This week I finished the audio version of The Blind Watchmaker by Richard Dawkins, which I discussed in my previous post, and I’d like to give a few responses to the book as a whole now that I’ve completed it.
Dawkins’ overall objective with this work is to describe how the dizzying mélange of organized complexity we find in the biological world can be explained by the properties of non-living matter, the blind mutations of genetic material in organisms, and the power of cumulative selection. He does an admirable job of this, but by the time I’d completed the book I realized I had questions about things that weren’t discussed by Dawkins. Also, the digressions he chose to make at the expense of adhering to the essential components of his explanatory thesis, ultimately disappointed me.
One of the most important assertions of the book is that there’s no point in the process of evolution we cannot explain from the previous. The trick to understanding the stunning complexity we behold in the world around us is to take something bedazzling, like the eye, and then imagine a series of very small steps that might have occurred over a very, very long time to produce it. If you put some sincere effort into it, says Dawkins, you’ll see there is some step-size small enough that you are able to imagine it. I agree this is doable.
What’s hard to envision is how there’s enough time for all of the teeny-tiny steps to have occurred, but Dawkins says that’s not supposed to be obvious. Our brains are not adapted to assess what a million years of time really is, never mind billions. An hour, sure. A lifetime, of course. We have some basic comprehension of a decade, a few generations of family, a century. Maybe a millennium. But a million years? It’s like staring into the sun.
The truth, he says, is that there’s been plenty of time. At known mutation rates, one biologist Dawkins referenced—whose name unfortunately escapes me—has calculated that a mouse could evolve to be the size of an elephant in just 60,000 years, if it weren’t for the obvious push-back such a mouse would receive from the forces of natural selection. In short, time is not the issue.
(There’s also chance enough for the really tricky parts, but that’s for another day.)
Natural selection is a cumulative selection process, meaning that it operates on inherited characteristics, and at each step of the way selects only the best-adapted individuals for reproduction. Because of its cumulative nature, it is more powerful than we may guess. It is sensitive, for instance, to the minuscule advantage delivered by each of the very small steps we envisioned above. In one example—the development of wings—he notes that a small flap of skin between the limbs or fingers of a rodent, no matter how small it might be, would help them navigate gaps between tree branches with just that much more reach and control. As a result, the organisms possessing this dermal oddity would have an advantage.
But how does such a sensitive process work when an organism is developing everything at once—eyes, ears, livers, brains, wings, bones, skin, hair, hearts, digestive tracts, vocal chords, etc.? Do we break all of those into tiny steps and overlay them? Clearly some of these must precede others, so it’s never really all at once. But it’s also clear that organisms evolve as wholes—simultaneously, if you will, with respect to one another, the environment, and the characteristics they already possess, which are already profoundly interwoven. Dawkins never addresses the question of how such a highly sensitive process selects for all of these mutually interacting adaptations concurrently. It might be a bad question on my part—so bad he didn’t think it needed to be addressed—but I’m curious.
In a chapter that comes much later, he provides an explanation for why the fossil record doesn’t show a steady development of particular features. Skull sizes in mammals for instance, would in theory follow some sort of progression. As brains enlarged in response to the increasing complexity of physical organisms and the adaptive advantage of intelligence, skull sizes had to increase to suit. More recent fossils should in general have larger skulls than earlier ones. That’s not always the case, but Dawkins has a reasonable explanation.
At any given time, variations in the expression of a given trait between members of the same species can be fairly significant. The largest human brains are about 40% larger by volume than the smallest ones, for instance. Given how spotty the fossil record is, we shouldn’t expect to discover a particular linear progression. This explanation makes sense in and of itself, but it left me uncertain about how to square the highly sensitive form of natural selection described above with the normal statistical variation for a trait within a species. Is there a contradiction here? I don’t know enough biology to know. It seems that either a tiny difference matters profoundly, or it doesn’t, right? I can imagine that the answer involves the phrase “it’s complicated,” and that both principles apply at different times, based on conditions and context. But Dawkins doesn’t address this. Again, I found myself wanting to understand how biologists may have reconciled these seemingly different conditions.
I’m running out of space here, but two more items were notable by omission. First, consciousness is not addressed at all. This is in keeping with the paradigm of hierarchical reductionism in which Dawkins operates, which he describes in one of the opening chapters. Presumably consciousness is no different qualitatively—in terms of explaining its origin—than mating behaviors or eyeballs. As such, there’s no real need to discuss it. For me, though, it’s an intriguing omission. I’m not sure that the equation of consciousness with rabbit ears rises to the level of common sense just yet.
It’s axiomatic, however, for Dawkins. He postulates (without saying this explicitly) a universe in which consciousness is the product of material evolution, and once he does this, the use of evolutionary theory to prove such a vantage becomes a circular argument. No more or less circular than a theist positing a God and finding evidence for this assertion, but circular nonetheless, so I can see why he leaves it alone. What he does feel obligated to emphasize is that he prefers his own form of circular argument to the ones made by “redneck creationists”—a preference the astute reader has comprehended long before he allows himself the satisfaction of name-calling.
Second, there is very little discussion of how the genome actually relates to the formation of the body itself. There is a really interesting passage on embryological development, but it is very high level. What Dawkins doesn’t address head-on is the need for particular types of relationships between genes and features. His examples throughout the book hinge upon the implication that infinitesimal differences in organisms not only afford them a reproductive advantage, but are inheritable, which means there must be clear genetic distinctions between an organism with a winglet that produces a few square millimeters of skin between two bones and one with a winglet a few square millimeters larger, and one with a winglet a few square millimeters larger than that, and so on.
One can easily imagine a genetic algorithm to produce this—there might be a gene that stores a value for how much skin to produce in a particular location, that could be adjusted like the volume dial on a radio—but that’s hardly the point. Dawkins himself argues that the genetic code is more like a recipe than a blueprint for each and every bit of tissue, so how does this work? Without a hereditary mechanism that is as granular as the countless tiny steps taken by evolution itself, the explanation given by Dawkins would break down. Aside from being a necessary element to deliver a cogent thesis, the question is also a fascinating one, but it is left untouched. We are left to assume that it’s perfectly obvious the genetic algorithms within an organism’s DNA contain the specificity and granularity required to accommodate, uniquely, each digitized step in evolutionary unfolding.
Given the state of genetics at the time the book was written, maybe Dawkins wished he could have said more on the subject, too. I would have much rather he mused on this topic than on the theory of how life might have begun as self-replicating crystals in seasonal streams, or the differences between various forms of taxonomy, or on disputes between various fields of evolutionary research. He included these topics principally to disarm the theists, I believe, not because they’re vital to an explanation of adaptive complexity.
This leads to the central failing of the book as a whole for me: it left intriguing scientific questions central to his argument untouched, and focused on philosophical pursuits instead. The result is a book that suffers for being of two minds. We lose the incandescent thread of wonder at life’s uncanny success, and find ourselves instead as audience to a squabble. For me there’s no squabble per se, so this was a distraction. But the questions raised were enjoyable to ponder, and I look forward to finding other works and authors in the future who may have addressed such questions.