The link between a difficult childhood and difficult adulthood is a well-documented one: Research has shown time and time again that people who deal with trauma or ongoing struggle early in life — things like abuse, poverty, or the death of a parent — are at greater risk for a host of health problems down the line.
But new research suggests that the pattern may not be unique to humans: In a study published earlier this week in Nature Communications, a team of biologists found that baboons, too, can suffer the effects of a tough childhood well into their later years.
Specifically, they focused on six sources of adversity: drought during the first year of life; being born into a large social group, which means more competition for resources; a mother with a low dominance ranking within the group hierarchy; a mother with few social connections; death of the mother before the baboon reached adulthood; and a younger sibling close in age, which may divert the mother’s attention. (Note that all of these things can also be loosely translated into human problems — low socioeconomic status, family tragedy, neglect.)
Within the population they studied, 43 of the baboons had relatively easy lives, experiencing none of the hardships the researchers were tracking, and 72 had to deal with just one (the researchers called these two groups the “silver spoon kids”). On the other end of the spectrum, 29 experienced three or more.
Even after the members of this last group left the trauma behind, the researchers found, the effects followed them into adulthood: The unluckiest baboons had an average life expectancy ten years shorter than that of their more fortunate peers, living for an average of nine years while others died in their teens or 20s. They also had fewer surviving kids of their own, and tended to have fewer social bonds, even after the researchers controlled for other factors that influence connectedness, like age and dominance. (A separate 2014 study of the Amboseli baboons found that social connectedness is linked to a longer lifespan).
The notable thing about the baboon-human parallel here is that studying the connection between baboons’ childhood experiences and adult health may help us understand how the same process plays out in our own bodies. In humans, this line of research is often complicated by other lifestyle factors — access to healthcare, for example, or differences in diet and exercise, or substance abuse — that baboons just don’t have. Researchers also have the added advantage of being able to monitor the baboons’ lives to a greater extent than they would with people. In the future, studies like this one might help researchers to fill in the gaps in human research — and to better understand why we, like our primate cousins, can’t seem to fully shake the ghosts of our past.