A colleague suggested I post in several installments my past response to critics of Icons of Evolution. The series begins here, which includes the full reviewer citations.
(g) Wells is factually accurate
In my humble opinion, my critics have failed to show that my disbelief in Darwinian doctrine is due to ignorance of the facts. Indeed, reviewer Martin acknowledges that Icons of Evolution “is factually accurate.” He concludes: “If Wells made a technical error, I missed it.” (Martin, pp. 242, 246)
At the same time, I freely admit my ignorance about many things. I am ignorant of how life originated--but so is everybody else. I am ignorant of many details of the fossil record--but the abrupt appearance of major animal groups in the Cambrian explosion is not a detail, it is one of the fossil record’s most obvious features. I am ignorant of many aspects of vertebrate embryology, despite my Ph.D. in the field--but I do know that what Darwin called the “strongest single class of facts” in favor of his theory is not factual at all. I am ignorant about many things concerning peppered moths--but I know enough about the “investigative tradition” in science to recognize the phoniness of statistics “proving” that the moths rest where experts say they don’t. I am ignorant of many things in developmental genetics, despite my Ph.D. training--but I do know that four-winged fruit flies are hopeless monsters, not raw materials for evolution. Finally, I am ignorant of many aspects of human origins--but I know that fossils alone are not sufficient to demonstrate descent with modification.
So the problem is not my ignorance. Perhaps it’s my stupidity. Let’s see.
WELLS IS STUPID
Ignorance is a lack of knowledge, but stupidity is a lack of mental ability. A stupid person can’t think straight. According to some of my reviewers, I disbelieve in Darwinian evolution because I confuse “unexplained” with “unexplainable,” I illogically criticize evolution because of a few textbook mistakes, and I fail to grasp the proper relationship between scientific theories and the evidence.
(a) Confusing “unexplained” with “unexplainable”
One of the icons of evolution I discussed in my book is homology in vertebrate limbs. A bat has wings for flying, a porpoise has flippers for swimming, a horse has legs for running, and a human has hands for grasping, yet the bone structures in their forelimbs are remarkably similar. Pre-Darwinian biologists called these structural similarities “homologies” and attributed them to a common archetype, or design. Darwin attributed them to inheritance from a common ancestor.
How can we determine which is correct? As we saw in Berra’s Corvette analogy above, mere similarities are not evidence for ancestry and descent; they are equally compatible with design. The only way to show that the Darwinian explanation of homology is correct is to demonstrate a natural mechanism. Only by showing how one car model could change into another through unguided natural processes (such as rust and wind) could we show that they evolved in a Darwinian fashion, without the need for design.
In the case of living things, two natural mechanisms have been proposed to explain homology: developmental pathways (with homologous features originating from similar cells and processes in the embryo), and genes (with homologous features being programmed by similar DNA sequences). But neither one of these proposed mechanisms fits the evidence: As a general rule, homologous features are not correlated with either similar developmental pathways or similar genes. Therefore, the Darwinian explanation (common ancestry) remains uncorroborated, and the classical alternative (common design) remains a viable option.
Reviewer Raff begins his criticism of my treatment of homology by quoting an essay I wrote with Paul Nelson in 1997: “Homology… cannot be attributed to similar developmental pathways any more than it can be attributed to similar genes. So far, the naturalistic mechanisms proposed to explain homology do not fit the evidence.” Raff continues: “What logical gymnastics! If it’s unexplained, it must be unexplainable by evolutionary biology. If it’s unexplainable by evolutionary biology, it must require an intelligent designer.” (Raff, p. 373)
The logical gymnastics, however, are Raff’s--not mine. My argument is that the “common ancestry” explanation for homology has not been empirically demonstrated, so the “common design” explanation cannot be ruled out. Is homology “unexplained” by evolutionary biology? Yes. Is it “unexplainable”? I don’t know. If homology is unexplainable by evolutionary biology, does it require an intelligent designer? Perhaps, if those are the only two possibilities. But I did not argue this in Icons of Evolution. I merely asserted that because Darwinism has not explained homology, it cannot exclude alternative explanations such as intelligent design.
Most biology textbooks, however, give the impression that the issue has been settled. They do this, not by providing evidence, but by defining homology as similarity due to common ancestry. Yet the same textbooks also claim that homology is some of the best evidence for common ancestry. In effect, they claim that similarity due to common ancestry is due to common ancestry. [21]
Is that what evolutionary biologists mean by thinking straight?
NOTES:
[21] Many biology textbooks define homology as similarity due to common ancestry, yet claim that it is evidence for common ancestry. For example, Starr and Taggart’s Biology: The Unity and Diversity of Life (8th Edition, 1998) states that the “pattern of macroevolution--that is, change from the form of a common ancestor--is called morphological divergence…. Homology [is] a similarity in one or more body parts in different organisms that share a common ancestor…. Homologous structures provide very strong evidence of morphological divergence.” (pp. 318-319) In a section on “The Evidence for Evolution” in the teacher’s edition of Johnson’s Biology: Visualizing Life (1998), students are told that “homologous structures are structures that share a common ancestor,” and an accompanying note tells the teacher that “such structures point to a common ancestry.” (p. 178) According to Campbell, Reece and Mitchell’s Biology (5th Edition, 1999), “similarity in characteristics resulting from common ancestry is known as homology, and such anatomical signs of evolution are called homologous structures. Comparative anatomy is consistent with all other evidence in testifying [to] evolution.” (p. 424) Raven and Johnson’s Biology (5th Edition, 1999), in a section titled “The evidence for macroevolution is extensive,” includes the following: “Homology: Many organisms exhibit organs that are similar in structure to those in a recent common ancestor. This is evidence of evolutionary relatedness.” A few pages later, the same textbook explicitly defines homologous structures as “structures with different appearances and functions that all derived from the same body part in a common ancestor.” (pp. 412, 416) Audesirk, Audesirk and Byers’s Life On Earth (2nd Edition, 2000) calls homology “evidence of relatedness” in a section titled “Comparative Anatomy Provides Structural Evidence of Evolution.” The textbook tells students: “Internally similar structures are called homologous structures, meaning that they have the same evolutionary origin despite possible differences in function. Studies of comparative anatomy have long been used to determine the relationships among organisms, on the grounds that the more similar the internal structures of two species, the more closely related the species must be, that is, the more recently they must have diverged from a common ancestor.” (p. 236)
