Thursday, June 23, 2011

The Blind Watchmaker by Richard Dawkins

My big takeaway from this book, subtitled “Why the evidence of evolution reveals a universe without design,” is that evolution is a scientific theory we will never fully understand. Dawkins says as much in his preface, as he describes multiple ways that the human brain seems to be designed to misunderstand “Darwinism,” and to find it hard to believe.

Another way is which we seem predisposed to disbelieve Darwinism is that our brains are built to deal with events on radically different timescales from those that characterize evolutionary change. We are equipped to appreciate processes that take seconds, minutes, years or, at most, decades to complete. Darwinism is a theory of cumulative processes so slow that they take between thousands and millions of decades to complete. All our intuitive judgments of what is probable turn out to be wrong by many orders of magnitude. Our well-tuned apparatus of skepticism and subjective probability-theory misfires by huge margins, because it is tuned—ironically, by evolution itself—to work within a lifetime of a few decades. It requires effort of the imagination to escape from the prison of familiar timescale, and effort that I shall try to assist.

I get this. Just as we can’t truly understand quantum events or accurately predict the motions of enormous galaxies. Like evolution, they operate on scales far removed from our daily world. And in evolution’s case, I firmly believe that we are additionally hampered by the limitations of our own language. We can’t even talk about evolution correctly. The right words don’t even exist and we are forced to deal with shallow approximations.

Don’t believe me? Dawkins’ first three chapters are dedicated almost exclusively to the idea that evolution, contrary to our popular understanding, is not driven by chance. The “cumulative selection” of evolution, he says, is very different from the “single-step selection” that so many mischaracterize as evolution. And he’s right, of course. But at the same time he’s wrong, because the things that are being selected, cumulatively or in single steps, are gene transcription errors and their resulting phenotypic expressions that have arisen by, guess what, chance. So it is both right and wrong to say evolution is driven by chance. It all depends on what kind of chance you’re talking about.

We need a new word to describe this kind of chance, because although gene mutations are random, which expressed traits survive in a population and which do not is clearly NOT random. They are driven by their environment, and certain environments will select and enhance certain traits, every time. As Dawkins does, quoting Peter Atkins provides a memorable way for getting this message across.

I shall take your mind on a journey. It is a journey of comprehension, taking us to the edge of space, time, and understanding. On it I shall argue that there is nothing that cannot be understood, that there is nothing that cannot be explained, and that everything is extraordinarily simple … A great deal of the universe does not need any explanation. Elephants, for instance. Once molecules have learnt to compete and to create other molecules in their own image, elephants, and things resembling elephants, will in due course be found roaming through the countryside.

Indeed. But I am helplessly compounding the problem, because I have already employed one of the language devices I was going to try and avoid in this blog post. Selection. When it comes to evolution, selection (natural or otherwise) is one of the most misleading and misconstrued words there is, referring, as it seems to, to some agency or agent that does the selecting. Nothing, it seems to me, could be further from the truth. Organisms better adapted to their environments live and reproduce. Organisms less well adapted do not. No organism consciously “passes on its genes” or is even driven to do so. And nothing “selects” which organisms will and which won’t.

Dawkins effectively tackles the first half of this concept—that reproduction is a natural and not a conscious process—when he talks about RNA molecules.

Experiments such as these help us to appreciate the entirely automatic and non-deliberate nature of natural selection. The replicase ‘machines’ don’t ‘know’ why they make RNA molecules: it is just a byproduct of their shape that they do. And the RNA molecules themselves don’t work out a strategy for getting themselves duplicated. Even if they could think, there is no obvious reason why any thinking entity should be motivated to make copies of itself. If I knew how to make copies of myself, I’m not sure that I would give the project high priority in competition with all the other things I want to do: why should I? But motivation is irrelevant for molecules. It is just that the structure of the viral RNA happens to be such that it makes cellular machinery churn out copies of itself. And if any entity, anywhere in the universe, happens to have the property of being good at making more copies of itself, then automatically more and more copies of that entity will obviously come into existence. Not only that but, since they automatically form lineages that are occasionally miscopied, later versions tend to be ‘better’ at making copies of themselves than earlier versions, because of the powerful processes of cumulative selection. It is all utterly simple and automatic. It is so predictable as to be almost inevitable.

Dawkins is making the case here, as he does throughout the book, that self-replication, evolution and life are all natural processes—not unlike crystallization and gravity. They don’t need deliberate action to operate. They are, in fact, intrinsic properties of matter itself.

And reproduction isn’t the only life process that is autonomic. In multiple places throughout his book, Dawkins variously ascribes our bodies, our thoughts, our behaviors—even structures we build in the world around us—as the physical manifestations of the genes we carry. Dawkins obviously thinks this of our bodies, and the bodies of all animals. They are the phenotypic expressions of the genes we carry. Specifically, genes working in combination with each other.

But because the environment of the gene consists, to such a salient degree, of other genes also being selected in the same gene pool, genes will be favoured if they are good at cooperating with other genes in the same gene pool. This is why large bodies of cells, working coherently towards the same cooperative ends, have evolved. This is why bodies exist, rather than separate replicators still battling it out in the primordial soup.

And there are other passages in which Dawkins clearly describes thoughts and behaviors as phenotypic expressions of genes. In his thorough treatment of sexual selection, he reinforces again and again the idea that in addition to certain physical traits of males, the preferences for those traits in the minds of the females are also being selected. Here, he’s talking about widow birds.

Instead of simply agreeing that females have whims, we regard female preference as a genetically influenced variable just like any other. Female preference is a quantitative variable, and we can assume that it is under the control of polygenes in just the same kind of way as male tail length itself. These polygenes may act on any of a wide variety of parts of the female’s brain, or even on her eyes; on anything that has the effect of altering the female’s preference.

He offers other examples for structures built by organisms (think beehives and beaver dams). They are all, he says, manifestations of genes, leading me to think that not just biology, but psychology, culture and even architecture may be driven by the mysterious force called natural selection.

But what is natural selection? And what is doing the selecting? The closest thing to truth that preserves the use of that word is, as I said before, the environment. The environment in which the organization lives does the selecting, but this is no conscious process either, and no comparative value judgments are being made over organisms that survive and reproduce and those that don’t. The environment isn’t doing anything, so how can it be said to be selecting? The environment is just the matrix in which the organisms struggle to survive, and some matrices are more amenable to certain variations than others.

These are extreme concepts, dancing around on the teetering edge of our language and ability to comprehend. But one extreme concept that not even Dawkins brings up is the thorny issue of free will. He doesn’t come right out and say it doesn’t exist, but I don’t see how one can conclude anything else based on what he does say. Let’s go back to the widow birds and the desire of their females for long tails.

The reason there is any momentum in the evolution towards longer tails is that, whenever a female chooses a male of the type she ‘likes’, she is, because of the non-random association of genes, choosing copies of the very genes that made her do the choosing.

The emphasis is mine. I don’t think this a sloppy word use on Dawkins’ part. The genes don’t just dictate the female widow bird’s thoughts, program her behaviors and instruct her how to build her nest. They actually force her to make choices about mate selection and, presumably, everything else. I don’t believe there is room for free will in Dawkins’ evolutionary universe. Not for widow birds and not for us.

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