The naked artist: Desmond Morris turns from body language to brush strokes

If his fledgling career as a surrealist artist had taken off, he might never have become a zoologist. But when he found he could not make a living from his paintings, Desmond Morris turned towards his other love - animals.

If his fledgling career as a surrealist artist had taken off, he might never have become a zoologist. But when he found he could not make a living from his paintings, Desmond Morris turned towards his other love - animals.

He went on to write The Naked Ape , which sold 18 million copies, and introduce the concept of body language in Manwatching , its successor.

Yet Morris never gave up the ambition of his early career when he once shared billing in a London gallery with the great surrealist Joan Miro. Indeed, he has exhibited his works every now and then since the 1970s, building a strong following among fans for whom Morris is one of the last surviving surrealists.

But a nagging suspicion that he still had one great work inside him eventually prompted him to devote the year 2004 to trying to produce it after four previous attempts failed.

Always a great admirer of the work of Hieronymus Bosch, he visited and studied all the artist's surviving masterpieces and took the precise dimensions of his Temptation of St Anthony as a template.

He then embarked on creating his own surrealist triptych in which the biomorphic beings that have populated his paintings since the 1940s would gather in a grand assembly.

The resulting magnus opus, entitled The Gathering and on sale for £70,000, was unveiled yesterday at the Mayor Gallery in Cork Street, London, to the evident delight of Morris, who turns 77 next month.

"Most of the time I'm never quite satisfied but this is the one painting I've ever done with which I'm completely satisfied. Manwatching and this triptych are the two things I will look back on and say I'm really pleased with," he said. "I can roll over and die now."

His art remains a little-known facet of one of Britain's best-known zoologists. "People often go into a gallery and say, 'This must be a different Desmond Morris. We can't believe it's the same one,'" he said.

Yet his art matters to him as much as his science. "I'm half analytical and objective while the other half is intuitive and subjective. This year, I've painted 40 pictures. Last year, I wrote three books. For me, it's a perfect balance."

Morris held his first exhibition, in Swindon, Wiltshire, where he grew up, even before he went off to study zoology at Birmingham University and then Oxford, the city where he lives today. He was already influenced by the surrealist movement which had begun in the year of his birth, 1928.

He knew that he wanted to use his knowledge of science "to invent my own world but obey biological rules," he said. "But if the surrealists hadn't existed, I probably wouldn't have had the nerve to do it. They showed me there was a way in which you could create another world."

In 1950, he had his first London show, at the London Galleries which was also exhibiting Miro, who became a friend. "I was the youngest of that group of painters, the surrealists, but my show in London was almost the last before the movement died out. After the Second World War, people just weren't interested so I appeared at just the wrong moment. When that gallery closed down, I was left high and dry. But I had this other obsession in my life, which was animals, so I became a professional zoologist and went on television and wrote lots of books on animals and humans. That's the career where I've become fairly well known, but my painting never stopped."

Yet, after 1952, he showed none of his art for 22 years, until he was persuaded to exhibit once more when he realised works he had once given to friends were beginning to turn up in the London auction houses.

The huge success of projects such as The Naked Ape , a frank study of human behaviour from a zoologist's perspective that was published in 1967, simply bought him years of time when he would retire from public life to the Mediterranean and paint.

Questioned as to whether Morris's art was as significant as his zoology, Andrew Murray, co-owner of the Mayor Gallery, pointed out that the London galleries were Britain's leading centre of surrealism in 1950. "When they had someone like Miro and then they also picked Desmond Morris, it shows he was obviously well looked-upon."

Nearly all the other surrealists are long dead, leaving Morris's zoomorphic creations looking almost strangely out of time and place, yet it is hard to begrudge Morris the satisfaction of achieving a lifetime ambition.