Essay:A Response to Locke's, "The Scientific Case Against Evolution"
This Article refutes the Claim of the Theory of Evolution being unfalsifiable by Popper's Falsifiability Criterion.
A Response to Robert Locke's, "The Scientific Case Against Evolution"
P. Wesley Edwards (updated 3-Feb-2006)
A reader recently forwarded a link to Robert Locke’s short article entitled The Scientific Case Against Evolution.1 The author, while claiming not to be a creationist, certainly writes in the curious even-evolutionists-now-realize style so common among creationist writers. The article, while not offering new arguments (and not pretending to) does do a good job of succinctly summarizing the current repackaging of the standard creationist themes, so it seemed worthy of a point-by-point response.
Locke’s first claim is that there have always been “distinguished scientists” of “impeccable credentials” who don’t agree that evolution has been proved. Strangely, Locke’s examples are Richard Owens and, curiously, Stephen J. Gould. Owens was indeed a distinguished scientist — back in the 19th century. He entered medical school in 1824. If the credibility of a scientific viewpoint in the 21st century can be established by citing the particular views of scientists living hundreds of years ago, then some very strange ideas would suddenly become “credible.” Indeed, by reference to the past I could argue that many distinguished scientists refuse to accept the structure of the atom; and if I go back just a bit more I could even argue that many distinguished scientists refuse to accept the roundness of the Earth, or even the fact that the Earth is not the center of the universe. Certainly, when one wants to give credibility to an idea by showing how mainstream its supporters are, one would do better by referring to the mainstream of modern science. Darwin’s genius, like Copernicus', was not merely that his ideas were revolutionary in his time and supported by the evidence available to him, but that they were also overwhelmingly confirmed by future discoveries, and even by future sciences, becoming not only mainstream, but basic, introductory knowledge for students of the fields.
As for Steven J. Gould, I can do no better than to let him speak for himself: "…it is infuriating to be quoted again and again by creationists—whether through design or stupidity, I do not know—as admitting the fossil record includes no transitional forms.”2
Of course, there are many, many examples of transitional forms, some of which Gould cites, and many others readily available from any number of academic sources. It is important to recognize that this anti-evolutionist appeal to “lack of intermediates” utterly depends on there being no intermediates whatsoever. If intermediates are found at all — even if there are not as many as some of the more extreme gradualist models might suggest — then the criticism is falsified. As Gould writes,
The supposed lack of intermediary forms in the fossil record remains the fundamental canard of current antievolutionism. Such transitional forms are sparse, to be sure, and for two sets of good reasons — geological (the gappiness of the fossil record) and biological (the episodic nature of evolutionary change, including patterns of punctuated equilibrium, and transition within small populations of limited geographical extent). But paleontologists have discovered several superb examples of intermediary forms and sequences, more than enough to convince any fair-minded skeptic about the reality of life’s physical genealogy.3
Gould goes on to describe many of these examples, and elsewhere he even walks through the richly detailed step-by-step, gradual evolution of the whale as revealed by recent fossils4. Gould’s “punctuated equilibrium” contribution is simply to point out that evolutionary change does not always proceed at a constant rate. Nonetheless, numerous fossil sequences do show transitionals grading continuously between successive species within the same taxon, and crossing from one taxon into another. The mammal-to-reptile transition is richly documented, as is the amphibian-to-reptile, and the fish-to-amphibian. As for transitions between closely related species, one need go no further than the well-known intermediates between humans and our recent common ancestor with Great Apes (e.g. Homo habilis, Homo erectus, and the various australopithecines), whose features are as intermediate as you can ever hope to imagine. Indeed, it’s puzzling to see their intermediate nature simply denied by antievolutionists, whose rejection seems based on forcing discrete criteria onto what is essentially a continuum. This tactic simply defines intermediates out of existence, meaning that, a priori, nothing would count as an intermediate. It is as if I were to claim that color does not exist in a continuum, and when someone showed me something between, say, red and orange, I simply declared it to be in one category or the other (e.g., "It looks more red than orange, so it's red").
