Does Social Status Affect Gene Expression?

Dr. Jenny Tung researches immune responses in monkeys

Dr. Jenny Tung received quite the introduction from Reed’s Associate Professor of Biology Dr. Suzy Renn, last Friday, March 26 during the Biology Department’s weekly seminar. 

“I feel like I’ve known about her work forever and then I look and it turns out that she got her Ph.D. in 2010—which is very recent for someone that you feel like you’ve known forever—which just shows that, from the moment she started doing research, those of us in animal behavior were paying attention to what she did,” Renn said. 

Dr. Jenny Tung in her lab. Photo Courtesy of the MacArthur Foundation.

Tung received both her bachelors and doctorate from Duke University, and following the completion of her postdoc at the University of Chicago, she returned to Duke where she now works as an associate professor of biology and evolutionary anthropology. In 2019, Tung was awarded a MacArthur Fellowship, more commonly referred to as the “Genius Grant.”

Tung researches the intersection of social behavior and the genome, an area of anthropology and biology that originated over 100 years ago from research on our own species, but has become increasingly relevant in current national debates about accessibility to healthcare and generational trauma, particularly in relation to the Black community.

At the beginning of her presentation, Tung highlighted four main questions that guide her research: how do social interactions alter genome function; how do social processes change the genetic structure of entire populations rather than just individuals; how might changes in genome function shift social roles; and how might genetic variation shape social behavior? 

Unfortunately, researchers can’t select a randomized group of humans and place them in socially isolated conditions or change their social statuses, so Tung works with rhesus macaque, a species of monkey that share roughly 93% of their genes with humans. They are also listed as “least concern” on the International Union for Conservation of Nature’s Red List of Threatened Species—the world’s most comprehensive information source on the global conservation status of animal, fungi and plant species, according to their website—due to their wide distribution and large populations.

Tung and her team of researchers who hail from Duke University, Emory University, and the University of Chicago, study the monkeys in captivity where it’s possible to take individuals who don’t know each other, and lack any social history, and place them into groups at different intervals, manipulating the order of introduction to the group. Tung and her team found that individuals who entered a group earlier rose to a higher ranking in the group’s social hierarchy. Vice versa, those that entered later had a lower social status. Order of introduction turned out to be the strongest predictor of subsequent dominance rank. 

Tung and her team created multiple groups and allowed the social hierarchies to develop, and then placed all of the alphas in one group, all of the betas in another group, and so forth, allowing new hierarchies to develop. By observing the groups, Tung was able to calculate each individual’s precise hierarchical ranking using the Elo rating system, which is famously utilized to calculate the relative skill levels of chess players.

After the hierarchy of all of the lab’s specimens had been established, the researchers wanted to know how the monkey’s cells would respond to immunological threats and how their social rank might affect their immune function. Because they didn’t want to actually inject immune stimulants directly into the animals, they used a technique used in human studies where researchers draw a blood sample from the individuals and mix the sample with a stimulant and cell culture media to stimulate an acute stress response in the cells. This way they can analyze the gene response in the sample rather than expose all of the animals to this acute stress response. 

The stimulant that they used has two clear downstream pathways which induce two different gene expressions in the cell. They found that the type of gene expression exhibited by an individual depended on their social rank. Cells from low ranking individuals experienced an inflammatory response, whereas high ranking individuals experienced an antiviral immune response.

Tung then went on to research how the history of fluctuations in social status might still impact this gene expression. Her team found that individuals that went from a low rank to a high rank were unaffected by the change in social status, but those that went from high to low status were greatly affected by their new current status. 

The monkeys that Tung and her team were researching are adult specimens that are no longer developing, and yet they still experienced these strong residual history effects, showing that the baggage of social history can affect gene expression up to a year later—that is just how long Tung and her team have researched this set of monkeys.

Tung’s research increases the credibility of social justice arguments and creates more tangible evidence to support efforts to validate generational trauma. Readers interested in learning more about Tung’s research can email Kristy Gonyer for access to all of the biology department’s recorded seminars.