And this chimpanzee – he was called Congo – Congo's paintings were extraordinary because he did control them visually. He got no reward for them. If I tried to stop him in the middle of painting, he would scream and have a temper tantrum. If I tried to get him to go on after he'd finished a painting, he wouldn't. The lines were placed exactly where he wanted them on the page and he would have a basic quality of the artist which is thematic variation. He would develop a theme, like a fan pattern, and then he would vary it. He'd make this fan pattern and then he would split it in two and put a spot in the middle, or he'd make a little subsidiary fan to one side. And he was playing with abstract patterns and doing it for no reward at all other than the excitement of exploring visual patterns.

And I remember saying to somebody, 'They've called Lascaux the birth of art. Lascaux isn't the birth of art – it's the adolescence – this is the birth of art, this is the beginning of aesthetic expression. They may only be abstract patterns but they are visually controlled and varied'. And he did about 300 or 400 of these pictures. And eventually there was an exhibition of them at the ICA in London and people were surprised. Oh, of course the press had a field day with it, made jokes about it at the expense of modern art, which made me very cross, but the serious artists realised what was going on.

And Picasso had one of these Congo paintings, and when a journalist came in and rather sneeringly said, 'Oh, what do you think of this picture by this chimpanzee then?' Picasso bit him. Which I thought was a wonderful way of saying, the chimpanzee and I have something in common. And Picasso was very impressed. So was Salvador Dali. Dali said, 'The hand of the chimpanzee is quasi-human; the hand of Jackson Pollock is totally animal', which was a wonderful quote from Dali. And Miró – who I had that show with earlier on – Miró came to see me and said, 'I want one of Congo's paintings'. And so I gave him one – I had only a few left by this time – I gave him one and he was so pleased that he did a Miró in exchange for me. He sat down and did a Miró which is what a schoolboy would call a good swop.

So that was my Congo experiment and it led to a book called The Biology of Art which was my first serious book. And it fascinated me because it brought together my two passions: passion for animals and for art. I decided then that I would try to extend this research with chimpanzees and we did a number of other experiments with them. When I say experiments, I mean these were... I built a coconut shy, scaled down to take grapes so that the chimpanzee had to aim at these grapes as if they were coconuts in a coconut shy. And I was doing this because there was some debate about whether chimpanzees had good aiming ability because aiming ability was something which early human hunters had to have par excellence. It was very important in the history of our species that accurate aiming took place. And I wanted to see how... and a chimpanzee was able to knock a grape off with a... with a ball swinging on a chain. And we have it all on film and so you could... again, not only could you see the first germ of aesthetic behaviour in the chimpanzee, but you could also see the first signs of aiming behaviour.