Early life adversity and adult social relationships have independent effects on survival in a wild animal model of aging

Abstract

Does social isolation in adulthood predict survival because socially isolated individuals are already unhealthy due to adversity earlier in life ("health selection")? Or do adult social environments directly cause poor health and increased mortality risk ("social causation")? These alternative hypotheses are difficult to disentangle in humans because prospective data on survival and the environment for both early life and adulthood are rarely available. Using data from the baboon population of Amboseli, Kenya, a model for human behavior and aging, we show that early adversity and adult social isolation contribute independently to reduced adult survival, in support of both health selection and social causation. Further, strong social bonds and high social status can buffer some negative effects of early adversity on survival. These results support a growing change in perspective, away from "either-or" hypotheses and towards a multi-causal perspective that points to multiple opportunities to mitigate the effects of social adversity.

Early life adversity has sex-dependent effects on survival across the lifespan in rhesus macaques

“…Early life adversity in female baboons (Papio sp.) is associated with reduced fecundity and poorer offspring survival (Lange et al, 2023;Lea et al, 2015;Patterson et al, 2021;Tung et al, 2016Tung et al, , 2023Weibel et al, 2020;Zipple et al, 2019). Organisms are hypothesized to adjust their developmental trajectories in response to early life adversity in order to improve immediate survival (Lea et al, 2017;Lea & Rosenbaum, 2020;Patterson, Petersen et al, 2023), but such adjustments may lead to these detrimental outcomes in adulthood.…”

“…Females who live longer have a longer reproductive span, and are able to produce more offspring. Long-term studies have shown that early life adversity is associated with reduced survival in adult female baboons and hyenas (Crocuta crocuta) (Gicquel et al, 2022;Lange et al, 2023;Strauss et al, 2020;Tung et al, 2016). In populations characterized by high mortality rates prior to reproductive maturity, LRS based on the total number of offspring reaching reproductive maturity is the best proxy for fitness (e.g., Alif et al 2022).…”

Advancing methods for the biodemography of aging within social contexts

“…Several mammal species have shown increased mortality risk in highly connected individuals (Blumstein et al, 2018;Thompson and Cords, 2018), in cooperatively breeding species versus non-cooperative ones (Vágási et al, 2021) and in individuals lacking social support (Begall et al, 2021), suggesting that benefits from social relations may not be universal across species (Blumstein et al, 2018). Together, these patterns highlight further the need for a foundational eco-evolutionary methodological framework to study health and aging within social contexts (Lange et al, 2022).…”

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

“…Notably, emerging work suggests that the quality of an individual's future environment may buffer against, or magnify, the costs of harsh early-life environments. In non-human primates, an individual's social environment predicts longevity [33], and strong social bonds and high social status during adulthood can ameliorate the negative effects of early-life adversity on survival [34]. Beyond sociality, future food availability may similarly modify the long-term effects of early-life adversity, particularly in less social species.…”