I have spent the last few days working my way through Ken Miller’s new book Only a Theory: Evolution and the Battle for America’s Soul. (OAT) Short review: Worth reading, but also a bit disappointing. Now for the long review:
My first published piece of writing on evolution was a review of Miller’s book Finding Darwin’s God, (FDG) for Skeptic magazine. My reaction to the book was probably typical among atheists. The first half of the book is a masterful smackdown of creationism and intelligent design. Miller’s arguments were clear and convincing, and written in graceful prose that was a pleasure to read. In particular, his refutation of Behe’s arguments regarding irreducible complexity remains one of the best I have seen.
Then, somewhere around halfway through the book, you turn the page and are suddenly confronted with some very unconvincing (to put it kindly) religious arguments. Since I figured Skeptic’s readers were already aware of the vacuity of creationism and ID, I focused instead on the second half of the book.
Throughout FDG Miller made much of the contingency of the evolutionary process. He was keen to emphasize that the contingency of evolution is essential for God’s purposes. He strongly gave the impression that a world in which humans were foreordained would be harder to reconcile with Christian teaching than the world in which we actually find ourselves. See my review for exact quotes. This led me to make the following observation:
But surely God would have been disappointed if after ten billion years the sun went nova, its light never warming anything more sophisticated than colonies of bacteria! That’s the possibility that must be addressed before we can reconicle Christianity with contingency. Of course, it is conceivable that self-awareness could be foreordained where Homo sapiens are not. There is ample reason to believe this is untrue and Miller, at any rate, does not make this argument.
Well, now he does make that argument. Chapter Six of OAT is called, “The Universe That Knew We Were Coming,” and is devoted in large measure to supporting Simon Conway Morris’ argument from his book Life’s Solution. Conway Morris argued that a species possessing human-like intelligence was the inevitable end result of Darwinian evolution.
The theological importance of this point is clear. Stephen Jay Gould famously popularized the idea that if we were to rewind the tape of life and let evolution play out a second time, it is exceedingly unlikely that anything like human beings would ever evolve again. If he is right, then it becomes very difficult to argue that human beings are in any sense the purpose of creation. But if a species with sufficient intelligence to enter into a relationship with God was, indeed, inevitable, then we might be able to preserve that idea.
The trouble is that Miller’s (and Conway Morris’) argument for human inevitably is based almost entirely on the existence of evolutionary convergences. We frequently find animals from different evolutionary lineages converging on the same solutions to the adaptive problems they face. A simple example is the streamlined shape of dolphins and sharks. Darwinian evolution is constantly driving animals to seek out and explore the available niches in the environment, and this relentless pressure to adapt drives animals to constantly rediscover the same solutions over and over again. Miller sums up the argument like this:
Turning our attention to the special case of our own species, we can be fairly confident, just as Gould tells us, that our peculiar natural history would not repeat, and that self-awareness would not emerge from the primates. Indeed, we would have no reason to suppose that primates, mammals, or even vertebrates would emerge in a second running of the tape. But as life reexplored adaptive space, could we be certain that our niche would not be occupied? I would argue that we could be almost certain that it would be — that eventually evolution would produce an intelligent, self-aware, reflective creature endowed with a nervous system large enough to solve the very same questions that we have, and capable of discovering the very process that produced it, the process of evolution. To argue otherwise would be to maintain, against all evidence, that our appearance on this planet was not the product of repeatable natural events. It would be to maintain, for no particular reason, that this corner of adaptive space was found once by the evolutionary process but could never be found again. Everything we know about evolution suggests that it would, sooner or later, get to that niche. (pp. 152-153).
Actually, to argue otherwise is simply to acknowledge that Darwinian natural selection driving animals to fill adaptive niches is not the only thing that goes on during evolution. It was not just the relentless march of natural selection that made possible our appearance on this planet. There were also numerous mass extinctions to open up large numbers of new niches. The dinosaurs were the dominant large animals on the planet for more than a hundred million years, but the fossil record does not record any trend towards increased braininess during that time. Had the catastrophic event that brought on the extinction of the dinosaurs not occurred, what is the reason for thinking that self-aware animals would have evolved anyway?
