Strong adult social relationships may mitigate some negative effects of early life adversity in wild primates
Adversity in early life and poor social relationships as an adult are both linked to shorter lifespans in wild primates, according to the results of an NIA-funded study reported in Science Advances. Scientists found that having strong social relationships in adulthood could buffer the negative impact of early life adversity on survival. The findings suggest that actions to improve social relationships in both early childhood and adulthood could effectively increase healthspan in humans.
Harsh conditions in early life are associated with shorter lifespan in humans, wild primates, and other mammals. Scientists are still exploring the reasons behind this link. Some researchers hypothesize that early life adversity leads to weak social relationships as an adult, which in turn reduces lifespan. Although previous studies have linked poor social relationships in adulthood to reduced lifespan, the extent to which poor social relationships explain the effects of early life adversity on lifespan is not clear. In this study, an international research team led by Duke University scientists analyzed data from wild primates to explore how early life adversity, adult social relationships, and lifespan are related.
The researchers analyzed data from 199 female baboons from the Amboseli ecosystem in Kenya. This study population of wild primates has been under continuous observation on a near daily basis since 1971, enabling researchers to track the individual trajectories of each animal across the lifespan. The scientists considered several sources of early-life adversity, including drought in the first year of life, death of the mother before age 4, and having a close-in-age younger sibling. In addition, the researchers used grooming interactions to estimate the strength of each female’s social bonds with adult males and other females.
The scientists found each additional source of early life adversity shortened lifespan by an average of 1.4 years, regardless of the strength of adult relationships, and the effect was cumulative. For example, baboons that experienced four sources of early life adversity were predicted to have a lifespan 5.6 years shorter on average than primates that had no early life adversity. The researchers also found that having strong social bonds could improve the chances of survival for baboons that were exposed to certain types of early adversity. Baboons that formed strong social relationships in adulthood, measured by how often they groomed with their closest companions, extended their lives by an average of 2.2 years, no matter what hardships they experienced in early life. These findings suggest that social relationships and early life adversity affect lifespan independently of each other.
Overall, results suggest that strong social relationships in adulthood may mitigate some of the negative consequences of adverse early life events on survival in wild primates. Additionally, the study shows that poor social relationships in adulthood do not explain the link between early life adversity and reduced lifespan. The study authors recommend further research to examine biological factors, such as changes in the immune system and hormones, as possible links between adverse childhood events and survival as an adult.
Reference: Lange EC, et al. Early life adversity and adult social relationships have independent effects on survival in a wild primate. Science Advances. 2023. Epub May 17. doi: 10.1126/sciadv.ade7172.