Wednesday, October 17, 2007

Natural Selection

This is a long and dense chapter - and if you are not inclined to be excited by long dissertations on the nitty-gritty of how species in the wild vary and change, I would recommend it as a strikingly effective sleep-aid. If this chapter isn't a form of Sominex applied to the printed page, I don't know what is. This isn't to say that the chapter contains nothing of interest - it does, and there are parts of it that are quite informative. But be prepared for a long slog, once Darwin gets some introductory material out of the way.

The capsule review: Variations arise within species (mutations, basically) - if a variation allows a population to become better adapted to the totality of the environment (note that this includes the other species present - and that changes in one species may make certain changes in another more advantageous) and thus survive to adulthood in greater numbers, that variation will spread - this is the process of Natural Selection. If a variation doesn't make a lifeform more robust, but increases its odd of successfully mating, or otherwise having more offspring than other forms, that variation will also spread - this is the process of Sexual Selection. Note that simply having an advantageous variation doesn't guarantee that a given specimen will survive, or out-compete its peers. A bird may have genes that make its feathers better insulators against the cold - this does it little good when a raccoon eats it in the egg. It gets a lot more complicated from there.

Now to back up to a very interesting point made early on. Semantics appears to be just as much an issue in Darwin's time as it is now, and we are told that people have many objections to the term "Natural Selection," one of them being that it implies that the altered species deliberately chose which new characteristics to adopt - and thus it cannot be applied to plants, since they have no volition. (Don't laugh too loudly - I've heard more idiotic things than that.) We are also told that some critics see Darwin's explanation of Natural Selection as describing Nature or evolution as an active force, with volition, and presumably a goal. Darwin says that personification of Nature in this way is unintentional, and to a certain degree, unavoidable. He mentions the way in which people commonly speak of gravity. Gravity is said to control the motions of objects in space, yet no one presumes that Gravity is an intelligent being, perched behind a drafting table with a protractor and a slide rule, calculating where it wants the Earth to be this time next month.

Darwin spends about a page comparing the human facility for shaping nature through various selective breeding techniques to the natural process of selection, and declares nature to be by far the better the better of the two. Given the understanding that Darwin much admired the skill and dedication that being a competent breeder requires, it's pretty clear that he stands in awe of the way that natural selection goes about its business - it's easy to see where people get the idea that he sees it as a deity from.

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