It is instructive to ask the antievolutionist in such situations for an example of what they would accept as an intermediate — even hypothetically. Typically, they do one of the following: (1) describe something that is completely inconsistent with evolution, and that if it were actually found, would tend to disprove, rather than prove, evolution; and (2) describe a creature that is intermediate in every feature, which is also not expected under evolutionary theory. For example, Lock’s comments on the lungfish suggest that he thinks intermediates should be intermediate in all characteristics. This is simply false. Intermediates consistent with the actual theory of evolution are precisely what we do find in abundance.
It is very important to understand the difference between evidence that shows that descent with modification occurred (that is, that all life is related somehow through common descent in a “tree of life”) and evidence for or against particular mechanisms and tempos by which it occurred. I refer you to my article on evolution at Evolution: Converging Lines of Evidence for more on this critical distinction, which antievolutionists, including Locke, repeatedly ignore. These antievolutionists repeatedly confuse the mainstream scientific criticisms of some theory of mode or tempo (e.g., Gould’s attack on steady-state gradualism) as an attack on evolution itself (i.e., descent with modification). This is worse than false, and represents a serious misreading of fundamental evolutionary concepts. Supposed "critics" of evolution (like Gould) slap their heads at this, and write pointed rebuttals like the one cited earlier, but they are simply ignored. Contrary to what Locke cites Denton as saying, the fossil record has amassed far more evidence than is necessary to prove that all life is in fact related through common descent. None of this evidence puts descent with modification in doubt at all—quite the contrary: the number and range of transitional forms is now quite large and still growing. But the proof that evolution has occurred goes far beyond the fossil record or any one line of evidence (see Evolution: Converging Lines of Evidence).
Locke goes on to say, “The problem with this theory [punctuated equilibrium], which is too complex to go into in detail here, is that while it explains away the non-existence of small gradations, it still requires there to be large ones (the individual spurts) and even these aren't in the record.” It’s unclear what he means by “individual spurt” since individuals don’t evolve, populations do. In any case, this is a rather egregious misreading of Gould. As my earlier quote shows, Gould, and evolutionists in general, hardly believe in the “non-existence of small gradations.” Gould cites many of his own examples, which barely scratch the surface of the examples readily available. And about his theory requiring large gradations, Gould goes on: “Continuing the distortion, several creationists have equated the theory of punctuated equilibrium with a caricature [that] major transitions are accomplished suddenly by means of ‘hopeful monsters.’”5 Gould then goes on to quote Duane Gish as claiming that Gould believes a reptile laid an egg from which a fully formed bird emerged, to which Gould remarks, “Any evolutionist who believed such nonsense would rightly be laughed off the intellectual stage.”6 Locke is not clear as to how large a “spurt” he is referring to, but the idea that Gould believes that significant evolutionary change occurred through such sudden jumps is simply false. (Perhaps Locke is misunderstanding the significance of the uncontroversial fact that some genes have a more dramatic effect on morphology than others, and these genes can also be affected by natural selection.) Punctuated Equilibrium simply argues that the tempo of evolution is often relatively rapid when speciation is occurring, since it argues that speciation often occurs when small groups are isolated, with stasis being the rule otherwise. But “rapid” or “sudden” here is used in the geological sense, not in a literal everyday “overnight” sense of the word. By “rapid” Gould means tens of thousands of years. But since a single species can be depositing fossils for many millions of years, the speciation period can represent considerably less than 1% of that time span. And despite that, we still have many examples of transitional fossils.
