for each alpha/beta pair the average rate of grooming that the alpha and beta male received as well as the difference in these rates. -‘Agonism’: gives for each alpha/beta pair the average rate of agonistic interaction for the alpha and beta male as well as the difference in these rates. -‘Consort time’: gives for each alpha/beta pair the average time spent in consortship for the alpha and beta male as well as the difference in these times. See online supplement of this publication for more details.
