A Difficult Childhood Means a Shorter Lifespan in Baboons
It’s widely known that a tough childhood can lead to a difficult time in adulthood. But for researchers, finding a definitive link is contingent on a multigenerational study of human subjects that would be prohibitively long.
For Jenny Tung and Susan Alberts, wild baboons presented an opportunity to study a population close to our own that can experience psychosocial stress just as we do.
Social creatures, baboons are known to make connections from childhood that last into adulthood. They participate in politics (hierarchies are based not just on biological factors like size and physical power but also social ones like abilities to form alliances) and they compete with one another as well.
For Tung and Alberts, their work with the Amboseli Baboon Research Project presented the right volume of data for a longitudinal study on the subject of early childhood adversity, social connectedness and lifespan.
Tung, assistant professor of evolutionary anthropology and Duke University Population Research Institute (DuPRI) faculty associate, and Alberts, Robert F. Durden professor of biology and DuPRI faculty associate are also assistant director and co-director of the Amboseli Baboon Research Project in Nairobi Kenya.
Initiated in 1971 by co-author Jeanne Altmann of Princeton University, the project has been collecting data from more than 1,500 savannah baboons in east Africa.
“Jean started it in 1971, so it’s a non-human primate equivalent to one of the long-term human population studies in that continuous demographic behavioral data collection has gone on almost everyday since then,” Tung said.
The data was analyzed to determine if experiencing three or more harsh circumstances in childhood would lead to difficulty later in life.
Tung, Alberts and co-authors Altmann and Elizabeth Archie (of the University of Notre Dame) used six different criteria as early life adverse events for the baboons.
These included being born in a drought, having a low ranking or socially isolated mother, having a younger sibling born within 1.5 years and living in a large social group.
What the researchers found was profound. For females who experienced 3 or more of these adverse circumstances, they tended to die 10 years earlier than females did not experience any.
Of females who reach adulthood, the average lifespan is about 18.5 years, so 10 years difference is an incredible result, Alberts said.
The researchers also found that females who experience early life adversity tend to be more socially isolated even in adulthood.
“We wanted to see whether social connectedness predicted survival in baboons. And we found that it did. And what we found was fairly striking,” Alberts said.
Female who were relatively well connected socially lived about two years longer than females who were more socially isolated. Two years is enough time for additional offspring, and approximate to about six years of a human life.
The results offer a powerful link between childhood adversity and mortality using a simpler social model.
“When you pick up parallels like the ones we’re talking about in this study, it suggests there’s something fundamentally biological about the relationship between early life adversity and later life health and survival that can’t be explained by differences in health habits and access to health care,” Tung concluded.
The study appears in the journal Nature Communications and can be found here.