Fortunately, the new humans' enclosure at the zoo, next to five bemused langur monkeys and four nonplussed sloth bears, was populated by five of the more agreeable specimens of the genus Homo sapiens. Rather than destroying the planet, their main activities seemed to be playing "Connect Four" and listening to Radio 2. Three more human specimens will enter today.
Ms Cook, 28, a senior mammal keeper who normally looks after bears and apes, had just returned from delivering hula-hoops to ensure the "behavioural enrichment" of her new charges. She said: "They are far more demanding than my usual animals. We have to keep them occupied and entertained. I gave them a football to do some exercise. It is important to keep the weight off them."
The spectacle of five of the planet's most advanced great ape species hanging about in swimwear on Bear Mountain, the 91-year-old Grade II-listed terraces that once housed polar bears and grizzlies, is the opening salvo in a campaign by the Zoological Society of London (ZSL), which runs the zoo, to highlight humanity's status as a "plague species". Nearly 15,600 separate species are believed to be threatened with extinction caused by human activity.
To underline the point, displays outside the enclosure comparing humans with chimpanzees and gorillas note that more humans are born every hour than the existing population of the two other apes.
Managers were unapologetic about their selection of eight largely trim and shapely specimens, including an international kick-boxer and a professional dancer, to ensure maximum publicity by cavorting around the enclosure during open hours over the bank holiday weekend.
Simon Rayner, ZSL's communications manager, who dreamt up the idea, said: "The point is to jolt people into recognising the impact of human beings on their environment and that of other animals. We are saying, 'Look, here are humans stripped down and treated exactly the same way as other animals'. We are the same and the way we treat all animals has consequences."
The point was largely lost on 11-year-old Rory McDonald, from Purley, Surrey, as he gazed past the electric fence and moat at the cart-wheeling human exhibits. He said: "Cool, I want to have a go? It looks like Baywatch up there. And they even get a better view of the monkeys."
Justine Appleby, 34, a science teacher from Hertford, who was with her two young sons, said: "I did a double take when I saw them. For a split second, I found myself thinking, 'Blimey, what kind of animals are they?' It's actually quite a powerful message."
The exhibits will spend eight hours a day in their elevated nest and spend each night in their own beds. So far, life as zoological curiosities was proving highly acceptable, right down to the gourmet vegetarian lunch provided by the zoo's on-site catering firm.
Simon Spiro, 19, a veterinary science undergraduate at Pembroke College, Cambridge, shivered slightly as he sat in his boxer shorts and felt fig-leaves in a brisk wind. He said: "I leapt at the chance to do this. We've been sitting around, getting to know each other, discussing a bit about the philosophy of being behind bars. I'm fascinated by how we perceive animals and how they see us, so this is an opportunity to be on the receiving end."Reuse content