The microbiome, the network of tens of trillions of microbes that live in and on our bodies, helps us digest food and protects us from diseases. And depending on what species of bacteria you have, your microbiome could impact your stress response, decision-making, and how likely you are to develop arthritis and depression.

Scientists have known that your microbiome is partially shaped by your environment, and the people you spend your time with. But they haven’t had a lot of clarity on how exactly social networks outside of home and family impact our microbiome makeup.

To learn more, a team from Yale University mapped the connections among 2,000 people in isolated villages in Honduras and compared their microbiomes to see how exactly their social closeness impacted their gut bacteria. And it turns out, we’re more connected to people in our lives than you may think. Their research was published in the journal Nature.

Ira Flatow is joined by sociologist and physician Dr. Nicholas Christakis, who directs the Human Nature Lab at Yale University. He studies the biology of human social interactions and was an author on the recent paper. They discuss how the researchers worked with villages in Honduras to gather samples and how they can tell who your friends are, just by looking at your poop.

Transcripts for each segment will be available after the show airs on sciencefriday.com.

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