Over at that hilarious goldmine of accommodationism, Francis Collins’s BioLogos website (generously supported by The Templeton Foundation, they have posted an answer to the question, “Did evolution have to result in human beings?” Now if you know anything about this history of faith/science accommodationism, you know that the answer has to be “yes”, at least if you construe the question to mean “Did evolution have to result in a rational, highly intelligent being that was capable of apprehending and worshiping its creator?”  If God is running the evolutionary process, as the accommodationists maintain, then the evolution of humans (who are, after all, the goal of this process — the one species made in God’s image) could not have been left to chance.

And so, religious biologists like Kenneth Miller and Francis Collins, and “science-friendly” theologians like John Haught, have maintained in their writings that evolution would inevitably have coughed up an intelligent rational creature like Homo sapiens.  In other words, contrary to the assertions of Stephen Jay Gould, if we re-ran the tape of life, something humanlike would always appear.  Religious apologists always contend that the evolution of what we will call “humanoids” was not a continent process: it was built by God into the very fabric of evolution.

Of course, this is not a scientific belief.  For one thing, it makes humans different from other creatures.  The faithful don’t go around maintaining that the evolution of squirrels or cockroaches was an inevitable outcome of the evolutionary process, because according to Scripture God didn’t make rodents of insects in His image.  So God stuck his hand in, somewhere, to make humanoids appear.  That is creationism, pure and simple.  Or, he designed the process with the foreknowledge that humans would appear, which is also creationism, since no evolutionist really thinks that the process was jerry-rigged from the outset to produce certain life forms.

Second, if you do believe in a naturalistic and materialistic process of evolution in which God didn’t interfere, then the appearance of humans doesn’t seem likely at all — and certainly not inevitable.  Higher intelligence and rationality evolved only once, so it certainly isn’t something like eyes (whose morphology evolved independently dozens of time).  The idea that “convergent evolution” shows that humans were inevitable is deeply fallacious.

Yet BioLogos uses this argument — a favorite of the religious paleontologist Simon Conway Morris –to show that (surprise!) something like humans WAS inevitable in evolution.  After disposing of Gould’s contingency argument, they then approvingly reiterate Conway Morris’s “convergence” argument:

Humans: Inevitable, Intentional

Simon Conway Morris presents a different perspective, arguing humans, or a human-like species, are actually an inevitable part of evolution.  Morris is not proposing a different mechanism for human evolution, merely a different observation of its possible outcomes.  Morris would agree that any slight difference in the history of human DNA would result in a different evolutionary path.  Unlike Gould, however, Morris argues each of those possible pathways would inevitably lead to something like the human species.  Morris writes:

“The prevailing view of evolution is that life has no direction — no goals, no predictable outcomes. Hedged in by circumstances and coincidence, the course of life lurches from one point to another. It is pure chance that 3 billion years of evolution on Earth have produced a peculiarly clever ape. We may find distant echoes of our aptitude for tool making and language and our relentless curiosity in other animals, but intelligence like ours is very special. Right?”

“Wrong! The history of life on Earth appears impossibly complex and unpredictable, but take a closer look and you’ll find a deep structure. Physics and chemistry dictate that many things simply are not possible, and these constraints extend to biology. The solution to a particular biological problem can often only be handled in one of a few ways, which is why when you examine the tapestry of evolution you see the same patterns emerging over and over again.”

The patterns Morris mentions are also referred to as convergences in the evolutionary process.  In his most recent book, Life’s Solution, Morris gives many examples of physical traits or abilities found repeatedly among different species.⁵ Normally, such similarities are understood asthe result of common ancestry.  However, the species in Morris’s examples are known to be distantly related.  In many cases, not even these species’ common ancestor shared the same trait.  The implication is that several different species have independently developed similar traits.

