Differential effects of early life adversity on male and female rhesus
macaque lifespan
Abstract
Early life adversity predicts shorter adult lifespan in several animal
taxa. Yet, work on long-lived primate populations suggests the evolution
of mechanisms that contribute to resiliency and long lives despite early
life insults. Here, we tested associations between individual and
cumulative early life adversity and lifespan on rhesus macaques at the
Cayo Santiago Biological Field Station using 50 years of demographic
data. We performed sex-specific survival analyses at different life
stages to contrast short-term effects of adversity (i.e., infant
survival) with long-term effects (i.e., adult survival). Rhesus macaques
exposed to adversity at birth suffered a significant increase in
mortality risk during infancy with both individual and cumulative
adversities having the highest impact among affected females. However,
when considering adult lifespan, affected males showed higher
vulnerability to both individual and cumulative adversities early in
life. Our study shows profound immediate effects of insults at birth on
female infant cohorts and suggests that affected female adults are more
robust (i.e., viability selection). In contrast, adult males who
experienced harsh conditions early in life showed an increased mortality
risk at older ages as expected from hypotheses of long-term effects of
individual, as well as cumulative, adversity early in life. Our study
reveals that mortality risk during infancy is mainly driven by the type
of adversity, rather than their accumulation at birth. However,
cumulative adversity seems to play a major role in adult survival. Our
analysis suggests sex-specific selection pressures on life histories and
highlights the need for studies addressing the effects of early life
adversity across multiple life stages. This information is critical for
planning life stage-specific strategies of conservation interventions.