Children perform in Grown Up at Camden People's Theatre
Children perform in Grown Up at Camden People's Theatre
© Adam Levy

WC Fields' mantra has long since been debunked. Some of the best theatre is made with animals and children – and for the very same reason that the straw-boatered Hollywood star warned his peers off them: they can't be controlled.

The same unpredictability that can ruin a shot on film runs a charge through theatre. The second an animal or a child saunters across a stage, anything might happen. Their presence reveals the liveness of an event, the reality of a performance. actors act, performers perform, and animals just are.

The generation gap is a chasm and they see the world in a way we never can

The idea has inched into the mainstream. Animals are everywhere. This year I've added a fox, a canary, crickets, stag beetles and insect larvae to my line-up of living creatures, and you'll find critters on the West End stage. Harry Potter might have sent its owls off to roost, but Curious Incident still comes with real rats and cute puppies. Each punctures a performance and reminds us what we're really watching.

Children sometimes do the same. Think of the babe-in-arms in Simon Stone's Yerma – too real to be boxed into the fiction – or the children playing behind one-way glass in Romeo Castellucci's Inferno. They were caged like animals or framed like art – exhibited as objects on show.

But children can be more than that. They can have agency onstage and since Company Three's Brainstorm transferred its teenagers to the National Theatre last year, kids are increasingly being treated as artists in their own right. It's a new thing. Even experimental artists like Tim Etchells and Gob Squad were making art of children not with them only a few years ago. That Night Follows Day was a text to be recited; Before Your Very Eyes a routine to be run-through.

From young mouths come sage answers – about love, loss and life – and the effect is funny and strange

Nowadays, artists tend to collaborate with children. Ontroerend Goed's teenage trilogy – a devised process that sought to enable self-expression – has been followed by the teenage singer-songwriters gigging in Kim Noble's Wild Life and the squeal of adolescent schoolgirls Lies Pauwels unleashed in The Hamilton Complex. At Camden People's Theatre last week, Gameshow and Emily Lim put five primary school children onstage to talk us through adulthood in Grown Up. They had supplied questions for elderly interviewees and, dressed in adult clothes, outsized blazers and cardigans, they read out the answers.

From young mouths come sage answers – about love, loss and life – and the effect is funny and strange. A lot of the theatrical interest comes from a similar disjuncture: young kids unaware that they're making sophisticated and self-aware theatre. They are at once in control and out of it. They own a room and keep a show on track, then get stuck in a jumper or lose their bearings behind a curtain.

In treating children as collaborators, participants and even artists, these shows help realise that future

Perhaps, in that, they reflect us back at ourselves – the children we feel like today and the selves we once were, all innocent and joyful and unspoiled. Every one of us can relate to them, but, being adults, none of us can entirely identify either. We are both connected and divided; the same but different.

That difference is huge. The generation gap is a chasm and they see the world in a way we never can – a child's eye view on the present. Touchscreens, to them, are a fact of life not a newfangled invention. So are we and the world we've helped shape. Watching children onstage, we see things through their eyes: the adults we are and the world we're passing on to them. They stand before us as the future – the thing we're striving towards, the point behind everything we do.

In giving them agency, treating children as collaborators, participants and even artists, these shows help realise that future. Behind the show, there's a process – one that pushes children to think for themselves, to venture off syllabus, beyond their usual experiences and their standard social groups. They come face to face with adults, those at the opposite end of life, and with artists who see the world in ways their parents and teachers might not. They go through something and emerge different people.

In that, putting children onstage is more than injecting reality into theatre. It's sewing theatre into reality – and that can only be a good thing.