The human enclosure at the Edinburgh Zoo

Standing in front of enclosure 99 at Edinburgh Zoo, we looked in as the animals were stretching and bending together, moving rhythmically about the space. In one corner, a pair patted and poked each other as if testing what they could get away with. They seemed to be playing.

The animals we stared at through the perspex of the enclosure were apes, but not the kind you would usually expect to find at the zoo. These were the human variety.

The humans in question are part of a dance troupe led by choreographer Janis Claxton. As part of Scottish dance organisation Dance Base's program at the Edinburgh Fringe Festival, the troupe of men and women from Europe, Australia and China were performing a piece called Enclosure 99 Humans. The performance, which debuted at the Fringe festival in 2008 and runs seven hours a day for two weeks no matter the weather, was born of Claxton's fascination with the movements of animals. Her curiosity about ape movement in particular prompted her to study ape gestural communication with primatologist Klaus Zuberbühler of St Andrews University. In Enclosure 99, her troupe's movements and scenarios are inspired by apes they have observed at zoos around the world.

As we watched, the humans marched back and forth across their enclosure and then around the perimeter, as if patrolling their territory. Some of them started trying to make eye contact with others - who in turn tried to avoid that contact, making themselves appear submissive. Later the majority ganged up on one group member who fruitlessly searched for a corner where she could avoid their aggressive stares. Eventually one of the other humans took pity and helped her climb over a barrier and away from the others. I watched, mesmerised.

Claxton explained to me afterwards that their movements are intended to convey various attributes that humans share with other animals, such as dominance ranking, territoriality, empathy, cooperation and play. She hopes to increase awareness of the link between us and other animals; to demonstrate that we are connected with them through our behaviour.

We decided to have our picnic while watching the humans, and as I munched my sandwich I couldn't help noticing one of the group staring at me intently. It felt odd. I didn't know where to look, and every time I glanced up he was still looking at me. My kids started to get agitated. "They're looking at us, I don't like it", said my 12-year-old, as several of the other caged humans stood up and began to gawp at the spectating ones. It was an uncomfortable irony - who was looking at whom exactly?

The human enclosure at the Edinburgh ZooS

The dancers never spoke and they didn't react to anyone speaking to them. They only responded to movement and touch. Claxton explained that this was so that we had to focus on what their movement told us about their relationships - just as we would with other animals in the zoo that don't make vocalisations we can understand.

When it was feeding time, the gormless keeper, in a slapstick style comedy routine, brought the humans what looked like it might be Chinese takeaway in assorted containers. After eating, the humans decided to have a bit of fun with the keeper - hiding his broom and bucket, nicking his hat and throwing it among themselves while he haplessly tried to get it back. When the hat was chucked out to our side of the enclosure, my 9-year-old daughter ran to pick it up. Wise to the game now, instead of handing it back to the keeper when he came to collect it, she snatched it away at the last second and tossed it to another of the spectator humans. Suddenly there was a sense of shared purpose between the two groups of humans, with the feckless keeper as the conduit.

Claxton said the show is as much about what's going on outside of the enclosure as in it - she has been fascinated by the variety of reactions from zoo-goers who have been variously shocked, delighted, horrified and thrilled. Many people are intrigued by the concept, she said, and will sit for ages discussing ideas with their kids. But Claxton has also been castigated by creationists, and other visitors have walked away disgusted or refused to let their children watch.

"We've had that negative response," she said, "and then we've had really amazing responses where kids go, 'Nah mum, I think they're animals, I think humans are animals'."

Claxton is now seeking funding to bring Enclosure 99 to more zoos. For more information about the project, visit www.janisclaxton.com. This post originally appeared on New Scientist.