High social status males experience accelerated epigenetic aging in wild baboons

Aging, for virtually all life, is inescapable. However, within
populations, biological aging rates vary. Understanding sources of
variation in this process is central to understanding the biodemography of
natural populations. We constructed a DNA methylation-based age predictor
for an intensively studied wild baboon population in Kenya. Consistent
with findings in humans, the resulting “epigenetic clock” closely tracks
chronological age, but individuals are predicted to be somewhat older or
younger than their known ages. Surprisingly, these deviations are not
explained by the strongest predictors of lifespan in this population,
early adversity and social integration. Instead, they are best predicted
by male dominance rank: high-ranking males are predicted to be older than
their true ages, and epigenetic age tracks changes in rank over time. Our
results argue that achieving high rank for male baboons—the best predictor
of reproductive success—imposes costs consistent with a “live fast, die
young” life history strategy.

几乎所有生命的衰老过程都无可避免。然而，在种群内部，个体的生物学衰老速率存在差异。阐明这一过程的变异来源，是理解自然种群生物人口统计学的核心所在。我们针对肯尼亚一处被深入研究的野生狒狒种群，构建了基于DNA甲基化（DNA methylation）的年龄预测模型。与人类中的研究结果一致，由此得到的表观遗传时钟（epigenetic clock）能够精准追踪实际年龄，但部分个体的预测年龄会略高于或低于其已知实际年龄。令人意外的是，这些预测偏差无法用该种群中影响寿命的两大最强预测因子——早期逆境与社会整合——来解释。反之，雄性优势等级（male dominance rank）是最佳预测因子：等级较高的雄性的预测表观年龄会高于其实际年龄，且表观遗传年龄会随时间追踪等级的变化。我们的研究结果表明，对于雄性狒狒而言，获得高等级地位——这是繁殖成功率的最佳预测因子——会带来与“速生早亡”生活史策略相符的生理代价。