Tuesday, September 04, 2007

Evolution, prehistory, and Bill Bryson

Had the opportunity to read through Bill Bryson's A Short History Of Everything. A book that attempts to be pretty much what it says, focused on natural history as opposed to human events.

I have to say, there's a lot of good stuff in it. Having said that, it's obviously written for the lay reader. Although loaded with facts, it's written in far too avuncular a style. Anecdotes can certainly be worthwhile, but often enough the writing is just one big ramble. The narrative is not particularly chronological, well-ordered, or of uniform significance.

Yet there's a lot to learn from it. I got flavours that I wouldn't have found elsewhere (especially not in reference works) in subjects such as biology taxonomy, human evolution, and climate change through time.

One strand running through the narratives is that biology and prehistory are not the clearcut, proven sciences that are presented in textbooks and references. I can see some justification for those publications sticking to a relatively unitary consensus position of scientists, rather than muddying the narrative with the labyrinthine internecine disagreements within a given discipline. It is to Bryson's credit that he's not afraid of muddy waters.

A few gleanings.

Taxonomy. There are seven major levels in biology: kingdom, phylum, class, order, family, genus, species. Humans, for example, are respectively animalia, chordata (vertebrates), mammalia, primate, hominid, homo, homo sapiens. Most animals are in a small number of the phyla; most phyla are completely obscure for the lay reader. But how many phyla to divide things into is a matter of dispute: from the twenties to the eighties, with most people settling on a number in the thirties. And as Bryson indicates, the divisions are made more rational every so often, with much grumbling and revision of textbooks. Books from the 1970s, for example, are most definitely out of date.

Climate change. There has been a lot of change through the course of this planet. (None before was anthropogenic, of course.) Bryson reckons there are reasons to argue both ways on whether the global climate could get hotter or cooler: the creation of the Himalayas and the central american isthmus had major impacts simply through changes in air and water flows. Consensus goes for the warming, but tinkering with the climate globally (as some have suggested) can have thoroughly wild results.

Human evolution. Theory is based on so few solid fossil records that the whole discipline could arguably be construed as risible. Even New Scientist frequently reports new developments with a straight face, while acknowledging each time that there are major disagreements on interpretation. NS's latest argument was on whether Homo Habilis and Homo Erectus overlapped - not at all? or for a few million years? The available examples are just so rare.
My take is that human evolution has been gradual, and the reason for the different species characterisations is simply because so few fossils have been found that they can easily be separated into different species. Heaven help us when we dig up much more, and find the changes too gradual for such distinction.

And finally, Bryson demonstrates that there is still so much to be discovered, named and catalogued, in both fossil and living species. If you're keen enough, you can almost certainly find (or at least differentiate enough) a new species that you can name after yourself. Better do so before extinction: humans are estimated to cause thousands of extinctions each year, many of them species still unnamed.

We are certainly not at the end of the history of science.

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