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 and attributed to English biologist Thomas Henry Huxley.An image comparing human and other primate skeletons, taken from German biologist Ernst Haeckel's 1897 book The Evolution of Man and attributed to English biologist Thomas Henry Huxley.Wikimedia Commons

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?

9 Responses

  1. I think that there is a very significant omission in this essay, and that is the consideration that Ruse’s use of the term “evolution”” implies macroevolution, for which there seems to be less and less evidence, not more. The entire theory is on shaky grounds, and I doubt it will withstand much more scientific scrutiny before it is discarded. We all know that incremental changes based on genetic mutation occurs within species (microevolution); no one doubts that. But I am very curious why Ruse never mentions any of the mounting objections to macroevolution, which he needs be true for his worldview to be accurate.

    That said, I always found it curious that “progress,” or increasing complexity with time, is the exact opposite of what we should expect, given the second law of thermodynamics. We are so accustomed to the idea, living in such beautifully ordered universe. But that order is just taken for granted. It’s the exact opposite of what we would expect.

    Thirdly, it just seems that positing a multiverse is a grasping at straws. There is absolutely no scientific evidence for it. It seems patently obvious that many academics will go to any length, dream up any fantastical theory, in order to escape a providential, loving god.

    • Michael Ruse Michael Ruse says:

      Well, obviously, there is not much chance of a meeting of minds here. I regard evolution — macro, micro, mini, maxi — as one of the indubitable truths of all time — a true testament that we are made in the image of God (if such there be), that grubby little primates such as we can ferret out the great truths of our origins. There are of course discussions about mechanisms, but no serious scientist doubts evolution. How else do you explain the fossil record, the distributions of organisms around the globe, the similarities of embryos, or anatomy, and now most remarkably the similarities down at the molecular level — the joy is in discovering this glorious universe, not denying it.

      No one denies that heat death is the ultimate fate of all — but evolution reverses the trend for a while — no paradox in this

      I introduced multiverses to affirm the existence of God, not to deny Him — the point is that if Darwinism is true, you need a solution to the necessity of human existence, and I offered one.

  2. R. Wolf says:

    I like this article, because it is written without complicating professional jargon. A number of the tentative ideas discussed here with such ease and clarity seem almost (?) desperate to allow for human origins emanating, as it were, from some field or “realm of Ultimate Concern.” Personally, I resist the image of God suddenly jumping into the mix at the center of the pie. On the other hand, I resist any true *scientist* claiming that “nothing supernatural can exist.” That claim in itself seems to suggest that the *scientist* must himself be God, that is, must know everything there is to know in order to make such an absolute claim, by which claim he would appear in some fundamental way also to cancel-out his own existence (if one accepts the nature and substance of “God” as usually defined). And when we say “supernatural,” do we mean “above nature” as in “above human nature,” or above and beyond the grasp of empirical knowledge, or somehow entirely outside the “natural order” of the world (Reality) entirely? Is Gödel’s theorem somewhere at work here in, say, the deep unsolicited background?

    • Michael Ruse Michael Ruse says:

      I was certainly not saying that God cannot exist and cannot intervene in His creation. But the theological trouble is that if you have God intervening over and over again, then why doesn’t He intervene to prevent vile genetic illnesses and the like? Better to keep God out of the equation or restrict His activities to salvation history, like the Resurrection — my point was simply to see how we can get God, given the randomness of Darwinian evolution.

  3. OrangeMath says:

    Great assignment introduction! Truly world class. It would be expected that essays written in response would include details on the work of Prigogene, a Nobel winner. The current “niche” concept is shorthand for far-too-complex, thermodynamic concerns. Too keep it simple, a biological niche is a metastable state — like a marble on a tabletop. Unfilled niches are tabletops with nothing on them — yet!

    • Michael Ruse Michael Ruse says:

      Thank you. Of course there was much more I could have talked about, but any experienced teacher knows that trying to say too much is as bad as saying too little. I defy anyone to talk about Prigogene at a level that a general audience could follow — if you can, let me know and I will be on the front row.

      • OrangeMath says:

        OK. I’ll try. “While this is actually multi-dimensional; let’s just stick to x & y. (draw on a white board, several line segments parallel to the x-axis at various ys. Then paint a stick figure of a person on one and a bug on another.) “There are many places where an organism can sustain itself, but finding those places is hard. Not all are occupied. It’s possible that we could jump to another level, but what’s the pathway? What’s the reactions necessary? A Nobel winner by the name of Prigogine addressed this in his ‘chaos theory.’ Funny story: when Stanford decided to become a world-class university in the early 1960s, the school worked very hard to get him to move. No dice. Everyone knew he was going to get the Nobel a decade before he did.”

  4. Shaikh Raisuddin says:

    Anthropocentrism is a category mistake used to make meaning out of the physical world. Mind is a social-implant. The direction of evolution depends upon the direction of the super system. (https://www.linkedin.com/pulse/human-mind-artificial-shaikh-raisuddin)

  5. SPM says:

    It seems difficult to get away from the idea of direction, even from a secular standpoint, in part because we (at least in the West) have been accustomed for so many centuries to thinking of history as linear, whether or not it goes anywhere predictable. And evolutionary theory only seems to strengthen that idea — if not of linear development, then from tree trunk to branches and not the other way around.

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