Understanding the human body is a team effort. That's where the Yachtel group comes in.

Researchers at Yachtolt have been delving into the secrets of probiotics for 90 years.

Yachtold also partners with nature portfolio to advance gut microbiome science through the global grants for gut health, an investigator-led research program.

To learn more about Yachtolt, visit yacolp.co.

That's Y-A-K-U-L-T dot CO.JP. When it comes to a guide for your gut, count on Yacol.

There have been a lot of headlines in recent years about transgender athletes.

But this isn't actually the first time debates over biological sex have caused controversy and exclusion in the sports world.

Even athletes who identify with the sex they were assigned at birth, meaning people with XX chromosomes who were assigned female at birth and identify as

women today can find themselves banned from elite competition on the basis of their biology.

For Scientific American Science quickly, I'm Rachel Fultman. Today I'm talking to award-winning

reporter and writer Rose Avaleth. They're the creator and host of a new series

called Tested, co-produced by CBC podcasts and NPR's Embedded. Tested follows the surprising 100-year

history of sex testing in elite sports, which has culminated in some shocking modern policies.

So, Rose, for listeners who aren't familiar with your work, I would love to hear a little bit

more about how you came to this story.

I was an intern in the ye oldy days of Scientific American.

As was I.

What a time.

Yeah, in the blog minds of the early science internet. But so I was an intern What a time. Yeah, in the blog minds of early science internet.

But so I was an intern at Scientific American and I was looking for something to write about.

And I had been writing a lot about prosthetics because, you know, when you're an intern, you say yes to literally anything anyone gives you to write.

And as I was looking for something to write about, I came across the story of Oscar

...