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.

在社会等级体系中，优势个体能够获得繁殖与健康收益，但社会支配地位的代价仍存在争议。主流假说预测，当等级体系不稳定时，地位更高的雄性个体的睾酮（testosterone）与糖皮质激素（glucocorticoid，应激激素）水平会高于地位较低的雄性，而在等级稳定时则无此差异。本项针对草原狒狒（Papio cynocephalus）自然种群中等级相关应激的长期研究显示，无论等级体系是否稳定，地位较高的雄性个体的睾酮水平均高于其他雄性，而糖皮质激素水平则更低。唯一的例外是地位最高的阿尔法（alpha）雄性，它们同时表现出较高的睾酮与糖皮质激素水平。尤为值得注意的是，阿尔法雄性的应激激素水平远高于排名第二的贝塔（beta）雄性，这表明身处等级顶端的代价或许比此前预想的更高。