Higher ranking of a female monkey within her troop can alter the functioning of almost 1,000 genes within a matter of few weeks, also improving their immune system, says a new study.
"We were able to use gene expression to classify individuals based on their rank," said study co-author Yoav Gilad, associate professor of human genetics at the University of Chicago Biological Sciences.
The research, led by Chicago postdoctoral researcher Jenny Tung, was conducted with rhesus macaques housed in groups of five at the Yerkes National Primate Research Centre, Atlanta, reports the journal Proceedings of the National Academy of Sciences.
As in the wild, each group self-organises into a dominance hierarchy, defined by which individual yields first during competition over food, water and grooming partners, according to a Chicago statement.
In captivity, dominance is determined by the order of introduction into the group, giving researchers an opportunity to study how changes in rank lead to biological effect.
"In the wild, females would not ordinarily leave the social group they were born into," said Tung, now assistant professor of evolutionary anthropology at Duke University.
"They inherit their social rank from their mothers. But in this unnatural situation, order of introduction determines rank -- the newcomer is generally lower status."
Previous research on rhesus macaques discovered that social rank influenced components of the stress response, brain and immune system.
With gene chip technology for measuring the expression of over 6,000 different genes, Tung, Gilad and colleagues at Yerkes, Emory University and Johns Hopkins looked for the first time in primates at the effects of social rank on genetic function.
Comparing 49 different female monkeys of different rank revealed significant changes in the expression of 987 genes, including 112 genes associated with immune system function.