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Does Evolution Have a Direction?

An image comparing human and other primate skeletons, taken from German biologist Ernst Haeckel's 1897 book The Evolution of Man.

For many years, I taught Plato’s Republic to first-year undergraduates. It was great fun, but one part of the book always puzzled them. We spent most of the semester with Plato building up his ideal society — different kinds of people with various skills were educated accordingly and matched to the professions best suited to them. And then, at the end, it all came tumbling down. Rather than picking the best person for each job, the rulers would appoint their own kids and so forth; the perfect regime would be perfect no more. I used to explain to my students that for Plato there was nothing anomalous about this. Though he thought that mathematics was eternal — 2+2=4 never suddenly became true and it will never become false — this physical world of ours is always changing. Nothing is permanent in our actual lives and history, which has no particular aim, no direction.

This view changed when Jewish thought came on the scene and entered into mainstream culture. Jewish philosophers and theologians — like the Christians who came after them — thought in historical terms. More than this, they thought history had a direction. God created the world sequentially and intervened in historical events to direct his chosen people. And then, according to Christians, God decided that He must intervene decisively to rectify the fall of mankind. And so we get the story of Jesus: his sacrifice on the cross, subsequent resurrection, the possibility of our eternal salvation, and the prophecy of his eventual return, heralding a New Heaven and a New Earth. There is a story with a direction — and it is one in which humans, though not the only interests of God in His creation, play a pretty central role. Warthogs are not made in the image of God, nor is there a warthogian eschatology pointing to their future bliss.

Next came the Enlightenment in the eighteenth century and, for various reasons, science being prominent among them, people started to look for an alternative, more secular view of history. A candidate was soon on offer: the idea of progress. As opposed to the Christian notion of Providence — where our only hope for salvation was through God’s benevolent action in history — now with progress the hope was instilled that we through our own unaided effort can make things better, scientifically, medically, politically, culturally.

Almost immediately, people started to cash this out in the biological world. There had long been the idea of a chain of being, where all organisms can be put on a scale, a ladder or staircase if you like, from the most primitive grubs, up through the “lesser” animals, until we reach the summit, humankind. If you were so inclined, you could extend the ladder skywards to include angels and then God at the top. The chain of being was originally static, but soon it was made to move — a kind of escalator — and so the idea of evolution (it wasn’t called that until the mid-nineteenth century) was born. As we have progress in the social world, from the “savages” (as they were called) to Europeans — some debate about which Europeans, but the English knew the answer to that one, especially given that God is not just English-speaking but also an Anglican — so also we have progress in the organic world, as they used to say, from the “monad to the man.”

Erasmus Darwin, the eighteenth-century British physician and grandfather of Charles, wrote a lot of bad poetry on the subject:

Imperious man, who rules the bestial crowd,
Of language, reason, and reflection proud,
With brow erect who scorns this earthy sod,
And styles himself the image of his God;
Arose from rudiments of form and sense,
An embryon point, or microscopic ens!

Fast forward to the middle of the nineteenth century when, in 1859, Charles Darwin published On the Origin of Species by Means of Natural Selection, or, the Preservation of Favoured Races in the Struggle for Life. It is generally agreed that Darwin did two things. First, he made common sense the idea of organic evolution, that all organisms including humans came into being by a slow, natural process of development, from much more primitive forms, which probably — Darwin implied this but was not explicit — emerged from non-living minerals. Second, he offered a mechanism for this change. More organisms are born than can survive and reproduce. There is a struggle for existence in which some win and some lose. Winning and losing is on average a function of the differences between organisms — some features help and some don’t — and so there is a natural equivalent to the breeder’s practice of selection, and this adds up to overall lasting change.

At what price was there progress up to humans? Darwin certainly believed in social progress, and it is pretty clear also that he believed in evolutionary progress. But he saw a problem with this idea, a problem that is still with us today. Natural selection doesn’t select for what’s best in any absolute sense, but just what’s best at surviving relative to the conditions that organisms find themselves in — whatever wins in the struggle for existence, wins. If there is lots of food, bigger animals win; if food is scarce, smaller ones win. Given that brains are high-maintenance features, there is absolutely no binding necessity that they evolve, even less that they get bigger and bigger through evolutionary history. At the same time, the raw building blocks of evolution — what we today call “mutations” — are random, not in the sense of being uncaused, but in the sense of not appearing to order. While you might need a new skin color for camouflage to survive, there is no guarantee that you will get it. So the problem is this: If natural selection doesn’t select what’s best in an absolute sense and mutations are never guaranteed, can there be any direction to evolution?

We have had a hundred and fifty years of agonizing over this one. You can solve the problem by simply denying that evolution has any direction. Interestingly, although they may be uncomfortable admitting it in public, many, if not most, professional evolutionists seem to think there has to be a direction that leads to us humans. And this holds true of agnostics and atheists as much as Christians and other religious people. For instance, Edward O. Wilson, the Harvard sociobiologist, is quite open in his belief in an evolutionary direction, as is the prominent “new atheist” Richard Dawkins. As Dawkins put it: “Directionalist common sense surely wins on the very long time scale: once there was only blue-green slime and now there are sharp-eyed metazoa.”

