Steve Reads

I’ve been especially lucky recently to have stumbled on a few books that are so good that they keep me enthralled for days. Gandhi’s autobiography did that, in part by its style and in part by my persistent arguing with him in my head. Dawkins’s Blind Watchmaker did the same thing, because I couldn’t escape the feeling throughout that I was learning something and that the next big ah-ha moment was in the next paragraph.

The book is a cleanly argued, generous, careful attack on most naïve denunciations of Darwinian selection. It falters a bit explaining the ways that other modes of selection may outpace Darwinian selection — for instance, the sexual selection that make peacocks with bright plumage reproductively successful. If we want to calculate the expected equilibrium size of peacock tail feathers, it seems as though we’d have to carefully document the reasons why increased plumage draws more ladies, and on the other side of the ledger the reasons why such plumage would seem to draw predators. Dawkins invokes the idea of a positive feedback loop, in which a slight preference in ancient female peacocks for brighter tail feathers led to a quick spiral in which all later female peacocks preferred them.

The reason for the initial arbitrary preference seems somewhat unclear. The canonical explanation seems to be that tail feathers are a cheap proxy for the health of the peacock: the brighter they are, the healthier is the bird. But this seems to bring in a lot of nasty game theory: peacocks with bad health who nonetheless managed to have nice tail feathers would fool peahens and breed more rapidly than their equally weak but less-bright brethren. It would then be in the females’ best interests (or rather, in the females’ genes’ best interests) to develop a facility for distinguishing between males that are merely faking good health, and those that are actually healthy; otherwise they would mate more often with unhealthy males and would pass on fewer copies of their genes than their fellow-peahens.

So that whole chapter turns out to be unconvincing. And the book as a whole could benefit from more citations and for-further-readings, though I did note some paper and book titles as I went along. I’m particularly intrigued by Dawkins’s praise for Kimura’s Neutral Theory of Molecular Evolution; Dawkins noted that Kimura’s skill at English writing is better than many native speakers’ talent in that area. Watson’s Molecular Biology of the Cell seems like it may be a good next step as well.

Most interesting to me were the connections between the structure of DNA and the theory of computation. How does DNA manage to be such an effective encoding device? How does it manage to pass along genetic information with such a low rate of error? What qualities would any chemical have to possess in order to successfully self-reproduce, as DNA does? This leads into a whole host of questions — and great writing on Dawkins’s part — about self-reproducing automata. He mentions von Neumann’s posthumously published book on the Theory of Self-Reproducing Automata, which is intriguing not least because of its author. The science-fictiony idea that DNA evolved from an earlier self-reproducing chemical, that it went on to create living organisms as a way to self-reproduce more effectively, that humans now pass information amongst themselves in the form of books as an extension of DNA, and that one day we may create robots which only dimly recall that their creators were human, is a mind-melter. It of course throws the Bible story into a queer light: perhaps god himself was just one earlier step in the DNA-to-human-to-books-to-robots story. Dawkins reminded me somewhat of Cloud Atlas in this way.

By the way, Dawkins dispenses with one strain of creationism with a literary flick of the wrist:

If we want to postulate a deity capable of engineering all the organized complexity in the world, either instantaneously or by guiding evolution, that deity must already have been vastly more complex in the first place. The creationist, whether a naive Bible-thumper or an educated bishop, simply postulates an already existing being of prodigious intelligence and complexity. If we are going to allow ourselves the luxury of postulating organized complexity without offering an explanation, we might as well make a job of it and simply postulate the existence of life as we know it! In short, divine creation, whether instantaneous or in the form of guided evolution, joins the list of other theories we have considered in this chapter. All give some superficial appearance of being alternatives to Darwinism, whose merits might be tested by an appeal to evidence. All turn out, on closer inspection, not to be rivals of Darwinism at all. The theory of evolution by cumulative natural selection is the only theory we know of that is in principle capable of explaining the existence of organized complexity. Even if the evidence did not favour it, it would still be the best theory available! In fact the evidence does favour it. But that is another story.

All around it’s an amazing book: well-argued, not above the head of anyone with clear-thinking skills, and intended to demolish a whole set of antiquated notions fairly. It goes into the small pantheon of great science books.