Data from: Life at the top: rank and stress in wild male baboons

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.