Last Chance To See

by Douglas Adams

The tourists with their cans of lager and their ‘Fuck off’ T-shirts were particularly familiar to anyone who has seen the English at play in Spain or Greece, but I suddenly realised as I watched this that for once I didn’t need to hide myself away in embarrassment. They weren’t English. They were Australian. But they were otherwise so nearly identical that it started me thinking about convergent evolution, which I had better explain before I go on to say why they made me think of it. In different parts of the world strikingly similar but completely unrelated forms of life will emerge in response to similar conditions and habitats. For instance, the aye-aye, the lemur Mark and I originally tracked down in Madagascar, has one particularly remarkable feature. Its third finger is much longer than its other fingers and is skeletally thin, almost like a twig. It uses this finger for poking around under the bark of the trees it lives in to dig out the grubs which it feeds on. There is one other creature in the world which does this, and that is the long-fingered possum, which is found in New Guinea. It has a long and skeletally thin fourth finger, which it uses for precisely the same purpose. There is no family relationship between these two animals at all, and the only common factor between them is this: an absence of woodpeckers. There are no woodpeckers in Madagascar, and no woodpeckers in Papua New Guinea. This means that there is a food source – the grubs under the bark – go...

Convergent evolution