The examples of convergence range across many levels of biology.  One popular and straightforward example is the human eye.  It turns out that several other species share a nearly identical visual system to that of the human eye, including the octopus.⁶ However, humans and octopuses have separate predecessors, neither of which shared this characteristic.  Two very different evolutionary paths arrived at the same visual system.  If Gould’s supposition is correct, and there was an infinity of other possible outcomes, then this example of convergence is all the more improbable.  Morris’s argument, conversely, is that the laws of nature allow for only a few solutions to any particular problem.  It appears the eye has developed independently at least seven times over the course of evolutionary time.

Human Significance

To see evidence for human significance, one need only consider Morris’s examples of convergence for many of the traits that are particularly relevant for human-like beings.  These examples include basic senses like balance, hearing and vision, as well as highly advanced features like the human brain.  Morris argues that evolution does not pose any threat to human significance.  Characteristics such as a large brain capable of consciousness, language and complex thought would inevitably have to emerge from the evolutionary process. Morris writes:

“Contrary to popular belief, the science of evolution does not belittle us.  As I argue, something like ourselves is an evolutionary inevitability, and our existence also reaffirms our one-ness with the rest of Creation.” ⁷

The exact anatomical features of this ultimate sentient being might not be precisely specified by the evolutionary process, however.  This thought can be unsettling to anyone who imagines our particular body plan is part of the imago Dei, or image of God. Despite the marvelous paintings in the Sistine Chapel, there is no reason to think that God the Father has a physical body that looks like ours.

God’s Sovereignty in the Evolution of Humans

Belief in a supernatural creator always leaves open the possibility that human beings are a fully-intended part of creation.  If the Creator chooses to interact with creation, he could very well influence the evolutionary process to ensure the arrival of his intended result.  (See Question 14 about Evolution and Divine Action.)  Furthermore, an omniscient creator could easily create the universe in such a way that physical and natural laws would result in human evolution.  (See Question 19 about Fine-Tuning of our Universe.)

Although the unpredictable mutations of DNA can make any species appear entirely accidental, Simon Conway Morris also puts forward strong arguments in favor of the inevitability of creatures that have the attributes of humans.  From this perspective, it seems the evolutionary process itself might be geared toward human life.

So it goes. (By the way, have a look at the last paragraph of this page where BioLogos suggests that the evolution of humanoids ON OTHER PLANETS was  improbable. (As expected, they take this stand because theologists can’t see God sending Jesus careening from planet to planet to save every species of alien).

The Argument for the Inevitability of Humanoids is perhaps the most popular argument (ranking with The Fine Tuning of Physical Constants) used by accommodists to show that evolution and God are not in conflict.  But the argument is simply wrong.  Nobody can say with assurance that the evolution of humanoids was inevitable.  The only honest response is “We don’t know” (and I would add “what we know about evolution tells us that it was probably not inevitable.”)

I attacked this argument in my New Republic essay “Seeing and Believing,” and for those who haven’t read it, or who don’t wish to plow through the link to find it, I’ll reproduce it here. This was a review of two books, Kenneth Miller’s Only a Theory: Evolution and the Battle for America’s Soul, and Karl Giberson’s Saving Darwin: How to be a Christian and Believe in Evolution.

III.

In Finding Darwin’s God, his earlier book, Miller proclaimed a universal theism: “Remember, once again, that people of faith believe their God is active in the present world, where He works in concert with the naturalism of physics and chemistry.” Giberson clearly agrees. And where do they find the hand of God in nature? Unsurprisingly, in the appearance of humans.

Giberson and Miller assert that the evolution of humans, or something very like them, was inevitable. Given the way that evolution works, they claim, it was certain that the animal kingdom would eventually work its way up to a species that was conscious, highly intelligent, and above all, capable of apprehending and worshipping its creator. This species did not have to look perfectly human, but it did have to have our refined mentality (call it “humanoid”). One of Miller’s chapters is even titled “The World That Knew We Were Coming.” Giberson notes that “capabilities like vision and intelligence are so valuable to organisms that many, if not most biologists believe they would probably arise under any normal evolutionary process…. So how can evolution be entirely random, if certain sophisticated end points are predictable?”

