Milk is such a homey, familiar substance that it might seem too ordinary to hold any mysteries.

Yet in reality, milk and the act of nursing are extraordinary biological innovations that researchers are still trying to understand.

It's well known that breast milk can help ensure the health of nursing that researchers are still trying to understand.

It's well known that breast milk can help ensure the health of nursing infants, but those benefits aren't simply a result of milk's nutritional content.

Along with being a source of nourishment,

milk also provides protection against germs,

stimulates infant development, and allows mom and baby to

have all sorts of chemical conversations.

Breast milk contains thousands of diverse molecules, including growth factors, hormones,

antibodies and microbes.

All of these work in concert to provide human babies with what they need to grow and develop normally.

But how exactly?

I'm Steve Strogatz and this is The Joy of Why, a podcast from Quantum Magazine, where my co-host, Jan 11 and I take turns exploring some of the biggest unanswered questions in math and science today. In this episode, we'll talk with molecular biologist Elizabeth Johnson about the mysteries of milk

and how we've evolved to be so dependent on this all-powerful, all-natural substance. Liz is an assistant professor of molecular nutrition at Cornell University in the Division

of Nutritional Sciences and a Howard Hughes Medical Institute, Freeman-Rabowski scholar.

She specializes in genomic and metabolomic approaches to studying the effects of nutrition

on the gut microbiome with particular interest in infant nutrition and the infant gut microbiome.

Liz, welcome to the joy of why.

Thank you for having me, Steve.

My pleasure. I'm very happy to see you. I don't think it's exactly relevant, but I can't resist

saying that we're almost next door neighbors. There's one house in between us. Liz is my very good

friend as well as esteemed colleague. Yeah, no, I think that's a good point to me.

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