You might share a lot of things with your friends, but it turns out that you also share each other's microbiomes.

We show that we could predict your friends based on your poop. It's Thursday, December 12th, and you're listening to Science Friday.

I'm Cyfry producer, D. Peter Schmidt. The microbiome is a super complex network made up of trillions

of microbes that live inside and on our bodies. It helps us digest food, protects us from diseases,

and depending on what species of bacteria you have, your microbiome could impact how likely you are

to develop arthritis and depression. Scientists know that your microbiome is partially shaped by your environment and the people

you spend time with, but they haven't had a lot of clarity on how exactly your social

networks outside of your home and family impact your microbiome makeup.

But new research shows that we're more connected to our friends than you may think.

Here's Ira Flato with more.

To learn more, my next guest and his team mapped close to

2,000 social connections in isolated villages and compared their microbiomes to see just how

exactly their social closeness impacted their gut bacteria. Their research was published in the

journal Nature. Here to tell us more is Dr. Nicholas Christakis,

a sociologist and physician at Yale University where he directs the human nature lab.

He studies the biology of human social interactions and was an author on that research.

Welcome back to Science Friday. Thank you so much for having me back, Ira.

Nice to have you back.

What were the big questions you wanted to answer in this study?

Well, overall, we wanted to understand where does the microbiome in our bodies, in our guts in particular, come from.

You know, these bacteria are optimized to live in the anaerobic environment inside our intestines.

They don't really survive very long outside our bodies.

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