Locke’s comments on computers reveal a misunderstanding of cladistics and neglect of a vast literature showing the incredible contributions to, and logical validation of, evolutionary theory that computers have provided. The burgeoning fields of artificial life, genetic algorithms, and evolutionary programming exist only because natural selection and descent with modification are logically coherent concepts and describe highly creative processes. (If Darwinism were the tautology some creationists claim it to be, then one couldn’t simulate it in software and expect it to do anything.) These sciences depend on creating a virtual world where neo-Darwinism can be instantiated. This is done by creating the software equivalents of genes, random mutation, random genetic recombination, and environmental forces that affect the relative “fitness” of the resulting gene combinations. Famous examples of these include “Tierra,” and “Polyworld.” (In Tierra, parasitic life forms unexpectedly evolved to the utter astonishment of Tierra's programmers. Even more astonishing was the evolution of an immune response to these parasites and an ensuing “arms race” between these emergent species.)7 Such techniques are even now being used in industrial applications to allow evolution to “design” solutions to engineering problems, like coming up with efficient aircraft wing shapes. These facts refute in a stroke all attacks on evolution based on supposed logical incoherence or meaninglessness (such as the circularity/tautology objection). In my other evolution article, Evolution: Converging Lines of Evidence, I discuss cladistics in more detail, and show why Locke is quite mistaken when he claims that an evolutionary tree is only the result of “pattern craving” human minds.
Locke also states that, “…if different species have common ancestors, it would be reasonable to expect that similar structures in the different species be specified in similar ways in their DNA and develop in similar ways in their embryos; this is frequently not so.” Without examples, it’s difficult to understand what he is asserting. For example, all life shares a common ancestor—if you go back far enough. If two species share a recent common ancestor, such as modern humans and chimpanzees do, then much is indeed “specified in similar ways,” and “develop in similar ways in their embryos.” But where the common ancestor is much further back, the expectation naturally changes. Indeed, the case of the evolution of the whale is one of a creature who can trace its ancestry onto land, and then, if you go back further still, back to the sea yet again. Does this mean that its “fins” should be like a fish’s fins because all life shares a common ancestor? The answer, of course, is no. Locke’s comment here seems to reveal a misunderstanding of the significance of homologous and analogous morphologies in evolutionary theory. Indeed, it is evolution that predicts and explains what we do in fact see in the natural world. This subject is also covered in more detail in the previously mentioned article.
Locke’s comments on the horse are a bit vague as well. He seems to be saying that the earliest horse and the modern horse are too similar to each other, and so showing a gradual transition between them doesn’t prove much, yet he seems to question the transitional evidence regardless. Of course, the earliest “horse” is a little, terrier-sized forest dweller called Hyracotherium, which lived some 54 million years ago (mya). Is he saying it is a horse in order to be able to declare that the transition evidence doesn’t prove much? Whether you choose to call Hyracotherium a horse or not, presumably one still needs to explain the process by which it so dramatically changed over those 54mya.
When Locke says, “And even the emergence of one species from another has never been directly observed by science,” he reveals a serious misunderstanding of the scientific method itself — as it applies to all of science. Surely, science is more than simply reporting what we directly observe; in fact, science is all about using what we can see to predict and describe what we cannot see.8 For example, no one has “observed” electrons orbiting the nucleus, or seen the inside of the sun, or even seen germs actually making a living human sick (we only observe the illness at work under a microscope in a lab). Regardless, we can know these models describe reality when the models make successful predictions (e.g., “if the atom has structure x, then i, j, and k should be true — are they?”). Locke’s is the type of criticism that, if accepted, would require our throwing out not just evolution but much of physics, astronomy, geology, and the other physical sciences, not to mention our rules of evidence in courts of law. Indeed, though I would suspect Locke and others using this argument do not realize it, it is an anti-reason argument. If direct observation were the only way we could be sure of anything, then our legal system would be in jeopardy, since the only evidence acceptable would be eyewitness testimony — no genetic, no fingerprints, no hair, no physical evidence whatsoever, since none of that bears on direct observation of the crime actually happening. Clearly, there is something wrong with this line of criticism. Yet, despite the fact that direct observation of an event is not necessary in order to know that an event really happened, speciation has been directly observed in the lab on multiple occasions.
Locke also brings up a classic of creationist argumentation: the “can’t get there from here” charge. This is illustrated by the “half of a wing,” or “half of an eye” example. Sometimes this is called the “irreducible complexity” argument. All forms of this argument are based on a serious confusion as to what evolutionary theory is actually saying. First, it’s important to understand why half wings are not predicted by evolution. In fact, if we ever did find evidence of a species with what amounted to modern wings but “chopped in half” (as if waiting to “evolve” the other half), then evolutionary theory would actually have a big problem on its hands.
