You're listening to Shortwave from NPR.

So, John, I can tell that the warm weather is arrived because I woke up this morning to

like a small swarm of fruit flies in my kitchen and I just like I couldn't sweat them fast

enough.

I was, stop right there.

What?

I am here today to tell you how these tiny critters you're talking about how they can teach

us something important about mental health conditions like post-traumatic stress disorders.

Whoa, what? Are you highly evolved brainguides saying that fruit flies actually get PTSD?

No, I am not making that claim.

But human emotions like fear and anxiety, they seem to have evolved from brain circuits

that you can find in animals.

And I've been talking to scientists to say that what you might call the building blocks

of emotions and of emotional disorders, they can be found not only in fruit flies, but

lots of other animals.

So one guy I talked to is Dr. Kerry Restler.

He's a psychiatrist at Harvard Medical School, McLean Hospital.

He told me PTSD involves an emotion that is meant to keep us alive, fear.

We really see PTSD as a disorder in which this evolved, important fear response is essentially

gone too far.

And so it's really almost unhinged, threat or fear emotion that is very hard to control

and that takes over people's lives.

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