Reading this, many biologists will wonder how he can be so sure. After all, evolution is a contingent process. The way natural selection molds a species depends on unpredictable changes in climate, on random physical events such as meteor strikes or volcanic eruptions, on the occurrence of rare and random mutations, and on which species happen to be lucky enough to survive a mass extinction. If, for example, a large meteor had not struck Earth sixty-five million years ago, contributing to the extinction of the dinosaurs–and to the rise of the mammals they previously dominated–all mammals would probably still be small nocturnal insectivores, munching on crickets in the twilight.

Evolutionists long ago abandoned the notion that there is an inevitable evolutionary march toward greater complexity, a march that culminated in humans. Yes, the average complexity of all species has increased over the three-and-a-half billion years of evolution, but that is because life started out as a simple replicating molecule, and the only way to go from there is to become more complex. But now complexity is not always favored by natural selection. If you are a parasite, for instance, natural selection may make you less complex, because you can live off the exertions of another species. Tapeworms evolved from free-living worms, and during their evolution have lost their digestive system, their nervous system, and much of their reproductive apparatus. As I tell my students, they have become just absorptive bags of gonads, much like the students themselves. Yet tapeworms are superbly adapted for a parasitic way of life. It does not always pay to be smarter, either. For some years I had a pet skunk, who was lovable but dim. I mentioned this to my vet, who put me in my place: “Stupid? Hell, he’s perfectly adapted for being a skunk!” Intelligence comes with a cost: you need to produce and to carry that extra brain matter, and to crank up your metabolism to support it. And sometimes this cost exceeds the genetic payoff. A smarter skunk might not be a fitter skunk.

To support the inevitability of humans, Giberson and Miller invoke the notion of evolutionary convergence. This idea is simple: species often adapt to similar environments by independently evolving similar features. Ichthyosaurs (ancient marine reptiles), porpoises, and fish all evolved independently in the water, and through natural selection all three acquired fins and a similar streamlined shape. Complex “camera eyes” evolved in both vertebrates and squid. Arctic animals such as polar bears, arctic hares, and snowy owls either are white or turn white in the winter, hiding them from predators or prey. Perhaps the most astonishing example of convergence is the similarity between some species of marsupial mammals in Australia and unrelated placental mammals that live elsewhere. The marsupial flying phalanger looks and acts just like the flying squirrel of the New World. Marsupial moles, with their reduced eyes and big burrowing claws, are dead ringers for our placental moles. Until its extinction in 1936, the remarkable thylacine, or Tasmanian wolf, looked and hunted like a placental wolf.

Convergence tells us something deep about evolution. There must be preexisting “niches,” or ways of life, that call up similar evolutionary changes in unrelated species that adapt to them. That is, starting with different ancestors and fuelled by different mutations, natural selection can nonetheless mold bodies in very similar ways–so long as those changes improve survival and reproduction. There were niches in the sea for fish-eating mammals and reptiles, so porpoises and ichthyosaurs became streamlined. Animals in the Arctic improve their survival if they are white in the winter. And there must obviously be a niche for a small omnivorous mammal that glides from tree to tree. Convergence is one of the most impressive features of evolution, and it is common: there are hundreds of cases.

All it takes to argue for the inevitability of humanoids, then, is to claim that there was a “humanoid niche”–a way of life that required high intelligence and sophisticated self-consciousness–and that this niche remained unfilled until inevitably invaded by human ancestors. But was its occupation really inevitable? Miller is confident that it was:

“But as life re-explored 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 we have, and capable of discovering the very process that produced it, the process of evolution…. Everything we know about evolution suggests that it could, sooner or later, get to that niche.”

Miller and Giberson are forced to this view for a simple reason. If we cannot prove that humanoid evolution was inevitable, then the reconciliation of evolution and Christianity collapses. For if we really were the special object of God’s creation, our evolution could not have been left to chance. (It may not be irrelevant that although the Catholic Church accepts most of Darwinism, it makes an official exception for the evolution of Homo sapiens, whose soul is said to have been created by God and inserted at some point into the human lineage.)