Natural selection operates only in the immediate, local environment—it has no intelligence, no purpose, and no ability to see even one generation into the future. Novel gene combinations, additions, or mutations, will spread in a population only if they increase the odds (even slightly) that the affected offspring will live long enough to make babies. This is just a mathematical property of the system: Since offspring with these “helpful” genes are more likely to make babies, more babies in the next generation will have these genes—since they inherit their genes from their parents. And the number of babies with these genes will keep increasing in each generation as long as these genes continue to be helpful. (This lack of foresight in natural selection is also why evolution cannot “go back” and redesign something; it can only work with what is at hand.)
This means that useless partial stumps of would-be “future” wings, or anything else, would get in the way, as so be selected against. So, when we do see useless appendages (like the vestigial leg bones inside some snakes), they represent the withering away of the creature’s past features that are no longer useful; they don’t represent the “embryo” of some future characteristic. As a result, we expect that all life forms, ancient and modern (which includes what we call “transitionals”) to be generally well adapted to their environments. It’s not as if today is the day that all species were working toward and are now finally “done” evolving, while in the past they were only “half way” there. There is nothing special about now as opposed to the distant past or the distant future. In the distant future, species that appear “complete” to us now will probably be described as transitional by future paleontologists—they might even be talking about our species.
So what about birds and their wings? How can they have been adapted to their environments in the past if they couldn’t even fly? The answer is that the ancestors of birds were adapted to a completely different environmental niche than their modern-day descendents, one that had nothing to do with flying. Characteristics that would later support flight, like feathers, originally appeared for a completely unrelated reason, perhaps for something like insulation—a purpose that had immediate benefit. Remember, potential future usefulness doesn’t count. Basically, a new incipient structure can arise (a) because the genes that produce it are being selected for a completely different reason — generating the incipient structure like a side effect, which is then able serve an unrelated purpose of its own; (b) because it directly intensifies some ability or function; or (c), because the structure was used for one thing but is now being used for something else, which makes it subject to completely different selective forces. Note that this predicts that creatures should be readily found that are inefficient in their designs, which is easy enough to do (look at a panda’s “thumb” or the bizarre embryological processes that I cite in my other article).
To clarify this very important point, let’s use an analogy: Think of the hypothetical “evolution” of a brick arch-bridge. First, there’s no need for a bridge, there is just a pathway. But farms on each side of the pathway want to keep their cows in, so they put up fences. A mild earthquake creates a small crack, but people can still jump over it easily enough. But the crack widens over time, so some fence planks that are no longer needed are taken down and laid across the crack. As the crack widens, the planks begins to sag, so scattered bricks that have fallen from passing wheelbarrows are collected and stacked in columns beneath it for support. Initially, just a few bricks in single column are sufficient, but over time the crack continues to widen and deepen. As a result, gradually more and more stacks of bricks are added so that the supports eventually form a wall, like a dam. Eventually, increasingly heavy water flow through this ever deepening fissure knocks out some of the lower bricks; however, the bridge doesn’t need to be repaired because the upper bricks that used to be supported by these lower ones have now become equally well supported sideways by their ever-pressing neighbors. The lower bricks from the center of the span are allowed to wash away leaving an arch connecting either side of the creek. A creationist then comes along and points out that this must have been designed and built in one event as an arch bridge; after all, an arch bridge is “irreducibly complex”: what good is half and arch? Indeed, what could have held up half an arch? Well, in this case there never was half an arch. There were intermediate structures that served other purposes and worked well enough in their day. At each point in its history the bridge structure was "complete." At each step minor steps were taken for immediate needs using only the materials that were on hand at the time. And at no point was there a grand design, or an end game in mind.
