Star rating **** Not too many in captivity, funding for companies being scarce. Some independent creatures survive in the wild, but for how long? Their keeper, Angus Balbernie, outlined his hopes for conservation: a breeding programme would preserve the most endangered sub-species.

Behind the dividing glass of Enclosure 44, the four humans - all female, in navy waterproof suits - were making the best of being outdoors in a downpour. They sat on rocky outcrops or under soggy trees. Snuggled a little, played games with stones. Noticed us watching them. Watched back. At which point, this durational dance piece - part of the Dance Base programme - begins to reveal the fascinating side to choreographer Janis Claxton's project. It's not just that she and the other dancers have devised "humanimal" behaviour or that, without speech, they convey defined personalities and relationship shifts within quarters devoid of privacy. What provokes the most disruptive thoughts is our reaction. We wave, giggle at their antics or exclaim at cleverness. We question Balbernie about their food, toilet-going and origins, and enjoy an illusion that is astutely rooted in reality.

Humans are animals (primate relatives are elsewhere on site). As we coo at the dancers - or the chimps - does the barrier between them and us make us forget to acknowledge and respect the link? Bold, brilliant. Go.

Until August 16 (not 11). Sponsored by Artemis.