On the Origin of Stasis (Part III)

Charles Darwin made the concept of major evolutionary change plausible by convincing scientists that natural selection could account for the appearance of design in nature. [Horan] He would never have considered evolution a fact without a plausible theory of how it could occur. The very title of his book reflects the importance of an evolutionary mechanism. Although much evidence has been cited in favor of macroevolution, as it had been prior to 1859, such evidence in Darwin's own opinion would be unsatisfactory without a mechanism:

In considering the Origin of Species, it is quite conceivable that a naturalist, reflecting on the mutual similarities of organic beings, on their embryological relations, their geographical distribution, geological succession of fossils, and such other facts, might come to the conclusion that each species had not been independently created, but had descended, like varieties, from other species. Nevertheless, such a conclusion, even if well founded, would be unsatisfactory, until it could be shown how "the innumerable species inhabiting this world have been modified, so as to acquire that perfection of structure and coadaptation which most justly excites our admiration. (Darwin, 1859, p. 66)

In considering the origin of phyla and the stability of the major body plans, it is quite conceivable that scientists, reflecting upon the empirical evidence of the history of life on earth might come to the conclusion that mechanisms exist which prevent major evolutionary change from occurring on a gradual step-by-step basis. Stasis is a dominant feature of the fossil record and mechanisms must exist which account for it. Ironically, natural selection itself may play a major role in the phenomenon of higher taxon-level stasis.

One of many evolutionists critical of Darwin, Soren Lovtrup points out that "some critics turned against Darwin's teachings for religious reasons, but they were a minority; most of his opponents "... argued on a completely scientific basis." He further explains:

...the reasons for rejecting Darwin's proposal were many, but first of all that many innovations cannot possibly come into existence through accumulation of many small steps, and even if they can, natural selection cannot accomplish it, because incipient and intermediate stages are not advantageous. [Lovtrup]

Perhaps the most formidable of Darwin's critics was St. George Mivart. His major book, On the Genesis of Species, took aim at the notion that natural selection could account for the accumulation of the incipient stages of useful. [Mivart] Stephen Jay Gould notes that

Darwin offered strong, if grudging, praise and took Mivart far more seriously than any other critic...Mivart gathered, and illustrated "with admirable art and force" (Darwin's words), all objections to the theory of natural selection—"a formidable array" (Darwin's words again). Yet one particular theme, urged with special attention by Mivart, stood out as the centerpiece of his criticism. It remains today the primary stumbling block among thoughtful and friendly scrutinizers of Darwinism. No other criticism seems so troubling, so obviously and evidently "right" (against a Darwinian claim that seems intuitively paradoxical and improbable).

Mivart awarded this criticism a separate chapter in his book, right after the introduction. He also gave it a name, remembered ever since. He called it "The Incompetency of 'Natural Selection' to account for the Incipient Stages of Useful Structures." If this phrase sounds like a mouthful, consider the easy translation: we can readily understand how complex and fully developed structures work and owe their maintenance and preservation to natural selection—a wing, an eye, the resemblance of a bittern to a branch or of an insect to a stick or dead leaf. But how do you get from nothing to such an elaborate something if evolution must proceed through a long sequence of intermediate stages, each favored by natural selection? You can't fly with 2% of a wing or gain much protection from an iota's similarity with a potentially concealing piece of vegetation. How, in other words, can natural selection explain these incipient stages of structures that can only be used (as we now observe them) in much more elaborated form? [Gould]

Gould then pointed out that among the difficulties of Darwinian theory "one point stands high above the rest: the dilemma of incipient stages. Mivart identified this problem as primary and it remains so today."

There are numerous examples of organisms with systems of highly specialized, interdependent components, all of which must be integrated before they are functional and offer any selective advantage. Nature abounds in such systems of "irreducible complexity." Although there may be some examples where certain components take on some preadaptive function, these cases may be considered as exceptions to a more general rule. As a rule, any subset of the components would prove to be a burden to an organism and thus be eliminated by natural selection. Take for example the sensory and motor mechanism of the common bacterium, Escherichia coli, a relatively simple unicellular prokaryotic organism.

