Sir David Attenborough shows his knuckles, a sure sign of aggression in primates – not least the naked ape. "Are you a vegetarian?" he asks. The question is strange on several fronts, but particularly in its confrontational tone.
I am used to his near-breathless whispers, his heightened adjectives, the feeling that, if he were to talk any louder, some animal, somewhere in the world, would get startled and savage itself. His voice, his presence, has been in the nation's living rooms for half a century.
Today, Attenborough is at the Queen's Gallery, Holyrood, surveying the newly opened Amazing Rare Things exhibition, which he co-curated. Dubbed "the art of natural history in the Age of Discovery", it covers the explosion of interest in what was very much the New World, featuring studies by Leonardo da Vinci and others from the Royal Collection.
"Would you think it's wrong to eat an animal?" asks Attenborough. He smiles, a show of bared teeth. He has me pinned like a butterfly and I manage a timid "no". "Well I don't think it's wrong to collect a specimen, and certainly not in the 16th or 17th century."
These questions were prompted by a picture of a caiman – a creature which was pickled in brandy by the 17th- century naturalist Maria Sibylla Merian. "Human beings weren't threatening the world back then," says Attenborough.
"When you went to the New World, with its vast areas of forest and very few people, what you were trying to do was make sense of that overwhelming reality. You are seeing things that are utterly different from anything in your experience, animals that live upside down, hanging from the tops of trees. Bizarre."
One such animal at the exhibition is the three-toed sloth, painted the wrong way up, from the collection of Cassiano dal Pozzo. To me it looks funny, like a bear. Attenborough views it as an "honest mistake", made with the "best will in the world".
Other anomalies include da Vinci's anatomic drawings of "real" dragons, the mismatching of insects and their prey, a bison leaping deftly through the twig of a tree. But for all their naivety, Attenborough admits envying the thrill of first contact.
"I don't think it's particularly distinguished in an intellectual way to feel like that but it's true," he says. "If you see something and think, Golly, I'm the first human being to see that,' or at any rate the first European to see that, it's pretty exciting. Just imagine if someone came back with these fantastic animals, birds and plants, with such surprises "
My imagining is cut short. Just for a second, he studies me with the same intense interest I've seen him focus on hyenas, floodplains, dung. "Would you be interested or would you not?"
I nod and suggest what seems obvious: that Attenborough has broken his own share of new territories. As the man at the helm of one groundbreaking television series after another, he has done for natural history what Charles Manson did for serial killing. Along with the Michael Jacksons, the Stevie Wonders, the David Hasselhoffs, his is one of the world's few truly universal faces.
Being the first person to film limas in Madagascar, he says, was a particular career highlight, and might compare in some small way. But despite his complaint that there are no new frontiers for the pioneering naturalist, or any that "haven't been photographed by Google", he must be aware of his contribution.
"Oh, it's minimal," he says. "I've spent my time conveying images of the natural world to electronic devices like a camera." It seems a modest, if slightly bullish, reply. Is he not part, at least, of the continuum of naturalists who have brought the world to a wider audience? "I guess."
His next project, Life In Cold Blood, studies amphibians and reptiles, and is reported to be his last. But despite his age – he will be 82 by the time the programme airs in 2008 – he shrugs off any suggestion of retirement.
Looking back over his career, it's not easy to pick out favourite places but he puts Borneo and Papua New Guinea near the top. In addition to narrating, he still travels widely but admits certain things are now unlikely.
"I haven't been to central Asia and would very much like to have done that," he says. "The time has passed. I'm not looking forward to walking 12 hours a day with a handful of sun-cracked maize. Curdled yak's milk is not for me any more, but it would have been 20 years ago."
Raising awareness for endangered species, he says, has been a useful by-product of his work, an issue brought to the fore by several of the paintings in the exhibition. A portrait of the passenger pigeon – so abundant in the 19th century that its huge flocks "blocked the sun" – has survived, whereas the birds themselves are extinct.
Shining a light on the modern-day equivalents, says Attenborough, has had "considerable" effect.
"Nobody's going to get wildly excited about preserving something when they don't know what it is," he says. "Over half the human population is urbanised these days, cut off from the natural world. If we're not very careful we get into a situation where people ask why they should care about the natural world. It never occurs to them that we are reliant on the natural world for the very air we breathe and all the food we eat. Humanity can't exist without it so it's very important to keep in touch."
The appetite for programmes of Attenborough's kind is definitely not nearing extinction, thanks in part, he says, to the circle of life. "People are constantly being born," he points out. "There are children now who haven't seen films of a lion killing the wildebeest. It seems inconceivable when you think of the number of times we've shown it."
What's even more extraordinary, he thinks, is that people who have seen such stories 50 times already are happy to see them again, rejigged, re-examined or just repeated. Why this should be the case is beyond him but it might help with conserving certain species. Whether he feels personally optimistic, he adds, is "neither here nor there".
"All I know is that it's extremely important that it should be done," he says. "Whether we're going to lose 5% or 50% of the animals in this world within the next century is almost irrelevant. We have to do everything possible to conserve them."
In the course of our discussion certain behavioural patterns emerge: questions of a scientific kind get full-bodied answers; those of a personal nature invariably get short shrift. In the middle-ground are the more theoretical questions, such as: who would take over the world if humans were extinct?
"Take your pick," he says, "but they would have to be omnivorous and able to live in a great range of environments." His own money is on rats or cockroaches. As to the profile of people that might not enjoy the Amazing Rare Things exhibition, he seems for the first time at a genuine loss.
"There could be somebody who's not in the least bit interested by a flower or an insect or a bird or a mammal, not interested in any animal living or dead, and I'd suggest that he shouldn't waste any time and should perhaps just go to sleep."
Before slipping out and leaving the king ape alone, I ask Attenborough how we should best remember him. "I'm not concerned," he whispers. "I don't mind."
First published in The Sunday Herald, 2007.