The difficulty is that most scientists do not share Miller’s certainty. This is because evolution is not a repeatable experiment. We cannot replay the tape of life over and over to see if higher consciousness always crops up. In fact, there are good reasons for thinking that the evolution of humanoids was not only not inevitable, but was a priori improbable. Although convergences are striking features of evolution, there are at least as many failures of convergence. These failures are less striking because they involve species that are missing. Consider Australia again. Many types of mammals that evolved elsewhere have no equivalents among marsupials. There is no marsupial counterpart to a bat (that is, a flying mammal), or to giraffes and elephants (large mammals with long necks or noses that can browse on the leaves of trees). Most tellingly, Australia evolved no counterpart to primates, or any creature with primate-like intelligence. In fact, Australia has many unfilled niches–and hence many unfulfilled convergences, including that prized “humanoid” niche. If high intelligence was such a predictable result of evolution, why did it not evolve in Australia? Why did it arise only once, in Africa?

This raises another question. We recognize convergences because unrelated species evolve similar traits. In other words, the traits appear in more than one species. But sophisticated, self-aware intelligence is a singleton: it evolved just once, in a human ancestor. (Octopi and dolphins are also smart, but they do not have the stuff to reflect on their origins.) In contrast, eyes have evolved independently forty times, and white color in Arctic animals appeared several times. It is hard to make a convincing case for the evolutionary inevitability of a feature that arose only once. The elephant’s trunk, a complex and sophisticated adaptation (it has over forty thousand muscles!), is also an evolutionary singleton. Yet you do not hear scientists arguing that evolution would inevitably fill the “elephant niche.” Giberson and Miller proclaim the inevitability of humanoids for one reason only: Christianity demands it.

Finally, it is abundantly clear that the evolution of human intelligence was a contingent event: contingent on the drying out of the African forest and the development of grasslands, which enabled apes to leave the trees and walk on two legs. Indeed, to maintain that the evolution of humans was inevitable, you must also maintain that the evolution of apes was inevitable, that the evolution of primates was inevitable, that the rise of mammals was inevitable, and so on back through dozens of ancestors, all of whose appearances must be seen as inevitable. This produces a regress of increasing unlikelihood. In the end, the question of whether human-like creatures were inevitable can be answered only by admitting that we do not know–and adding that most scientific evidence suggests that they were not. Any other answer involves either wishful thinking or theology.

Miller opts for theology. Although his new book does not say how God ensured the arrival of Homo sapiens, Miller was more explicit in Finding Darwin’s God. There he suggested that the indeterminacy of quantum mechanics allows God to intervene at the level of atoms, influencing events on a larger scale:

“The indeterminate nature of quantum events would allow a clever and subtle God to influence events in ways that are profound, but scientifically undetectable to us. Those events could include the appearance of mutations, the activation of individual neurons in the brain, and even the survival of individual cells and organisms affected by the chance processes of radioactive decay.”

In other words, God is a Mover of Electrons, deliberately keeping his incursions into nature so subtle that they’re invisible. It is baffling that Miller, who comes up with the most technically astute arguments against irreducible complexity, can in the end wind up touting God’s micro-editing of DNA. This argument is in fact identical to that of Michael Behe, the ID advocate against whom Miller testified in the Harrisburg trial. It is another God-of-the-gaps argument, except that this time the gaps are tiny.

Obviously, given that higher intelligence and rationality of the human type has evolved only once, the existence of convergence says nothing about whether these features would always appear.  In fact, the one-offness seems to imply otherwise.

What bothers me about this is, of course, that BioLogos is using the imprimatur of science (and the wonky ideas of Simon Conway Morris) to try to convince people that of course our evolution was inevitable.  This tactic is a favorite of BioLogos (and Templeton), for it tries to blur the boundaries between science and faith.  As scientists we can say nothing about the inevitability of humans except that it seems unlikely given its unique appearance.  Certainly one can say that the idea of evolutionary convergence is irrelevant here.

Please, BioLogos, stop making scientific arguments for God!