Early life adversity can shorten baboons’ lives, but strong social bonds can help

Research spanning decades has consistently shown that traumatic experiences during childhood, such as growing up in a tumultuous home or having an alcoholic parent, can have long-term negative impacts on health and survival. However, recent studies indicate that building strong social relationships can help alleviate these effects, not only in humans but also in primates.

A new study conducted over 36 years and involving nearly 200 baboons in southern Kenya reveals that early-life adversity can reduce their lifespan. However, the study also demonstrates that forming robust social bonds with other baboons in adulthood can counteract these negative effects.

The senior author of the study, Susan Alberts, a professor of biology and evolutionary anthropology at Duke University, likened the importance of strong social bonds to the saying from the King James Apocrypha, “a faithful friend is the medicine of life.”

Baboons who faced challenging childhoods were able to regain two years of life expectancy by developing strong friendships.

The findings were published on May 17 in the journal Science Advances.

Previous research has consistently found that individuals who experience more adverse events during their upbringing, such as abuse, neglect, or having a parent with mental illness, are more likely to have a shorter lifespan. However, understanding the precise mechanisms linking these experiences to early death has been challenging.

One limitation of previous research was its reliance on self-reported memories, which can be subjective and imprecise.

This is where long-term studies on wild primates, who share over 90% of our DNA, have provided valuable insights. Researchers have been studying individual baboons near Amboseli National Park in Kenya since 1971, documenting their social interactions and observing their lifespans as part of the Amboseli Baboon Research Project.

In this new study, the researchers aimed to understand how early-life adversity leads to premature death in baboons, even years later. One hypothesis was that trauma survivors often struggle to form healthy relationships as adults, leading to a lack of social support and ultimately reducing their lifespan. However, the findings challenge this hypothesis and offer a different perspective on the causal pathway involved in baboons, offering hope for understanding and intervention.

The study analyzed how early-life experiences and adult social connections influenced the long-term survival of 199 female baboons monitored between 1983 and 2019 in Amboseli. While baboons do not grow up in broken or dysfunctional homes like humans, they do experience various forms of hardship. The research team assessed six potential sources of early adversity for each female baboon, including having a low-ranking or socially isolated mother, maternal death before maturity, being born in a drought year, being born into a large group, or having a close-in-age sibling, which could result in increased competition for resources or maternal attention.

The study revealed that growing up in the challenging and unpredictable landscape of Amboseli, stressful experiences were common for baboons. In fact, 75% of the baboons in the study had experienced at least one stressor, and 33% had encountered two or more.

The analysis confirmed previous findings that a higher tally of hardships during early life led to a shorter lifespan for female baboons. However, this was not solely because baboons who experienced more upheaval were more socially isolated as adults, as Susan Alberts explained.

The researchers determined that 90% of the decrease in survival could be attributed to the direct effects of early adversity rather than weakened social bonds in adulthood.

The cumulative effects were significant. Each additional hardship resulted in a loss of 1.4 years of life, regardless of the strength of their bonds with other baboons. Baboons who experienced four adverse events during their upbringing died almost 5.6 years earlier than those who faced none. Considering that the average female baboon lives up to about 18 years, this is a substantial decrease.

However, having a challenging start in life doesn’t condemn baboons to a prematurely shortened lifespan. Elizabeth Lange, the study’s first author, emphasized that females with difficult early lives are not doomed.

On a positive note, the researchers discovered that baboons who formed stronger social bonds, measured by the frequency of grooming with close friends, added 2.2 years to their lives, regardless of their early-life experiences.

Baboons whose mothers died before they reached maturity but later developed strong friendships in adulthood showed the greatest resilience.

Conversely, weak social bonds can exacerbate the effects of early-life adversity, as noted by Susan Alberts.

While researchers cannot definitively say whether these results are applicable to humans, if they are, it suggests that early intervention is not the sole effective way to overcome the effects of childhood trauma.

Elizabeth Lange highlighted that both early-life adversity and adult social interactions independently impact survival. This implies that interventions throughout the lifespan could improve overall survival.

In essence, focusing on adults and their ability to form and maintain relationships can also be beneficial. As Susan Alberts advised, if individuals have experienced early-life adversity, making friends and cultivating social connections can make a difference.

Source: Duke University

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