Scientists have found that social status affects the immune systems of rhesus macaque monkeys. Macaques at the bottom of the social hierarchy have different immune responses than macaques with high social standing. The details are in a paper that was just published in the journal Science.
Humans with low socioeconomic status tend to have shorter lifespans and high rates of inflammatory diseases such as diabetes and cardiovascular disease. This has generally been attributed to poor nutrition, lack of proper exercise, and other lifestyle differences. However, past animal studies have provided evidence of a molecular mechanism related to social status, possibly explaining the health disparity between different socioeconomic groups.
A research team studied rhesus macaques (Macaca mulatta) at the Yerkes National Primate Research Center. The team placed unrelated macaques in an enclosure to let them form a new group. The group consisted of 45 individual females that had never met each other. The macaques that were added to the enclosure first became higher ranked while the last monkeys ended up at the bottom of the social hierarchy. The team analyzed immune cell samples and found that over 1,600 genes were expressed differently between high and low ranking monkeys. When the macaques’ blood cells were exposed to a bacterial toxin, the cells from lower ranking females had a more dramatic immune response, leading to increased inflammation.
The team then moved the macaques around and created new groups. Females that had previously been low ranked were now at the top of the hierarchy. Interestingly, the next set of samples showed that the change in social rank was enough to change the immune response. The females that had previously been at the bottom of the hierarchy now had improved immune systems with less exaggerated responses to pathogens. This shows that while social status can affect the immune system, the changes are reversible when rankings are adjusted.
The team’s findings may help researchers better understand the health disparity between humans of different socioeconomic classes. The authors are hopeful that improving the social standing of disadvantaged people could improve their overall health.
Snyder-Mackler et al. Social status alters immune regulation and response to infection in macaques. Science (2016).