Hannah Chinn

So today on the show, the science of biological sex in humans.

So today on the show, the science of biological sex in humans.

So today on the show, the science of biological sex in humans.

You're listening to Shortwave, the science podcast from NPR.

You're listening to Shortwave, the science podcast from NPR.

You're listening to Shortwave, the science podcast from NPR.

OK, Han, so we were just talking about biological sex and how there's like a lot of variation in other animals. But what about humans? Like what's the determining factor for like sex in us?

OK, Han, so we were just talking about biological sex and how there's like a lot of variation in other animals. But what about humans? Like what's the determining factor for like sex in us?

OK, Han, so we were just talking about biological sex and how there's like a lot of variation in other animals. But what about humans? Like what's the determining factor for like sex in us?

I think we need to slow down and like break down each of them. Right. Like so the first one you said is chromosomal. Right. And I remember learning about this in like high school bio. All the genetic information in our bodies are packaged in 46 chromosomes and they're coupled up to make 23 pairs. The first 22 pairs tend to look similar, like, in all humans.

I think we need to slow down and like break down each of them. Right. Like so the first one you said is chromosomal. Right. And I remember learning about this in like high school bio. All the genetic information in our bodies are packaged in 46 chromosomes and they're coupled up to make 23 pairs. The first 22 pairs tend to look similar, like, in all humans.

I think we need to slow down and like break down each of them. Right. Like so the first one you said is chromosomal. Right. And I remember learning about this in like high school bio. All the genetic information in our bodies are packaged in 46 chromosomes and they're coupled up to make 23 pairs. The first 22 pairs tend to look similar, like, in all humans.

But the last one is usually either an XX or an XY pair. And XX is usually assigned to female. XY is assigned to male. Right.

But the last one is usually either an XX or an XY pair. And XX is usually assigned to female. XY is assigned to male. Right.

But the last one is usually either an XX or an XY pair. And XX is usually assigned to female. XY is assigned to male. Right.

Right. And you mentioned a second metric being chemical, right? Like, what do chemicals tell us about sex?

Right. And you mentioned a second metric being chemical, right? Like, what do chemicals tell us about sex?

Right. And you mentioned a second metric being chemical, right? Like, what do chemicals tell us about sex?

Wow. Yep. Yep. So when does this, like, first chemical change actually happen? Puberty?

Wow. Yep. Yep. So when does this, like, first chemical change actually happen? Puberty?