A November 2022 study of macaques by the Department of Experimental Psychology and the Department of Psychiatry of the University of Oxford, said:
“Here we show that more sociable monkeys have a higher abundance of beneficial gut bacteria, and a lower abundance of potentially disease-causing bacteria.”
“Macaques are highly social animals and grooming is their main way of making and maintaining relationships, so grooming provides a good indicator of social interactions.”
“Engagement in social interactions was positively related to the abundance of certain gut microbes with beneficial immunological functions, and negatively related to the abundance of potentially pathogenic members of the microbiota,”
“It is particularly striking that we find a strong positive relationship between the abundance of the gut microbe Faecalibacterium and how sociable the animals are. Faecalibacterium is well known for its potent anti-inflammatory properties and is associated with good health,”
“The relationship between social behavior and microbial abundances may be the direct result of social transmission of microbes, for example through grooming. It could also be an indirect effect, as monkeys with fewer friends may be more stressed, which then affects the abundance of these microbes. As well as behavior influencing the microbiome, we also know it is a reciprocal relationship, whereby the microbiome can in turn affect the brain and behavior,”
“As our society is increasingly substituting online interactions for real-life ones, these important research findings underline the fact that as primates, we evolved not only in a social world but a microbial one as well.”