A future food boom rescues the negative effects of cumulative early-life adversity on adult lifespan in a small mammal

Adverse early-life conditions, even when transient, can have long-lasting effects on individual phenotypes and reduce lifespan across species. If these effects can be mitigated. by a high quality later-life environment, then differences in future resource access may explain variation in vulnerability and resilience to early-life adversity. Using 32 years of data on 1,000+ wild North American red squirrels, we tested the hypothesis that the negative effects of early-life adversity on lifespan can be buffered by later-life food abundance. We found that although cumulative early-life adversity was negatively associated with adult lifespan, this relationship was modified by future food abundance. Squirrels that experienced a naturally-occurring future food boom in the second year of life did not suffer reduced longevity despite early-life adversity. Experimental supplementation with additional food did not replicate this effect, though it did increase adult lifespan overall. Our results suggest a non-deterministic role for early-life conditions on later-life phenotypes, and highlight the importance of contextualizing the influence of harsh early-life conditions over an animal’s entire life course.