Professor Matthew Cobb

that changes human behaviour in any reliable way at all.

If, you know, we did a blindfold test, Chris, and you had shirts that your kids had worn as against some other kids, you might well be able to identify them because you know what your children smell like.

But that doesn't mean to say that it's all hardwired.

It means also there's this huge cultural and learned component.

Yeah, absolutely.

Well, I mean, I entirely agree with your feeling about the smell of baby.

That's my favourite smell in the world is the back of a baby's neck.

Oh, that's so nice.

Absolutely gorgeous.

So you could argue, you could construct a just-so story saying, well, yes, we've got to be nice to babies and that's why they've got these big round heads and we love things with big round hairs and all the rest of it.

And they've got this smell as well.

And clearly this is going to induce nice feelings of relaxation and make us less likely to be aggressive and whatever.

There's absolutely no evidence for this.

It might be true.

Proving it would be really, really hard because you'd have to get people who had no experience of bonding with a baby and therefore smelling it and saying, OK, well, what do you think about this?

And I mean, it would be really, really hard.

Very difficult experiment.

Well...

So part of the problem with smell is it's incredibly difficult to define and control.

There are hundreds of odours produced by our armpits.