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Chris, knock, knock.

Who's there?

Doctor.

Doctor who?

I know we're on the BBC, but it's actually Dr. Zand.

For today's daily dose, we are returning to the subject of laughter.

That did actually get a smile out of you.

Oh, it's quite funny.

We're revisiting the subject with Professor Sophie Scott, CBE.

She is an incredible expert in the neuroscience of laughter.

She's based at University College London.

And she explained to us how laughter in humans is, in fact,

a positive evolutionary trait.

So this is one of the really interesting things about humans and other animals.

So you do find laughter in other animals, particularly other primates.

But there are some distinct differences between human laughter and laughter in other animals.

And one of them is that non-physical things will make human babies laugh right from the outset.

So peek-a-boo, tearing a piece of paper, jiggling your keys, looking like you intend to make them laugh.

So there's something about laughter being able to work at a distance.

I do a thing where I start singing, I go, old McDonald,

and I start good.

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