Intergenerational effects of early adversity on survival in wild baboons

In humans and nonhuman animals, early life adversity can affect an individual’s health, survival, and fertility for many years after the adverse experience. However, whether early life adversity also imposes intergenerational effects on the exposed individual’s offspring is not well understood. Here, we fill this gap by leveraging prospective, longitudinal data on a wild, long-lived primate. We find that juveniles whose mothers experienced early life adversity exhibit high mortality before age 4, and this effect is independent of the juvenile’s own experience of early adversity. Furthermore, our results point towards a strong role for classic parental effects in driving these effects: mothers that experienced early life adversity displayed reduced viability in adulthood, which in turn led to reductions in offspring survival. Importantly, these mothers’ juvenile offspring often preceded them in death by 1 to 2 years, indicating that, for high adversity mothers, the quality of maternal care declines near the end of life. While we cannot exclude direct effects of a parent’s environment on offspring quality (e.g., transgenerational epigenetic changes), our results are most consistent with a classic parental effect, in which the environment experienced by a parent affects its future phenotype and therefore its offspring’s phenotype. Together, our findings demonstrate that adversity experienced by individuals in one generation can have strong effects on the survival of offspring in the next generation, even if those offspring did not themselves experience early adversity.