Being social may be good for your gut

Your friend circle may share more than just secrets. Social life diversifies the composition of microbes living in the gut, according to new study of chimpanzees. If this primate pattern holds true in humans, then your tummy and health may get by with a little help from your friends.

“The more diverse people’s microbiomes are, the more resistant they seem to be to opportunistic infections,” University of California integrative biologist and study co-author Andrew Moeller said in a statement.

Germ swapping between animals isn’t new. Humans and their dogs share skin microbes. Baboon tribes can be identified by their gut microbiomes — the collective germ population in their stomachs. And people walk the Earth immersed in a cloud of skin and fart bacteria, so it’s easy to imagine the intermingling of bacteria between individuals.

These microbial meetups shape the gut for generations, according to Moeller’s new findings.

He and colleagues at Duke University and University of Texas at Austin spent eight years tracking 40 Kasekela chimpanzees living in Gombe National Park in Tanzania. During the dry seasons, the chimps are solitary or forage in small groups, but when the rainy season hits, they form larger social networks to find food.

To monitor the gut health of the primates, the researchers monitored the chimps throughout the wet and dry seasons. The scientists would wait for the chimps to “use the bathroom” and then collect a fecal sample. The team also conducted DNA analysis to make sure the samples consistently came from the same individuals.

They found that when chimps became more social during the wet season, the microbiomes of individual chimps began to resemble each other. Diet can alter the gut microbiome, so you might think that this convergence happened because the social groups were more likely to share food. But diet didn’t correlate with the makeup of microbes in these chimps.

This result suggested the similarities in stomachs depended on the fraternity and sorority of the chimps. Moreover, chimps with richer social lives had a richer composition or diversity of gut microbes, which may be good for their immune systems, though the study didn’t examine this point.

One more thing: newborn chimpanzees seem to inherit the social community of germs. Both baby chimps and baby humans inherit gut microbes from their mothers. But Moeller and company found that germ communities were similar between kin and unrelated individuals.

This inheritance of social structure may be the key to maintaining the gut health of chimpanzees as a species, the authors write in their study in Science Advances, though further research is needed to see how these trends apply to humans.