A new study in PNAS on rhesus macaques shows that a change in their social status leads to epigenetic changes that affect their health, reports Nature News' Zoë Corbyn. A Duke University team studied 49 captive female rhesus macaques all originally with a medium social rank, and then divided them into groups where their ranks changed. The lower the rank, the more stress the monkey experienced, as a low rank meant less access to resources, Corbyn says. Then the researchers analyzed blood samples from the monkeys. "Of the 6,097 genes tested, 987 showed significant changes in expression level, associated with rank," she adds. "The researchers could predict whether an animal was high, middle, or low ranking with 80 percent accuracy, on the basis of gene expression alone." The lower the monkey on the social ladder, the worse its health was, the researchers found — the immune systems of lower-ranked monkey was more active, particularly the genes linked to inflammation, creating more wear on their bodies.
However, that state was not permanent, Corbyn says, and the animals' gene expression changed to match their social status as it changed. "The findings … could help to explain why low socioeconomic or professional status is associated with poor health in humans," Corbyn adds.