How Mysterious is Evolution?
The basic mechanism of evolution is not mysterious at all. Random variation combined with natural selection is a fully intelligible means of biological change, perspicuously accounting for speciation. The abstract idea has a mathematical simplicity to it: (a) a process for generating outcomes at random, and (b) a method of selection imposed by some sort of agency (either agents with intentions or nature without intentions). So far this says nothing about implementation, which might introduce mysterious elements into the process: living tissue, DNA, sexual reproduction, competition, etc. In principle, the units could be anything, including blobs of ectoplasm or ideas in immaterial minds; and the method of selection could be a wise god’s decisions or holes through which objects can differentially pass. Random generation plus a filtering mechanism is all that is logically required. So the basic apparatus of Darwinian evolutionary theory is fully intelligible, not mysterious in the slightest. Compared to invoking God as creator, it is elementary arithmetic. Nothing could be clearer.
But that is not to say that evolution as we find it on planet earth is without mysterious elements. There are in fact puzzles aplenty, a few quite recalcitrant, some even deserving the name of mystery. Here is a list: the origins of life, sexual reproduction, altruism, dreaming, aging, bipedalism, syntax, suicide, fiction, modal thought, aesthetic sense, pure mathematics, music, dance, depression, mind and consciousness. None of these is easy to explain given what we know of the evolutionary process, chiefly because they seem surplus to survival requirements or even counter to survival. There is much that we don’t understand. We can wheel in spandrels and sexual selection to explain apparently non-adaptive traits, but that will only take us so far. A more streamlined biological world would consist of same-sex reproductive machines with no distractions tolerated. A Darwinian planet could easily consist of bacteria alone. But none of this should make us question the correctness of the basic theory, though we may wonder at its sufficiency. Nor should we surmise terminal mystery at this stage of intellectual history: the Darwinian theory is recent and there is still much to be learned. These are problems to solve not mysteries to resign ourselves to; puzzles not indications of intellectual limitation. Progress has been made on many of them; after all, it is only recently that the role of the gene has been properly understood, and DNA wasn’t discovered till late in the 20th century.
Well, that is true up until the last item on my list. Up to that point there is no compelling need to acknowledge deep mystery in the field of biology. The mechanism of evolution is not mysterious, and its products present at most puzzles (so far as we can see at present), but the existence of mind and consciousness is another matter. Here genuine mystery descends like a cloud on the evolutionary process: how could random genetic mutation and natural selection lead from an organism devoid of mind and consciousness to an organism with those things? The raw materials of evolution are chemicals that can combine, and the method is fundamentally rearrangement of those chemicals, so how could the process generate consciousness from such limited resources? At least under theism we inject consciousness into the process from the beginning (however illicitly). How could the selection of some bunches of chemicals over other bunches of chemicals lead to consciousness in those bunches? This is just a version of the mind-body problem seen temporally: the problem of emergence, as it is often called. Consciousness wasn’t there to begin with (unless we go panpsychist), so how did it emerge in the upshot? This seems like a miraculous qualitative leap quite at variance with the basic form of the theory. We can understand (more or less) how bunches of chemicals can get more complex over time, producing the things we call animal bodies, as mutations get selected and passed on, but how can this process produce consciousness from non-consciousness? To put it differently, only materialism seems able to account for the evolution of mind; but if materialism is false, then evolution is in trouble. The only alternative is to assume mystery and credit the process with properties that we don’t grasp, maybe can’t grasp. My point here is not to urge the merits of the mysterian philosophy; it is to observe that this is the only aspect of evolution that is genuinely mysterious. Of course, organisms are made of matter and matter itself poses some real mysteries; but the biological theory of evolution by mutation and natural selection is free of intractable mystery up to the moment when it has to explain the origin of consciousness. Darwin could write a book called The Origin of Species and hope to dispel the mysteries surrounding that topic, but he could not (and did not) write a book called The Origin of Consciousness and hope to provide an intelligible theory of that. Nor can anyone do it today. Yet consciousness is clearly an evolutionary product, as much as feet and brains. There seems to be something we are missing: what was the mutation that led to there being something it is like for the organism? How did subjective experience break into the objective world? And once it arose how did further iterations of it come about—novel forms of consciousness? Was there a specific mutation that led to the phenomenology color vision? How did gene selection produce sensations of red, say? Why conscious brains and not zombie brains?
Evolutionary theory as we have it thus combines an enviable lack of mystery with a very conspicuous mystery. At its core it is pure lucidity, but in practice it contains an enormous blind spot. It is both advanced and backward: everything a scientific theory should be yet afflicted with a gaping hole. The answer to my title question is therefore “not mysterious at all” and “utterly mysterious”, depending on where we look.