As well as being good for our mental health, it seems that having plenty of friends can be good for the health of our gut, a new study says.

Scientists looked at a group of Rhesus Macaques living on Cayo Santiago, an island off the coast of Puerto Rico, and found that the more sociable primate had more beneficial bacteria and less harmful bacteria than less social monkeys.

To measure just how social the monkeys were, the researchers measured the time each monkey spent grooming or being groomed by others, as well as the number of grooming partners they had.

“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,” Dr Kali Watson, a cognitive scientist at the University of Colorado, said.

They also collected faecal samples from the monkeys and performed DNA sequencing to measure the composition and diversity of gut microbes that were present.

“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,” Dr Philip Burnet, who researches the influence of the gut microbiome on brain health at the University of Oxford, said.

They found that the most sociable monkeys had higher levels of protective bacteria, including Faecalibacterium, which has anti-inflammatory properties, and Prevotella, which has been associated with better immunity against pathogens and anti-inflammatory effects.

Meanwhile, bacteria such as Streptococcus, which cause diseases such as strep throat and pneumonia, were found in greater abundance in the less social monkeys.

Image: Frontiers Press

As for why this happens, the researchers proposed that it may be to do with the transmission of bacteria through physical contact, such as grooming.

“The relationship between social behaviour and microbial abundances may be the direct result of social transmission of microbes, for example through grooming,” Dr Katerina Johnson, a researcher at the University of Oxford, said.

“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 behaviour influencing the microbiome, we also know it is a reciprocal relationship, whereby the microbiome can in turn affect the brain and behaviour.”

The millions of bacteria, fungi and other microorganisms that live in our gut – and make up our gut microbiome – have become an area of interest for researchers, particularly when it comes to digestive health and the influence it has on our nervous system, in a relationship called the ‘gut-brain axis’.

Previous studies have shown that the levels of different species of these organisms in our guts have been linked to depression, schizophrenia and even autoimmune conditions such as Crohn’s disease and colitis. The gut even creates neurotransmitters, hormones and other molecules the brain needs.

With this study finding that being social can influence our gut, which in turn can influence our health more generally, it shows just how crucial social interactions are for our health.

Dr Robin Dunbar, a psychology professor at the University of Oxford, said: “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.”

The researchers published their findings in the journal Frontiers in Microbiology.

Image: Frontiers Press

This article first appeared on OverSixty.