Monday, November 17, 2008

The Ancestor's Tale

I'm just finishing up The Ancestor's Tale by Richard Dawkins, which is basically a description of the evolution of life on earth treated as a journey back through time to meet up with common ancestors.

It's been all right, filled with lots of interesting tidbits about various animals, but many times it just feels like Dawkins is riffing about whatever he wants to talk about at the moment. I blogged previously about his lengthy digression about race. In that section, he distinguished the concept of race from that of species by claiming that there was an objective scientific criteria for species. Namely, if individuals mate and reproduce under natural conditions, they're considered to be in the same species.

"Wait...what about asexual species?" I thought. Later in the book Dawkins brings up species that reproduce asexually, and admits that their designation to species is based on similarity judgments by scientists. In other words, the concept of species doesn't really have any firmer ground to stand on than any other classification in biology.

Another thing that bothered me was when he talked about why wheels haven't evolved, another topic I blogged about not too long ago. He pointed out that wheels aren't all that useful without roads. But then he goes on to point out what he says is probably the only example of wheels having evolved: the bacterial flagellum, which is a wheel-axle mechanism that freely rotates, whipping around a tail-like appendage that propels the bacteria forward. Well, if this is considered a true wheel, then we don't necessarily need to think about wheels purely as means of locomotion on land, do we? Why haven't they evolved in aquatic animals? In other words, why don't fish have rotors?

Anyway, it's been a pretty good read, but I'm glad it's nearly over.

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