Jerry Coyne, a well-known biologist at the University of Chicago, is also one of the outspoken militant atheists (more on that later), and his book Why Evolution Is True is a title likely to raise your blood pressure, with a name seemingly smacking of propaganda more than science. Here, one needs to understand the scientist’s conception of truth: “All scientific truth is provisional, subject to modification in the light of new evidence. There is no alarm bell that goes off to tell scientists that they’ve finally hit on the ultimate, unchangeable truths about nature” (p. 16). Coyne explores the evidence currently supporting the scientific judgment that evolution is a provisionally true framework for understanding the natural history of organisms. Indeed, the history of evolutionary theory is no different than that of any other major scientific theoretical framework–one of constant modification and refinement as we learn new things.
The breadth and clarity of Coyne’s explanation and discussion of the evidence supporting evolution is impressive. Christians who have even a passing interest in science should give what he has to say careful, prayerful reflection. However, the significant level of Christian misunderstanding of evolution makes reflection on the theory difficult. Coyne’s book is helpful for addressing the distorting myths so characteristic of Christian discussions of evolution. In Part 1 of this review, I want to lay out some of the key myths and indicate how Coyne’s discussion can help Christians get a more accurate understanding of what evolution says and does not say. In the remaining parts, I’ll explore Coyne’s problematic approach to science and faith.
Myth: Random Variations Are Uncaused
Christians (and most atheists) often characterize evolution as excluding God because the variations at the heart of evolutionary theory are “random” or “unguided.” They take such terms to imply that genetic variations are uncaused or ungoverned. However, as Coyne explains, “The term ‘random’ here has a specific meaning that is often misunderstood, even by biologists. What this means is that mutations occur regardless of whether they would be useful to the individual” (p. 118).
Consider an analogy with games of chance. Dice don’t land snake eyes because that would benefit the gambler. Yet there is an underlying set of causes as to why the dice landed snake eyes on that particular roll (even though we refer to the outcome as random or undirected). Similarly, there are underlying causes as to why particular offspring in a population of organisms received the particular genetic variations they did.
Moreover, the biological notion of random or unguided mutations doesn’t even rule out God as the possible cause of the variations. All biologists mean by such terms is that the underlying causes are left open by evolutionary theory because mechanisms like natural selection can work with any variations handed to them, whether those variations are due to genetic copying, cosmic rays or God. Consider the dice analogy again. That the dice landed snake eyes on this particular throw is fully consistent with there being an underlying law governing the dice or that God somehow determined the particular outcome of the throw (the latter idea lies behind the Old Testament practice of casting lots). Similarly, that some organisms in a particular population received a particular genetic variation increasing their likelihood of surviving and reproducing is fully consistent with there being an underlying law governing genetics (a reflection of the regular, ongoing activity of God), or that God somehow determined the particular variation through supernatural intervention.
Myth: Everything in Evolution Happens by Chance
It’s typical of Christian discussions to attribute everything in evolution as due to chance. In contrast, as Coyne points out, although there is a technical sense in which a variation in an organism is random, “the filtering of that variation by natural selection that produces adaptations...is manifestly not random” (p. 119). Variations received by organisms are indifferent to the needs of the organism, but the filtering out of harmful variations is anything but random. That filtering–natural selection–promotes survival and reproduction, a clearly nonrandom outcome.
Myth: Evolution Works Solely Through Natural Selection and Random Variations
Most all Christian discussions of evolution assume that the theory only uses natural selection acting on random variations to explain biological change. I suspect this overly narrow view of evolution is largely inspired by Richard Dawkins, who early in his career described evolution as working through only natural selection. Although Coyne focuses primarily on natural selection, he helpfully points out that there is much more to evolution than natural selection acting on random variations (e.g., pp. 3, 13, 122-124, 170, 177).
Darwin thought that natural selection was the most important evolutionary mechanism, but stressed that there were other mechanism as well (e.g., sexual selection). Contemporary evolutionary biologists also explore components of evolution beyond natural selection. Genetic drift, for example is an important component in evolutionary theory (particularly at the molecular level). Exaptation is another important component in the production of new structures with new functions. It occurs when a feature that was originally adapted by natural selection to perform a particular function is co-opted for a different function and then modified by natural selection with respect to this new function. Consider feathers. It’s now known that most all of the carnivorous theropod dinosaurs (e.g., Deinonychus, Velociraptor, T. rex) were covered with feathers. Feathers probably arose under natural selection for thermal regulation of body temperature (the fossil record reveals feathered, nonflying dinosaurs appearing long before feathered flying creatures arise). It is likely that feathers then were co-opted for flight (probably gliding first with powered flight coming later), a completely different function than their original natural selection history of development. Natural selection would then have begun to refine the feathers of flying organisms for improved flight capabilities.
Myth: Evolution Always Optimizes
Almost all Christian critiques of evolution are aimed at an extreme optimizing interpretation of evolution: Natural selection acts to optimize species traits for their particular environment. However, it’s been well known for a long time that this interpretation of evolution is seriously flawed (this is one reason why most all creationist and ID attacks on evolution are unconvincing). As Coyne explains, “Natural selection does not yield perfection–only improvements over what came before. It produces the fitter not the fittest” (p. 13).
Darwin argued that evolution doesn’t optimize the traits of organisms. Rather, he emphasized over and over again that evolution produces just-good-enough solutions for making a living in particular ecological niches. For instance, the key idea of natural selection is that some organisms have a slight differential advantage in reproduction due to some variation in a trait that they received at birth, and this slight advantage is all that may be needed to more deeply penetrate an ecological niche successfully with no further modifications needed.
Myth: Evolution Is Necessarily Always Improving Organisms
Another common misconception of evolution in Christian circles is that organisms are constantly improving under evolution. Coyne helpfully clarifies that evolution doesn’t necessarily imply organisms are constantly improving (e.g., pp. 4, 13, 131-136). Darwin argued that evolution’s just-good-enough solutions were sufficient for surviving well in an ecological niche.Furthermore, there is nothing about evolutionary theory implying a necessary progression from simple to complex life forms or from lower to higher life forms.
What evolution produces are different life forms, each shaped to survive and reproduce in its ecological niche. Therefore, one should expect to see stasis in ecological niches where evolutionary pressures are minimal (e.g., sharks haven’t changed much in 25 million years). In niches where evolutionary pressures are high, such as the human body’s immune system combined with our repertoire of antibiotics, one should expect to see changes in the microorganisms causing disease and this is exactly what we do see (e.g., pp. 130-132). Moreover, there is nothing in evolutionary theory implying that species cannot devolve from more complex to simpler forms if that’s what gives them a better purchase on penetrating deeper into a particular ecological niche (e.g., organisms slowly losing their eyes when they live for many generations in dark caves).
Similarly, there is nothing in the theory implying common ancestors in the past should be driven to extinction by evolved successor species (as far too many oversimplified Christian critiques of evolution maintain). That fate depends on whether the ancestor and successor species end up competing for the same resources in the same ecological niche. If the successor species gains abilities to exploit different resources within the same ecological niche, there is no reason to expect that the ancestor species would die out or be driven to extinction.