Close, Social Contact Can Shape a Gut Microbiome, Sometimes Making it More Alike
Our gut microbiome plays a major role in our health, and fortunately, we have no shortage of tips for taking care of it. Most recommendations focus on diet, such as prioritizing foods high in fiber and probiotics, as well as lifestyle adjustments such as getting enough sleep and managing stress.
But we may need to add one more factor to the list: the people we spend time with. It turns out that our loved ones can influence our internal microbial world in subtle but significant ways. A new study from the University of East Anglia (UEA) explores this idea by analyzing the gut bacteria of Seychelles warblers, a small songbird living on a remote island, the perfect natural laboratory.
Previous human studies have hinted at this effect, showing that spouses and roommates tend to share more similar gut microbiomes than strangers. However, this study on birds, published in Molecular ecologyprovides clearer evidence that social proximity beyond shared environments can shape microbiome composition.
“Whether you live with a partner, roommate or family, your daily interactions – from hugs and kisses to sharing food preparation spaces – can encourage the exchange of gut microbes,” said study first author Chuen Zhang Lee, a researcher in the UEA School of Biological Sciences, in a statement.
Social connections and gut microbes
To investigate, researchers traveled to Cousin Island in the Seychelles, home to Acrocephalus sechellensisa warbler known for its unusual cooperative breeding behavior. In this system, unrelated birds help breeding pairs raise their young. By collecting fecal samples over several years, the team sought to understand how proximity and social interaction influence birds’ gut microbiomes.
“We collected hundreds of samples from birds with known social roles – breeding pairs, helpers and non-helpers living in the same group and in different groups,” Lee said. “This allowed us to compare the gut bacteria of birds that interacted closely at the nest with those that did not.”
The researchers focused on anaerobic bacteria, microbes that do not need oxygen to survive. These bacteria are particularly useful for this type of study because they typically spread through direct, close contact rather than through the environment, making them an ideal marker for demonstrating “how social connections can promote the transmission of gut microbes,” according to Lee.
Anaerobes also play an important role in digestion and immunity, forming long-term stable communities once established in the intestine.
Learn more: Bird droppings helped fuel one of ancient Peru’s richest kingdoms
An island that serves as a laboratory
The results showed a clear trend: the closer the birds were socially, the more anaerobic bacteria they shared. This was true for breeding pairs as well as their unrelated helpers.
“These anaerobic microbes cannot survive in the open air, so they do not drift into the environment,” Lee explained. “Instead, they move between individuals via intimate interactions and shared nests.”
Cousin Island makes this type of research possible in a way few places can. The entire warbler population has been closely monitored for years, with detailed records of its behavior, genetics and health.
“This gives us the best of both worlds,” David Richardson, co-author of the study, said in the press release. “We can study animals living natural lives, with natural diets and gut bacteria, while still being able to collect detailed data from known individuals.”
What birds can tell us about our own microbes
But what do the birds of a remote island have to do with us? According to researchers, that’s a lot, especially if you share living space with others. Although human and avian microbiomes are not identical, the underlying dynamics are similar enough to draw meaningful parallels.
“The people you live with can subtly shape the microscopic ecosystem inside you,” Lee added. “Translated into human terms, this means that [cozy] Stay-at-home nights, shared dishwashing chores, and even sitting by the couch can quietly bring your microbiomes together. Sharing beneficial anaerobic bacteria could boost immunity and improve digestive health within a household.
This article does not offer medical advice and should be used for informational purposes only.
Learn more: What to do – and what not to do – to keep your gut microbiome healthy
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