London: Bullying doesn`t just hurt one`s feelings -- it can damage one`s immune system also, according to researchers who have based their findings on a study on monkeys.
Lead author Jenny Tung at Duke University studied rhesus macaques and found that when one was introduced to a new group, which results in it having the lowest status, it
became stressed and its immune system dropped in efficiency.
The researchers believe that the social stress that moulds a monkey`s immune system could help understand how stress affects humans, the `Daily Mail` reported.
In fact, they studied 10 groups of female macaques in which researchers could manipulate individuals` social rank. Before being placed into new groups, all of the macaques started out as middle rank.
"In the wild, macaques inherit their social rank from their mothers. But in our research, the order of introduction determines rank. The newcomer is generally lower status. When
some macaques` status changed after a newcomer arrived, so did their patterns of immune system gene activity," Tung said.
The researchers used microarrays, a technology that allows them to scan thousands of genes and read the expression levels, to look at the macaques` immune cells. The gene
activity that changed the most depending on social rank was
what controlled inflammation.
Previous studies have found lower status macaques have higher levels of inflammation and have changes in their levels of hormones that indicate they`re under more stress.
Based on the pattern of gene activity, the researchers could, without looking at a monkey`s identity, predict whether that animal was high (rank one or two), middle or low (rank four or five) with 80 per cent accuracy.
Seven monkeys` social ranks changed because other individuals were moved. When this happened, the researchers were able to take blood samples before and after the shift.
The gene scans revealed the pattern of immune system activity changed along with these monkeys` social ranks. Here, social rank post-shift could be predicted to 86 per cent accuracy (six out of seven).
"There`s a concerning side to this kind of research, in that an individual`s social environment probably partially determines health status," Tung said.
Another researcher Dr Mark Wilson added: "But there`s also a hopeful side. For the seven females that changed ranks, their gene status changed with them. That they are not stuck
in place says something more broadly about the capacity for change within human society."