You're listening to Shortwave from NPR.

Shortwavers, I'm going to take us back to high school biology, the genetics chapter.

You may have learned that the human body is made up of trillions of cells, and inside those cells are DNA molecules, those strands that contain the genetic code that makes you, you. But here's something

that may surprise you and you may not have learned in school. That DNA is not the same for every

cell. And that's because DNA is constantly changing. There's actually trillions of mutations

happening in your cells every day. This is Roxanne Comsi. She's a science journalist and a contributing writer at The Atlantic.

We're just constantly in flux, partly because there's just wear and tear, like genes will get

turned on and sometimes things will break, and then enzymes will come in and try to fix it,

but they won't always do the best job fixing it. So we are kind of a landscape of

genetic diversity, each of us, just by nature of all the DNA changes, all those errors that

pile up over the course of our lives. By the way, scientists have known for decades that our genes

mutate. It's just that in the last decade, DNA sequencing has gotten so much more powerful and precise.

The scientists can now read the genetic code of individual cells.

There's been this possibility to kind of do a census of the cells in a body

and figure out which ones have which mutations that the other cells don't have.

So then here we are, grasping this diversity,

this genetic diversity that exists inside us. And it turns out there is a lot of genetic diversity

going on inside us, so much so that Roxanne wrote an entire book about it called Beyond Inheritance

are ever mutating cells and a new understanding of health.

People hear the word mutation, and they immediately think about something negative,

but there's also good things that can happen with mutation.

So today on the show, genetic mutations, like you've never seen them before.

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