Researchers studying wild baboons reveal that harsh circumstances during childhood can have negative affects on their health and survival as adults. The findings, published in Nature Communications this week, resemble the effects that poor medical care and risky behavior like smoking can have in humans.
Adverse conditions early in life are thought to have far-reaching implications. In humans, previous studies have linked early adversity – ranging from child abuse to famine – with cardiovascular disease, schizophrenia, and type II diabetes risk well into adulthood. But the roots of these effects likely date all the way back to our early evolutionary history.
Duke University’s Jenny Tung and colleagues studied data on 196 female baboons (Papio cynocephalus) living in the Amboseli basin of southern Kenya from 1983 to 2013. The area has been home to about 1,700 animals since the early 1980s, with between 250 to 350 baboons at any given time. The team focused on six potential sources of misfortune during the first four years of the baboons’ lives: drought, overcrowding, competition among siblings, losing a mother, and having a mother with a low social rank or with few connections to other females.
More than three-fourths of the baboons faced at least one of the six early risk factors, and 15 percent suffered three or more. The most vulnerable among them were baboons who lost their mothers before they were four years old, and those whose siblings were born before they were fully weaned.
In fact, cumulative early adversity can predict lifespan: Females who lived through three or more sources of early adversity die 10 years earlier than females who experienced no more than one adverse circumstance. Additionally, females who experience the most adversity became more socially isolated adults.
With the median lifespan of wild baboons at 18.5 years, that means "silver spoon kids" lived into their late teens and early twenties, whereas the "bad luck babies" died by the time they were nine. Not only did they lose a decade off their adult lives, they also had fewer surviving offspring. As study co-author Elizabeth Archie from the University of Notre Dame described in a statement: "It's like a snowball effect."