You're listening to 20,000 Hertz.

The stories behind the world's most recognizable and interesting sounds.

I'm Dallas Taylor.

Shh, shh, mommy's here.

We're all natural-born criers.

It's the most basic form of communication from right when we come into the world.

That's producer Katie Daily.

When we're babies, we cry when we're hungry.

And when we're in pain.

It's the easiest way to communicate that something's wrong and to get the help we need.

For many animals, it's actually built into the parents' brains to react immediately to the sound of their infant's cries.

The parent might even see or smell the infant in distress, but it's that sound that kicks them into gear.

Crying has to be loud enough to attract the parent, which unfortunately means it's loud enough to attract predators as well.

So most animals, when they're old enough to fend for themselves, have evolved to grow out of crying entirely.

Not humans.

We keep on crying for the rest of our lives.

Now, it's more likely to be because of a bad breakup than an empty stomach as we go from crying

for necessity to crying emotionally.

But if we don't need to signal for that critical help anymore, what's the purpose of crying

when we're emotional?

First, let's talk about our wiring.

An infant's cry triggers an immediate response by caregivers.

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