"Sorry, Liz, I don't do small talk," my friend Michael tells me. "I'm only interested in big talk." It's the moment I want to bang my head on the restaurant table in despair. Why do so many clever, high-minded people think they're too good for gossip?

Gossip is fundamental to being human. This week Dr Nicholas Emler told the British Science Festival: "Language evolved to allow us to gossip and develop more complex societies than other animals. The one thing that sets us apart is that we can talk to each other. We can exchange social information."

I'd argue that gossip – which is a completely different thing from bitching – is an artform. You need to learn to sweat the small stuff. To be interested in the minutae of other people's lives. Otherwise friendship, a romantic date even, can feel like Maths A-level with more drinking. There's no let-up.

Mercilessly the big questions are lobbed over the net. "Who do you think should inherit Pinter's library?" "Did you read the new piece on Dorian Gray?" "Have you counted up how many awards Marco Pierre White has won over the years?" Bang, bang. Until you're pleading for mercy. No one can be that interesting, or that informed.

Don't get me wrong. I love these questions. But I do need a few non-sequiturs, a bit of silliness in-between. According to scientists, gossip makes us healthier. It boosts levels of progesterone, a hormone which reduces anxiety and stress. It fosters trust and co-operation. And, in times gone by, gossip proved vital to survival, with the trading of titbits helping cavemen catch thieves and elect leaders.

By gossip I don't mean the bare fact of Pete divorcing Jordan. It's the moment when you start debating – over red wine or afternoon tea or at the school gates – how hard it is if one person is more successful in a relationship. Or whether you expect sexual fidelity when one of you is damaged? The celebrity example is merely the litmus paper that lights the true conversation.

Women's friendships tend to be built on disclosure and support, while men's more often revolve around activities. But I always find it hilarious that men talking about football tactics for five hours is seen as grown-up, while women on shopping is childish.

In its broadest sense, friendship is an adult version of children's play. Play, as opposed to serious behaviour, appears to have no immediate benefits, but actually it promotes expressive skills – fun, joy, mimicry, telling jokes – so we feel in touch with our real self.

When I was younger I thought sexiness was beauty or bad temper or weird people in black polo necks who never talk to anyone else. Now I know – without a doubt – that it's charm, and the ability to keep a conversation going. It's a sign of an evolved person. It's the opposite of existential. It means you're in it together; you can pull it off.

Big Talk is intellectually thrilling. But it's the sound of one voice in the cave. The auteur, the solo player. What I love is the moment when your view on prison reform or ear-rings on small children, is completely changed by another person engaging with you, teasing out on idea, more importantly teasing you.

So, yes, by all means ask me the Pinter question. But I also need to know why your brother-in-law isn't talking to his wife. And so do you.