Darwinian evolution is widely advertised to be a fact, as firmly established as the shape of the Earth. Defenders of the theory insist that there is no scientific controversy over it, and people who question or criticize it are typically accused of being ignorant or religiously motivated. Yet every few years a book comes alongÃ¢â‚¬â€written by scientistsÃ¢â‚¬â€claiming to remedy some major flaw in evolutionary theory.
The Plausibility of Life, by Marc W. Kirschner and John C. Gerhart, is such a book. Gerhart is an eminent cell and developmental biologist, now retired after a distinguished career at the University of California at Berkeley; KirschnerÃ¢â‚¬â€once Gerhart’s graduate student (as was I)Ã¢â‚¬â€is an equally eminent biologist, now a department chair at Harvard University. According to the book’s jacket, the authors close “a major gap in Darwin’s theory” and thereby provide “a timely scientific rebuttal to critics of evolution who champion ‘intelligent design.'”
By acknowledging that Behe “sees the constraint in particular designs,” Kirschner and Gerhart implicitly concede Behe’s main point, which concerns only the irreducible complexity of the conserved core processes. Behe’s argument is untouched by the fact that the basic components may be wired together in a variety of ways. Yet Kirschner and Gerhart do not even attempt to explain the complexity in those components; they merely assert that intelligent design was unnecessary. “The great innovations of core processes were not magical moments of creation,” they write, “but periods of extensive modification of both protein structure and function.” Like Topsy in Uncle Tom’s Cabin, the core processes just grow’d.
Kirschner and Gerhart also criticize Phillip Johnson and me (without mentioning us by name, except in the notes). Darwin thought that “the embryos of the most distinct species belonging to the same class are closely similar, but become, when fully developed, widely dissimilar,” and that this provided “by far the strongest” evidence for his theory that all vertebrates are descended from a common ancestor. In the revised 1993 edition of Darwin On Trial, however, Johnson pointed out that Darwin was mistaken: Vertebrate embryos actually start out very dissimilar, then they become similar midway through development before diverging again. Darwinists typically dismiss this inconvenient discrepancy by arguing that early development can evolve easily. In other words, they simply assume the truth of their theory, then use it to explain why early vertebrate embryos are so different. What had been the strongest evidence for the theory turns out to be false, but the theory is taken to be true anyway and the anomalous evidence is explained away. According to Kirschner and Gerhart, this somehow transforms dissimilarities in early vertebrate embryos “from a confounding paradox of evolution to one of its strongest arguments.”
In my book Icons of Evolution, I pointed out that using structural similarity (“homology”) as evidence for Darwinian evolution is problematic. Without an unguided natural mechanism, it is impossible to establish that similarities are due to common ancestry rather than common design. Kirschner and Gerhart argue that their theory solves the problem. Maybe. Maybe not. It would help if they could provide good evidence for their theory, but the best they can do is promise us that such evidence will be forthcoming. In the meantime, they expect us to believe that “the modern molecular evidence for homology, its development, and its evolution, is unassailable.”
So what are we to make of The Plausibility of Life? Its authors claim to complete Darwin’s theory by closing its last remaining major gap, yet they concede that the completed theory has no explanation for the origin of core processes in the first cells, the first eukaryotes, the first multicellular organisms, animal body plans, or vertebrate limbs, heads and brains. There seem to be more gaps in evolutionary theory now than there were before Kirschner and Gerhart got started.
Perhaps it would be fairer to overlook the authors’ inflated rhetoric and judge them merely on the basis of their limited theory of facilitated variation. Even if we grant the existence of conserved core processes, have Kirschner and Gerhart succeeded in explaining how land vertebrates diversified into lizards, birds, mice, whales, bats, and humans? Although they assure us that evidence will be forthcoming, the mechanisms they proposeÃ¢â‚¬â€exploratory behavior, weak linkages, and compartmentalizationÃ¢â‚¬â€have never been observed to produce anything like the novelties needed by evolution. If a century of embryology has taught us anything, it is that we can fiddle with these mechanisms all we want in a mouse embryo, and there are only three possible outcomes: a normal mouse, a deformed mouse, or a dead mouse.
Despite the dubious nature of their theoretical proposal, Kirschner and Gerhart imply that anyone who continues to be skeptical of Darwinian evolution is close-minded. In particular, people who think that intelligent design might provide a better explanation for some features of living things are dismissed as ignorant, religiously motivated, and covertly seeking ways to evade the law. Like many of their fellow Darwinists, Kirschner and Gerhart ultimately resort to personal insults.
Does the theory of facilitated variation make life plausible? Not at all, since it assumes the existence of life in the first place. Does the theory of facilitated variation rebut intelligent design? Not at all, since it assumes the existence of irreducibly complex core processes in the first place. The principal take-home lesson from The Plausibility of Life is that evolutionary theory still suffers from major weaknesses, but anyone who says so without reaffirming Darwinism and condemning id is a close-minded, ignorant, Bible-thumping subverter of the Constitution.
Where’s the novelty in that?
There is something interesting in the fact that this article appears in Christianity Today. Biology and origins science are becoming hot topics of study in Christian circles. The other curious item is the number of ID proponents who find themselves publicly on the opposite sides of the ID debate with former teachers: Wells and Gerhart, Nelson and Wimsatt, Wise and Gould, Dembski and Shallit, etc.
(HT: Rob Crowther of evolutionnews.org for alerting me to the article)