[African Rift Valley soda lakes]. Steaming-hot water comes from volcanic springs and is so loaded with soda that around the margins of the lake it so… - David Attenborough

I don't know [why we're here]. People sometimes say to me, "Why don't you admit that the hummingbird, the butterfly, and the Bird-of-Paradise are proof of the wonderful things produced by Creation?" And I always say, "Well, when you say that, you've also got to think of a little boy sitting on a riverbank, like here, in West Africa, that's got a little worm, a living organism, that's in its eye and boring through its eyeballs and is slowly turning it blind. The creator God that you believe in, presumably, also made that little worm." Now I personally find that difficult to accommodate and so therefore [sic] when I make these films, I prefer to show what I know to be the facts, what I know to be true, and then people can deduce what they will from that.

This is the last programme in this natural history, and it's very different from all the others because it's been devoted to just one animal: ourselves. And that may have been a very misleading thing to have done. It may have given the impression that somehow man was the ultimate triumph of evolution, that all those thousands of millions of years of development had no purpose other than to put man on Earth. There is no scientific evidence whatsoever for such a belief. No reason to suppose that man's stay on Earth should be any longer than that of the dinosaurs. He may have learned how to control his environment, how to pass on information from one generation to another, but the very forces of evolution that brought him into existence here on these African plains are still at work elsewhere in the world, and if man were to disappear, for whatever reason, there is doubtless somewhere some small, unobtrusive creature that would seize the opportunity and, with a spurt of evolution, take man's place. But although denying a special place in the world may be becomingly modest, the fact remains that man has an unprecedented control over the world and everything in it. And so, whether he likes it or not, what happens next is very largely up to him.

Members of the auk family, such as these guillemots and puffins... propel themselves, not with their feet like ducks, but with their wings, and they have paid a considerable price to be able to do so... Auks have had to evolve shorter, stubbier wings. That gives them a rather clumsy, whirring flight in the air, but it does enable them to "fly" underwater so well that they can outpace small fish.