This crude analogy shows how evolution can inadvertently create what amounts to “scaffolding,” which can disappear when it is no longer needed, leaving a free-standing structure that would collapse if any of its current parts were missing—creating what appears to be an irreducibly complex structure. This would apply not only to morphological structures, but to chemical processes as well. This explanation is not revolutionary, and can be see at work in the fossil record in cases such as the formation of mammalian ear bones from parts of the reptilian jaw.
Locke’s comments regarding the findings from microbiolog (i.e., protein comparisons) are difficult to make sense of, unless he misunderstands what he is describing. Surely, Locke understands that all proteins, and by extension all genes, are not expected to diverge equally in proportion to evolutionary distance. The degree to which different proteins can diverge is a function of the nature of the protein and its role. Some proteins can fulfill their functions with a wide variety of amino acid substitutions (which trace back to gene substitutions), others cannot. Those that cannot would not be expected to show much change at all, even in “deep time,” and their conservation over time (and therefore across widely disparate species) is expected; it is a result of what is called “purifying selection.” However, those proteins that are functionally unconstrained do accumulate differences, and do so in proportion to their evolutionary distance—it is this fact that is explained only by evolution: Why would functional, unconstrained proteins diverge only in proportion to evolutionary distance? The evidence from microbiology here is truly vast, and conclusive on its own, and I mention some of the most powerful of it in my other article.
The “can’t get the ball rolling” argument that Lock makes is, of course, irrelevant in a very important sense: The evidence that life shares a common ancestor is completely independent of any theory as to how the root of that tree of life “got started.” Indeed, many evolutionists are Christians, or other types of theists, and believe that God got the ball rolling. Nonetheless, there are very plausible accounts (Nobel Laureate Christian de Duve has an interesting one in his book, Vital Dust9), though not enough evidence yet exists to conclusively support one plausible path over another. Telling experiments, such as Stanley Miller’s, hint at pieces of the answer by showing, for example, how natural inorganic processes can form the amino acid building blocks of life — spontaneously. No specific path may ever be found, but the evidence that evolution occurred is quite independent of that question. We can know that it happened without knowing all the detail of how it happened, and the evidence that it happened is overwhelming and conclusive.
Locke’s call for intermediates is also quite misplaced here. Archaic bacteria have been found and their genetic differences from the rest of the living world are as profound as one would expect under the evolutionary model. What’s more is that these ancient life forms find oxygen utterly poisonous. We know from geological evidence that huge periods of our past were oxygen free. This fits well with the idea that an oxygen-rich atmosphere would have destroyed that early life and any earlier “proto-life.” When these early bacteria multiplied beyond a certain point, their own waste – oxygen – killed most of them off from everywhere except their current exotic, oxygen-free environments; others not only learned to tolerate oxygen, but also got to a point where they needed it. The bottom line is that the world is a very different place now than it was then. The presence of oxygen would be highly corrosive to the kinds of complex molecules that might represent the intermediates between life and non-life, dissolving them almost immediately. As in our arch-bridge example, the “scaffolding” that such prebiotic intermediates represent may well have long since washed away, and the world is now far too poisonous (oxygen rich) a place for them to ever appear again. All we may be able to do now is infer their existence. But such inferences can be as conclusive as the inferences that tell us of the structure of the atom, or the guilt of a criminal in a court of law.
Locke also makes a passing reference to the “odds” of any of it happening by “chance.” When he uses the phrase, “too complex to have been thrown together by any known non-living chemical event,” he demonstrates a common misapplication of probability theory to this subject. For a discussion of the flaws in such misapplications of probability, I refer you to my article on Complexity, Probability, and God.
Locke also mentions Karl Popper. I can only assume Locke is unaware that Popper’s critique was never of descent with modification, but of natural selection, and he admitted that he was mistaken even in that once he learned a bit more about the subject. Popper has always said that Darwin’s core thesis — that all life is related through descent with modification — was not only testable, but was the most successful explanation of all the data. Indeed, he considered Descent with Modification to be “historical fact.”10 Locke’s sources are seriously misinformed. Regarding natural selection, Popper retracted his tautology charge, pointing out that natural selection “can be so formulated as to be far from tautological.”11 Popper was of course right that some people do come up with untestable natural selection stories (Gould called these “just-so” stories) about how some physical feature or other came to be. Misapplication, or untestable speculation, based on the concepts of an otherwise proven theory is not evidence against the theory anymore than making untestable speculations about how some physical event may have happened, amounts to evidence against physics. To suppose that is does is to suppose these speculations provide the evidence for the theory, which of course, they do not.
