Living with other people may quietly change the tiny organisms that live in our stomachs. Scientists at the University of East Anglia discovered this by watching a small bird on a tiny island.
The bird, called the Seychelles warbler, lives on Cousin Island. Researchers collected many pieces of bird poop over several years. By looking at the poop, they could see which bacteria lived inside each bird.
They found that birds who spent a lot of time together—like a breeding pair or a helper bird that helps raise chicks—had very similar bacteria. The similarity was strongest for bacteria that cannot survive in open air and need an oxygen‑free place, called anaerobic microbes.
Because the island is small and isolated, every bird could be marked with a colored ring. This let scientists follow each bird’s life, behavior, and health, almost like a lab experiment that still happens in nature.
“When two birds live side by side in the same nest, they pass bacteria directly to each other,” explained Dr. Chuen Zhang Lee, who led the study. “These microbes don’t float around the environment; they need close contact to move.”
What does this mean for people? The same idea may happen in our homes. Hugging, sharing a kitchen, or even sitting close on the couch could let us swap helpful bacteria with family members or roommates.
Important bacteria that help us digest food and fight germs often live without oxygen. When we share these microbes, we might boost each other's immune systems and keep our digestion smooth.
The study involved scientists from several universities and research institutes. Their findings were published in the journal Molecular Ecology under the title “Social structure and interactions differentially shape aerotolerant and anaerobic gut microbiomes in a cooperative breeding species.”