Welcome to Quantum Magazine's podcast.

Each episode, we bring you stories about developments in science and mathematics.

I'm Susan Vallett.

Our bodies consist of about 30 trillion human cells, but they also host about 39 trillion microbial cells. These teeming communities of

bacteria, viruses, protozoa, and fungi in our guts, in our mouths, on our skin, and elsewhere,

are collectively called the human microbiome. But they don't only consist of freeloaders and lurking pathogens. Instead,

as scientists increasingly appreciate, these microbes form ecosystems essential to our health.

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A growing body of research aims to understand how disruptions of the human microbiome can rob us of nutrients we need,

interfere with the digestion of our food, and possibly trigger afflictions of our bodies and minds.

But we still know so little about our microbiome that we're just starting to

answer a much more fundamental question. Where do these microbes come from? Can they spread from

other people like a cold virus or a stomach bug? Now the largest and most comprehensive analysis

of human microbiome transmission has provided some important clues.

Genomicists at the University of Trento in Italy have found hints that microbiome organisms hop extensively between people,

especially among those who spend a lot of time together. Their findings were published

in January of this year in nature. They fill important gaps in our understanding of how people

assemble their microbiomes and reformulate them throughout their lives. Other scientists have applauded

the study. Jose Clemente Littron, an associate professor of

genetics and genomic sciences at the Ican School of Medicine at Mount Sinai, calls the work

...