You've seen the reports that individuals with a lower economic and social status suffer from poor health more often than folks in higher tax brackets. Now, thanks to a multi-year study of rhesus macaques monkeys, researchers have found genetic changes caused by stressful environments are likely contributing to that poor health.
On the bright side, the results also show your genetic fate isn't permanent when you hit a rough patch. We have the power to change our genes as we manage our stress or improve our situation.
Researchers took 49 female macaques out of their family units and placed them in 10 newly constructed groups. They used females because they almost always stay in the same group while males tend to travel. They isolated white blood cells from samples taken from the female monkeys at various points after the transition. They found lower-ranking monkeys had lower levels of a T cell that fights pathogens. They also had high levels of stress hormones in their blood.
The scientists then looked for changes in the monkeys' DNA, and found that their dominance correlated with the presence of "methyl groups", which are things that turn genes on and off.
Jenny Tung, the study's lead author and a visiting assistant professor of evolutionary anthropology at Duke University told me in an email:
Because all the study subjects had been middle ranking in their original groups, we can infer that it was the new dominance ranks they adopted that explained rank-related gene expression. We think that social stress explains these effects because a great deal of research has linked lower rank to increased social stress in captive female macaques (and for primates in some other settings as well), and in fact we were able to measure stress hormone dysregulation in our study subjects indicative of chronic stress.
Tung and her team published their work in the April 9 issue of the Proceedings of the National Academy of Sciences.
The good news is that while rapid genetic changes happened when females found themselves at a lower status, they quickly changed again when their ranks improved. Their immune systems responded quickly when they moved from a lower social rank to a higher one — formerly low-ranking animals looked genetically like high-ranking ones in short time.
So it appears that genetic changes are fluid and definitely not permanent. What does this likely mean for humans? Says Tung:
I think that this study suggests that our physiology — at least as captured by gene expression in our blood cells — may be fairly plastic in response to changes in our social environment. In other words, if you can improve your social environment (or alleviate social stress), your gene expression profile will rapidly reflect that improvement.
Of course all of the work was performed in females. It might remain to me seen whether males could handle stress as efficiently. [Proceedings of the National Academy of Sciences]