From the brains behind brains on, this is the Moment of Um.

Um, Um, Um, Um, Um, Um, Um, Um, Um, Um.

Moment of Um comes to you from APM Studios. I'm Molly Bloom.

Um.

Growing up, I remember being around the same height as all the other kids.

I could easily give them high fives, look them right in the eye,

look out into the world, and see the same objects they did. But then something weird happened.

They kept getting taller and taller, but I sort of slowed down while they seemed to speed up.

As a full grown-up, I stand at five foot one inches tall. Some may call that short, but I call it

just right. It does have me wondering, though, how do our bodies decide when they're done growing?

Why don't we just grow taller and taller? If anything, we seem to shrink a bit over time.

Listener, Amelia, was thinking about all of this this and now I'm thinking about all of this.

Hi, my name's Amelia and I'm from Bothwell, Washington. And my question is, why do we stop growing taller in some point in our lives?

Shrinking is probably a little easier to explain because you actually lose bone mineral mass over time.

So as you start out life, the amount of calcium in your bones gradually increases until you're about 25.

And then when you're about 35, you start losing about 1% of the calcium every year.

And those bones get weaker, and so gravity exerts their

force on them, and they collapse a little bit. Not a big time collapse for just a little bit.

This is Frank Rame. I'm an infectious diseases physician at Lina Health. So the question about

why you stop growing is actually a much more difficult question.

It really goes back to evolution.

Each creature, each species has to exploit a particular environment to get energy and to avoid predators.

...