Sunday, 20 February 2011

The Greatest Show on Earth

The Greatest Show on Earth by Richard Dawkins

It felt like time for a bit of science, so I picked up this one. I'm a fan of Dawkins' books and have read several of his earlier works. This one's subtitle is The Evidence for Evolution. It seems crazy that here in the 21st century we still need to publish books on this subject, amazing that there are people out there who need convincing of it. Dawkins calls them (the creationists) 'history-deniers' and it is an apt name. What frightens me is that history-deniers, especially in the USA, teach in schools and colleges and run for high political office. Evolution is not a theory any longer - it's proven fact and there is an immense weight of evidence behind it. In my opinion (and Dawkins') only the spectacularly uninformed can argue against it.

Anyway, this book. Dawkins doesn't just argue his points, he demolishes any opposition step by step, systematically and comprehensively. He is a very good science writer, with the ability to lead the reader through some difficult concepts. He's entertaining as well. The book covers a wide range of topics from geology - the dating of rocks (which also dates the fossils in them and proves the earth is far older than the 10,000 years Creationists give it); embryology - how an organism grows from a single cell to a complex creature in just a few months; plate tectonics - explains why all marsupials are found in Australia and nowhere else; microbiology - experiments with generations of bacteria showing evolution happening before our very eyes.

It's all fascinating stuff. There were no ideas in this book which I didn't already know about but I loved reading about the evidence, research and experimentation which back them up. Some bits made me say wow, or laugh out loud. In mammals, there are two nerves running from the brain to the larynx. One goes straight there, the other goes down to the heart, loops around the aorta and back up again. In a giraffe, that's a bloody big detour. It's like that because of the way mammals have evolved from fish, and how each part of the body has evolved from some earlier organ. In sharks, the equivalent nerves don't have a detour. Oh you know what, I'm explaining this really badly - best to read the book yourself. But the point Dawkins is making with this chapter is that a so-called 'intelligent designer' would not have designed mammalian bodies like this. A designer would have gone back to the drawing board and routed the nerve sensibly. But evolution can't do that. It has to make do with tiny, step by step changes, and each change has to be an improvement on the last. So the nerve can't evolve a new route because the intermediate steps would be worse than before, not better. Once it finds itself looped around the aorta it just has to keep stretching as the giraffe's neck lengthens.

And why is the koala's pouch upside down with the opening at the bottom? Bit stupid for an animal who spends its time up trees. But when you discover the koala is evolved from a ground-living wombat-type creature who dug burrows with its front feet it makes perfect sense. You don't want to be shovelling dirt into your pouch, do you, much better to have the pouch opening backwards.

Anyway, I guess Dawkins is preaching to the converted here, if that isn't completely the wrong metaphor. In any case I have to agree with him when he says this.

No comments:

Post a Comment