The researchers also found that less sociable monkeys had a higher abundance of Streptococcus bacteria, a group that includes harmful bacteria. It is interesting that our findings reflect this at the level of the gut microbiome. Since the gut microbiome regulates the immune response, our microbes may play a role in this link between our social lives and health.' This relationship between social behaviour and microbial abundances may be the direct result of social transmission of microbes. It could also be an indirect effect as monkeys with fewer friends may be more stressed which then affects the abundance of these microbes.