Another way to solve the problem is by getting God back to work. Perhaps every now and then He gives the mutations a friendly shove in the right direction, and, lo and behold, here we are. This was the position of Darwin’s good friend, the American botanist Asa Gray, and today a version of this is endorsed by the theologian and scientist Robert John Russell. Most scientists, including believers, don’t much care for this idea. They may not all be metaphysical naturalists, denying God because nothing supernatural can exist, but they are methodological naturalists, keeping God out of science, no matter what they do on Sundays.

How then to stay secular and still get the idea of progress or direction into evolution? There are two popular approaches to this problem today — both of which go back to Darwin himself. The first, which is enthusiastically endorsed by Dawkins, rests on the notion of biological “arms races.” Lines of organisms will often compete, and there is comparative progress — the predator gets faster, the prey gets faster. Dawkins points out that in military arms races there has been ever-increasing reliance on electronic gadgets, and so it is no surprise that an organism has evolved with the biggest on-board computer of them all, the brain. Though these biological arms races begin as relative progress, they can add up to absolute progress.

A second approach, championed by Cambridge paleontologist Simon Conway Morris, argues that there are ecological niches that organisms seek out and occupy. There was one, for instance, waiting for a cat-like animal with large, shearing-type teeth. Wonder of wonders, at least two different lines discovered this niche — placental saber-toothed tigers and marsupial saber-toothed tigers — and both evolved to occupy it for a while. Obviously, there must have also been a niche for a cultural, language- and tool-using organism out there, and it was found out too, by us humans. So really, while it might not have been exactly us at the time when we did enter in — no one, for instance, is saying that we had to be hairless and so forth — some intelligent organism would have turned up sooner or later to fill the niche. And, from what we know about evolution, that probably would have happened sooner rather than later.

Not surprisingly, there is much controversy about these suggestions. Some have wanted to turn away from the whole Darwinian enterprise. Could it not be that, even without selection, evolutionary change is bound to happen, that complexity is bound to emerge from simplicity, so that, in the end, humans are to be expected? Might the unaided laws of physics do it all for us? According to the computational theories of Stuart Kauffman, these laws can, to use his felicitous phrase, give us “order for free.” Although it is hard to pin down the exact position of a thinker who embodied more change in one ontogeny than most phylogenies do in eons, it is probably this kind of thinking towards which the late Stephen Jay Gould was moving in his final years.

So we don’t seem to have gotten much closer to the idea of direction. Leaving aside the theological suggestions as inappropriate to natural science — too often what one generation finds miraculous is explained naturally by the next — there is surely merit in all of the secular suggestions, even the non-Darwinian varieties. However, equally surely, none of these suggestions, as they stand, guarantees any kind of absolute progress — the inevitable evolution of human beings or human-like beings. Some arms races end in disaster as organisms go down ever-more specialized directions with no hope of escape. It is hard to imagine how peacocks will produce an avian Socrates. Perhaps bigger brains are likely, if not on our planet then somewhere in the universe. The same goes for the existing-niche idea, although some ecologists wonder if the notion of niches that exist objectively, prior to the organisms that inhabit them, makes any sense. Even if it does, what guarantees that we, or any other organism, were able to discover the ecological niche that was out there waiting for human culture? As for order for free, I doubt even the most ardent computer enthusiasts are totally confident that blind laws whirling endlessly will do the job. One thinks of monkeys typing Shakespeare — or not.

There are those who agree that theological suggestions for finding direction to evolution aren’t right for science but who do wish to reconcile science and religion (so-called “accommodationists”). They have a problem on their hands. At least, folks who would reconcile science and the Abrahamic religions — and probably some of the Eastern religions, too — have a problem on their hands. For them, humans, or human-like beings, are not just something that might or might not have arrived on the scene. They are central to God’s creation. They are His children, for whom He cares and over whom He weeps. They are the beings for whom, in the Christian religion at least, He was prepared to make the ultimate sacrifice on the cross. Not just the agony from the nails but the agony of indifference. “My God, my God, why hast thou forsaken me?” But a theory that shows how evolution made human life possible isn’t good enough to comport with this idea. For Christians who want to accommodate modern science, evolution must do it. They — and non-believers like myself who are sympathetic to Christianity — have the problem that they need more certainty about evolutionary progress than biologists seem able to provide.

What is to be done? Here is a suggestion, more to get the discussion going than to close debate. What about multiverses? Suppose there are an infinite number of universes more or less like ours. We know that humans can evolve because they have evolved. Isn’t it the case, therefore, that, given an infinite number of universes, somewhere, sometime, we are going to get humans? I am not sure that in this case, where there must be billions and billions of failures, I want to use the word “progress.” But it would be the case that we would have to turn up somehow, somewhere, sometime. And here, perhaps, we can put Augustinian theology to good use. God is outside time and space. Unlike us, He is not cooling His heels, waiting for the show to get off the ground. For Him, it is always now; we are always evolved, at least in one possible universe.

I think I have by now made quite enough claims that will be totally unacceptable to both right-thinking Darwinians and to right-thinking Christians. Let’s leave it at that. You do better!

Discussion Questions:

  1. To what extent does the Enlightenment idea of progress influence our understanding of evolution?
  2. Is the idea of evolution without direction incompatible with theism?
  3. How else might we understand the idea that evolution has a direction from a secular point of view?
  4. How much freedom or flexibility does the Christian have in considering what kind of being we might have been while still being “made in the image of God”? Could we have been asexual? Could we have had three sexes? Could we have been cannibals? Could we have been old-aged at twenty?