Ironically, it is creationism that fails Popper’s falsifiability criteria, not evolution. In my evolution article I make clear how evolution (descent with modification) is repeatedly falsifiable and yet resoundingly passes these tests. Creationism, however, isn’t even a theory. (As someone once put it, “It’s not even wrong.”) It seems little more than a set of mutually contradictory and ill-informed attacks on evolution. Stripped of this negative content, it has no substantive positive content of its own beyond saying, “things are the way they are because God must have wanted it that way.” What does that predict? How does a scientist use such a "theory" to gain additional insights in the lab or in the field? What could conceivably count as evidence against it?
I cannot bring myself to let Locke’s analogy between evolution and Newtonian physics get by. Certainly, the evidence that supported the validity of Newtonian physics was vast and convergent, just as it is with evolution. It is also true that Newtonian physics was later discovered to be a special case of a more general theory of physics, called relativity. But this in no way suggests that Newtonian physics was falsified. What it does mean is that Newton’s formulas and theories remain true over the domain of problems to which the theory is applied, and while he imagined that it would work in even the most extreme circumstances, it turned out other factors become more dominant in those extremes. Such advancement is what science is all about: building on, rather than erasing, the work of others. Indeed, we use Newtonian mechanics today, and not relativity, to put people on the moon, to design our airplanes, our cars, our satellites, and our buildings. If evolution were found to be a special case of a broader theory in the same way that Newtonian mechanics was, then it would not be much of a cause for antievolutionist celebration.
I have to conclude that Locke’s “Scientific Case” not only fails to make its case, but is not very scientific. His claim of a “major trend” in biology against evolution would come as a surprise to biologists the world over, and his evidence to support this claim is either hundreds of years old, or is based on rather gross (though, I’m sure, unintentional) misrepresentations, of both science and individual scientists. It brings up old, unoriginal arguments that have long-since been discredited—arguments based on misrepresenting scientists’ views, misrepresenting evolutionary science, and even misrepresenting the scientific method itself. Indeed, my Gould quotes date back to the mid 1980’s (Popper’s retraction dates back to the 1970’s) and yet almost a quarter century later we continue to see antievolutionist / creationist writings misquoting and misrepresenting his work in exactly the same way they did back then, without even a passing acknowledgement of Gould’s repeated and forceful refutations of these same misrepresentations of his hard work. (Even if Locke is not a creationist or “antievolutionist,” he uses and draws upon sources that use their discredited arguments and misrepresentations.) Such is yet another reason why creationism is not considered science at all.
- Robert Locke, “The Scientific Case Against Evolution,” 5/2/2004, <http://www.godandscience.org/evolution/locke.html>
- Steven J. Gould, “Evolution as Fact and Theory,” in Science and Creationism, ed. Ashely Montegu (New York: Oxford University Press, 1984), p. 124.
- Steven J. Gould, Dinosaur in a Haystack: Reflections in Natural History (New York: Random House, 1995), pp. 359-376.
- Gould, “Evolution as Fact and Theory,” p. 124.
- A good introduction to the field is Steven Levy, Artificial Life: A Report from the Frontier Where Computers Meet Biology (New York: Random House, 1992).
- Excellent discussions of this point in Philip Kitcher, Abusing Science: The Case Against Creationism (Cambridge: MIT Press, 1993).
- Christian DeDuve, Vital Dust: The Origin and Evolution of Life on Earth (Basic Books: New York, 1995)
- Quoted in Robert T. Pennock, Tower of Babel: The Evidence against the New Creationism (Cambridge: MIT Press, 1999) p. 100.