It's the simplest idea. As [Thomas Henry] Huxley said, 'If only I'd thought of that'. It's quite extraordinarily simple, easy, elegant. And you need a few preconditions to think this up, which Wallace and Darwin both had. You have to... you don't have to have read Malthus, but you have to know that every bird and mammal and insect produces far more children than could possibly survive. We're the only exception now, we weren't then. So what's happening? That's the first thing. An awful lot die. You know, you have two robins in your garden, they may produce 14 young, you still have two robins in your garden the next year. They may not be the same ones. What's being eliminated? Answer: tremendous pressure.

And this is why it is so offensive and why people don't remember, or want to remember. It's the central role of death. The robin story means at least ten robins are going to die. Who's going to survive? The guys with an advantage. It's simple. You can actually see it happening on the Galapagos. And they will produce more babies and that will be a different population. It's easy, evolution by natural selection. And then you have to add the thing that actually Darwin had absolutely got right, but nobody realised. Ernst Mayr, a great man who I did know, who did come stay here a lot. He realised you've got to add geography in. You can't just imagine things in a timescale without putting them into the real world. They've got to be there in... in the landscape.

Now, if a mountain range comes up, bang, they can't interbreed. You've got to have isolation. Isolation on an island, new species, isolation in so-called refugia. So a lot of the jungle dries out, a different monkey would evolve there, from the same stock, but this one, for some reason, whatever the mutation has been, this one will... will the females will find that sexy if he goes... and has a white spot on his nose. But if he's got white either side and he goes... and she's not interested if he does that. She just goes for the ones like you with the white nose and the flash.

And it's all... it's all so wonderfully... well, it's entertaining and satisfying, and then you add time. You go back 4.2 billion years, and then you're really talking. I can show you a hagfish, the earliest hag... well, the earliest fish in the sea, as far as we know. Too primitive... I'll get it.