The sensory and motor mechanism consists of a number of receptors which initially detect the concentrations of a variety of chemicals. Secondary components extract information from these sensors which in turn is used as input to a gradient sensing mechanism. The output of this mechanism is used to drive a set of constant torque proton-powered reversible rotary motors which transfer their energy through a microscopic drive train and propel helical flagella (figure not available). This highly integrated system allows the bacterium to move at the rate of approximately ten body lengths per second.

Dr. Robert Macnab of Yale University concluded a major 50 page review of this mechanism with these remarks:

As a final comment, one can only marvel at the intricacy in a simple bacterium, of the total motor and sensory system which has been the subject of this review and remark that our concept of evolution by selective advantage must surely be an oversimplification. What advantage could derive, for example, from a "preflagellum" (meaning a subset of its components), and yet what is the probability of "simultaneous" development of the organelle at a level where it becomes advantageous? [Macnab]

Each component in the flagellum alone (see figure below) is highly specialized in its function and it is highly unlikely that many of the components, if any at all, would have some preadaptive value. A subset of components would constitute a collection of superfluous parts which according to Darwinian theory should be eliminated by natural selection. Darwin pointed out in The Descent of Man [Darwin] that natural selection would act to preserve those individuals which were least encumbered with a superfluous part. Although this is one of the simplest organisms on our planet, it serves to illustrate how natural selection contributes to the phenomenon of stasis and helps explain the fact that most species do not arise gradually by the steady transformation of their ancestors.

On the Origin of Species by Means of Natural Selection is Charles Darwin's classic persuasive and compelling argument that minor evolutionary change could be extrapolated to account for the origin of the all of the major forms of life by purely mechanistic and materialistic processes. Writing on the origin and impact of evolutionary thought, Douglas Futuyma put it this way:

Darwin showed that material causes are a sufficient explanation not only for physical phenomena, as Descartes and Newton had shown, but also for biological phenomena with all their seeming evidence of design and purpose. By coupling undirected, purposeless variation to the blind, uncaring process of natural selection, Darwin made theological or spiritual explanations of the life processes superfluous. Together with Marx's materialistic theory of history and society and Freud's attribution of human behavior to influences over which we have little control, Darwin's theory of evolution was a crucial plank in the platform of mechanism and materialism—of much of science, in short—that has since been the stage of most Western thought. [Futuyma; our emphasis—eds.]

Were Darwin's extrapolations justified? Probably not, judging from the conclusions of many of the scientists attending one of the most important conferences in evolutionary biology in the past forty years.

The central question of the Chicago conference was whether the mechanisms underlying microevolution can be extrapolated to explain the phenomena of macroevolution. At the risk of doing violence to the positions of some of the people at the meeting, the answer can be given as a clear, No. [Lewin]

Reporting on the conference in Science, the prestigious journal published by the American Association for the Advancement of Science (AAAS), Lewin described some of the major conflicts between the modern neo-Darwinian theory of evolution and the empirical evidence:

Evolution, according to the Modern Synthesis, moves at a stately pace, with small changes accumulating over periods of many millions of years yielding a long heritage of steadily advancing lineages as revealed in the fossil record. However, the problem is that according to most paleontologists the principle feature of individual species within the fossil record is stasis, not change...

In a generous admission Francisco Ayala, a major figure in propounding the Modern Synthesis in the United States, said "We would not have predicted stasis from population genetics, but I am now convinced from what the paleontologists say that small changes do not accumulate." [Lewin]

If small changes do not accumulate, if stasis is the principle feature of individual species in the natural history of life, if natural selection inhibits or precludes major evolutionary change, if the order of appearance in the geologic record is systematically backwards to Darwinian predictions, and if the higher taxa are as discontinuous as they appear to be, why is it that scientists don't develop theories to explain the natural limits to biological change? The answer seems to be more philosophical than empirical. Although the question would probably lead to a more accurate description of nature, it would undoubtedly undermine the pervasive secular philosophy of mechanism and materialism which has come to dominate modern science. Although the question could certainly lead to fruitful scientific research, the thought that natural processes might actually prevent major evolutionary change from occurring would be anathema to those scientists who hold to some form of philosophical naturalism or secular religion.