There is also the problem of developmental constraints. It could well be impossible to design a big-brained reptile. Seen in that light, Miller’s admission that the primates might never have evolved a second time could be a damning one. He suggests that even vertebrates might not have evolved a second time. Does he also think that an intelligent, self-aware invertebrate was an evolutionary possibility? Seems a bit implausible. As Stephen Jay Gould pointed out:
Evidence for convergence requires multiple cases of independent evolution, while the example that we all carry closest to our hearts (and that engenders the emotional oomph in this debate)–the evolution of consciousness in Homo sapiens–remains an outstanding singleton in the only history of life we know: the story of our own planet. (I am not impressed by Conway Morris’s citation of octopuses, a group that I deeply admire and respect but that hasn’t, and presumably can’t, return the compliment via any higher mental functioning of its own. Consciousness at our level of language and conceptual abstraction has evolved but once on earth–in a small lineage of primates (some 200 species), within a small lineage of mammals (some 4,000 species, while the more successful beetles now number more than half a million), within a phylum that prevailed by contingent good fortune from the Burgess draw. If complex consciousness has evolved but once in the admittedly limited domain of known evidence, how can anyone defend the inevitability of its convergent evolution?
Frankly, the whole idea of niches existing in nature just waiting for animals to evolve their way into them is a bit dubious to begin with. Animals in part create their own niches, and the landscape is constantly changing as creatures evolve.
These are just a few of the scientific considerations that ought to dampen Miller’s confidence in the inevitably of human-like creatrues. Curiously, though, this whole line of argument resolves one theological difficulty only at the price of creating other ones.
Yes, human inevitability would solve the problem of preserving human specialness in the face of evolutionary contingency. But just consider the view of natural history entailed by this. Evolution by natural selection, you see, is an awful process. It is bloody, sadistic, and cruel. It flouts every moral precept we humans hold dear. It recognizes only survival and gene propagation, and even on those rare occasions where you find altruism and non-selfishness you can be certain that blind self-interest is lurking somewhere behind the scenes. All of this suffering, pain and misery, mind you, to reach a foreordained moment when self-awae creature finally appeared. What theological purpose was served by all this bloodsport? If humans were inevitable why didn’t God simply fast-forward the tape himself, thereby sparing all of those animals that died horrible deaths in the preceding hundreds of millions of years? Problem of evil, indeed.
If humans were not inevitable you could at least argue, as I understood Miller to be arguing in FDG, that this level of contingency was necessary if God were to make a genuinely free physical world, as opposed to one that languishes in the throes of a meaningless determinism. That line is no longer available to him. Reconciling evolution and Christianity is not as simple as theistic evolutionists often try to pretend.
Happily, this is only one chapter out of the book. When he’s addressing scientific topics, Miller is always excellent and this book is no exception. His descriptions of developments in genetics and evo-devo are marvelous. Most of his cultural commentary is also good, especially when he is explaining the importance of this subject to the future of American science.
The chapter addressing the major arguments of the ID folks is a bit mixed. Parts of it are good, but other parts are a bit lazy as well. Miller gives nice descriptions of how evolution can increase information (thereby refuting William Dembski’s silliness), and presents an interesting discussion of the evolution of the immune system in refuting Michael Behe.
But his discussion of the flagellum is a bit weak. Devoted followers of evolution/ID fights know that the flagellum is the poster child of ID, since it is a very complex system indeed. There’s actually quite a lot known about possible evolutionary trajectories for the flagellum, as described by Nick Matzke here.
Miller does not discuss any of it. Instead he simply points to the fact that of the thirty or so proteins that make up the flagellum there is a subset of around ten of them that form what is known as the type three secretory system (TTSS). This is significant because it shows that at least some of the proteins comprising the flagellum serve other purposes that could have been preserved by natural selection.
A good point, and one that definitely weakens Behe’s claims about irreducible complexity. But it hardly solves the problem. Evolving the flagellum still looks mighty challenging even after you have taken notice of the TTSS. The argument Miller presents here is essentially identical to the one he presented in his contribution to the Ruse/Dembski anthology Debating Design. There was far more he could have said then, and that is even more true today.
But rather than discuss this work Miller relies insted on the point that just because science lacks an explanation for some phenomenon today does not mean the problem will remain forever insoluble. This is a reasonable point, but it is rhetorically weak since it comes off as desperate. It allows the ID folks to talk about promissory notes and the like. It is the sort of thing you bring up at the end of a long discussion, after you’ve swamped your opponent in the moutnains of evidence that refutes his arguments. But Miller repeats it several times. This gives the impression that ID folks, whatever the deficiencies of their arguments, have at least put their fingers on some genuine problems for evolutionary biology. I fear that people reading this who are not steeped in the subject will come away thinking the ID folks have some points to make after all.
I have criticisms of other aspects of Miller’s book. There are a few places where I think he did not accurately present the arguments the ID folks are making, a fact I am sure they will delight in pointing out on their own blogs. And some of his sociological analysis strikes me as superficial. That is why I am a bit disappointed with the book overall.
But for all of that I definitely recommend reading it nevertheless. Even when I am disagreeing with Miller I am always engaged in his argument. I also feel like I learn something about how to write from reading his excellent prose.