Can Social Rank Impact Human Health? She Says Yes
WHY YOU SHOULD CARE
Because social relationships might literally be our lifelines.
By Viviane Callier
Jenny Tung first traveled to East Africa in 2006 to study the wild baboons of Amboseli, Kenya. She remembers being surprised at how big they were, noting, “They are so human to me.” Tung has returned every year since, adding to decades of detailed field observations about the primates’ social behavior, and bringing cutting-edge genomic tools to bear on the question: Do social relationships have a biological impact on health?
Now an associate professor of biology and evolutionary anthropology at Duke University, Tung is using novel genomic methods to shed light on the biology of how social bonds and social adversity affect our health and long-term survival. And in a world where inequality is ever increasing, her work is catching the attention of social scientists, economists and public policy researchers studying the origins of health disparities — with an eye toward mitigating them.
Tung’s work has brought her into contact with a new population of social scientists, health economists and public policy wonks. And sometimes, things get lost in translation.
In determining how long a person will live, it’s natural to ask: Do they smoke? Exercise regularly? Eat well? But another crucial question, says Tung, is whether someone is lonely or feels integrated. The link between social relationships and health is well known (people living alone have a mortality risk that’s 32 percent higher than those who do not), but it’s been hard to show whether there’s a direct causal connection between the two. For instance, a person who’s lonely might drink alcohol or eat lots of junk food, and the poor diet is destroying their health, not the lack of social interaction. Tung set out to establish whether that causal link between relationships and health exists and, if it does, what biological mechanisms account for it.
Tung, 36, is a second-generation Chinese-American, born and raised in Delaware; her father, a retired chemical engineer, worked with DuPont, and her mother was a teacher before emigrating from Taiwan. Tung was planning a career in medicine until, as a freshman at Duke, she enrolled in a class on biological anthropology. At the end of her sophomore year, she did a research project on the Amboseli baboons with biology professor Susan Alberts, and she got hooked. The project began in 1971 when Jeanne and Stuart Altmann traveled to Kenya to study baboons’ genealogical relationships and social behavior. Tung’s vision was to integrate the Altmanns’ and others’ observational fieldwork with genetic studies. The project formed the basis of Tung’s undergraduate thesis and led to her doctoral work with Alberts and evolutionary genomicist Greg Wray. With a Ph.D. from Duke and a postdoc from the University of Chicago, Tung returned to Duke as a faculty member in 2012.
Four years later, she and her colleagues with the Amboseli Baboon Research Project published a study showing that baboons who experience early life adversity — such as drought, low social rank of the mother, social isolation or loss of the mother — have significantly shorter life spans. In humans, early life adversity also contributes to poor health and a shortened life span, but it isn’t clear whether the cause is lack of access to health care, poor diet, drug use or other negative habits. For Tung, a clear advantage of studying non-human primates is the ability to control for negative health habits. She was thus able to show that the effects of adversity persist even when negative factors are removed, suggesting that adversity does in fact have a direct biological and physiological impact on one’s health and longevity.
Delving even deeper, Tung teamed up with Luis Barreiro, an associate professor at University of Montreal, and Mark Wilson, professor at Emory and researcher at Yerkes National Primate Research Center, to determine if social rank predicts gene activity in immune cells. Using novel genomic methods to study the function of many genes at once, they showed that higher-ranking monkeys had immune cells that dealt differently with a pathogen threat, while lower-ranking monkeys appeared more susceptible to chronic inflammation. What’s more, the researchers found that the effect is reversible: If a low-ranking animal gets moved to a group where it has a higher social rank, that change is reflected in the animal’s immune cells’ improved ability to fight off infections.
Barreiro points out that Tung’s work is unique for “combining the more traditional, classical fieldwork with molecular biology and genomics techniques to get into the biology of what’s happening.” He also praised his partner’s thoroughness and rigor as a scientist, saying she’s been known to triple-check every figure and analysis to ensure accuracy.
But for UCLA psychoneuroimmunologist Steve Cole, an open question remains about the extent to which feelings of loneliness and belonging are similar in humans and non-human primates. “What kinds of feelings and experiences do we need people to have for them to feel like they are securely enmeshed in a social fabric … and that they are not just lone wolves on their own, struggling for survival in a big, harsh, competitive, hostile world?” he asks. “These differences in psychology may or may not pertain to these monkeys, but that’s one of the big questions we need to tackle in future research.”
For Tung, an evolutionary anthropologist attuned to the ways of primates, her work has brought her into contact with a new population of social scientists, health economists and public policy wonks. And sometimes, things get lost in translation. Tung recalls a conversation during her faculty job interview, when she interrupted an economist discussing SES to ask, “What’s SES?” She didn’t recognize the acronym for socioeconomic status, and was mortified. “They should’ve not hired me right then,” she jokes. But even if she’s occasionally pulled away from the lab, she’s excited to see the human relevance of her work brought to the fore — and to contribute to America no longer being a world leader in health inequality.
- Viviane Callier, OZY Author Contact Viviane Callier