In a recent AAAS conference Michael Ruse, philosopher of science and noted defender of Darwinism, admitted that evolutionary theory is based upon metaphysical assumptions.

And certainly, there's no doubt about it, that in the past, and I think also in the present, for many evolutionists, evolution has functioned as something with elements which are, let us say, akin to being a secular religion ... And it seems to me very clear that at some very basic level, evolution as a scientific theory makes a commitment to a kind of naturalism, namely, that at some level one is going to exclude miracles and these sorts of things come what may." [Ruse]

In other words, no matter what the evidence infers, no matter how inadequate Darwinian theory might be, only naturalistic explanations to questions of origins will be considered scientific.

If we assume science to be limited to the study of purely materialistic processes and we further assume that the origin of life and the origin of the major body plans are subject to scientific investigation, then the only truly scientific explanation of origins must be materialistic and naturalistic by definition. Under these rules of reasoning some form of Darwinism is the only possible "scientific" explanation of origins. Creation in any form, including theistic evolution, is by definition "unscientific."

Such reasoning is reflected in a booklet published by the National Academy of Sciences entitled Science and Creationism. The influential National Academy of Sciences, representing the nation's most notable scientists, has argued that the concept of creation is not scientific:

...it fails to display the most basic characteristic of science: reliance upon naturalistic explanations. Instead, proponents of "creation-science" hold that the creation of the universe, the earth, living things, and man was accomplished through supernatural means inaccessible to human understanding. [National Academy of Sciences]

The National Academy of Sciences simply defined away all alternatives to purely naturalistic evolution by insisting that only naturalistic explanations can be considered in answering questions of ultimate origins. By definition there is no scientific alternative to the idea that "man is the result of a purposeless and natural process that did not have him in mind." [Simpson]

Proponents of "creation-science" or advocates of "intelligent design" have never pretended to explain the mechanism by which the universe, the earth, living things, or man came into existence. For the most part, they have attempted to critique evolutionary theory and to point out areas of the theory which are either untestable or in conflict with empirical data. In so doing, they have inferred that purely mechanistic processes are insufficient to account for the order and complexity of the cosmos. This has provoked an almost religious reaction from the Academy:

"Creation-science" is thus manifestly a device designed to dilute the persuasiveness of the theory of evolution. The dualistic mode of analysis and the negative argumentation employed to accomplish this dilution is, moreover, antithetical to the scientific method.

Berkeley law professor, Phillip E. Johnson, in his recent book, Darwin On Trial, concludes:

The Academy thus defined "science" in such a way that advocates of supernatural creation may neither argue for their own position nor dispute the claims of the scientific establishment. That may be one way to win an argument, but it is not satisfying to anyone who thinks it possible that God really did have something to do with creating mankind, or that some of the claims that scientists make under the heading of "evolution" may be false. [Johnson]

Must scientists and science educators continue to operate under the supposition that origins must be accounted for by purely unguided naturalistic processes? Despite the fact that all other explanations of origins fail to meet the Academy's definition of science, the answer is a clear, "No!" It is clearly beyond the realm of science to make such a religious assumption. Science must remain agnostic on the matter. God may have created or God may not have created. If He created, then the cosmos may exhibit an evolutionary or developmental continuity. It may just as well exhibit natural discontinuities. If He did not create, then the cosmos must exhibit an evolutionary or developmental continuity.

What is so ironic is that a theistic worldview is open to a wider range of empirical and historical possibilities than an atheistic worldview is. If theism can accommodate a continuous cosmos but atheism cannot tolerate a discontinuous one, then why would any scientist begin with atheistic assumptions? It is obviously far better to assume that God did create and ask how to best model the creation than it is to assume that He played no role whatsoever in the history of life on Earth. At the very least, all scientists need to be honest agnostics. The bottom line is the same. Scientists need to be open to the empirical possibility that nature is fundamentally discontinuous.

Continued Part IV