|"Rev Dr" Lenny Flank
Joined: Feb. 2005
In the Anatomical Homology section, we have:
"Many biologists before Darwin thought that these similarities (called "homologies") were due to a common plan or "archetype".
This one doesn't seem to be specifically covered in the Index to Creationist Claims, but the whole "common plan" or "common design" argument is a long-lived creationist argument:
| "This idea that a fundamental similarity in structures is due to common descent is called homology. But this still-common idea is not in the slightest a proof of evolution. It is simply an assumption by those who reject creation.|
Darwin revealed this was his position when he said some believe ‘that it has pleased the Creator to construct all the animals and plants in each great class on a uniform plan’. He finished that sentence by saying, ‘but this is not a scientific explanation.’3 He was therefore ruling out the possibility of creation based on a common plan by implying it was not scientific, so he wouldn’t believe it whether it was true or not."
"So-called homologous structures are no proof of common descent, so are no proof of evolution. Darwin’s approach—to reject the creation explanation as unscientific because you don’t want to believe it—is not rational. This is particularly so when the facts are readily explained as the product of a Designer who created each unique structure to fulfill a different purpose."
Answers in Genesis, Creation Magazine, "Similarities Don't Prove Evolution", March 1992
| My argument is that the “common ancestry” explanation for homology has not been empirically demonstrated, so the “common design” explanation cannot be ruled out. |
(Jonathan Wells, "Icons of Evolution -- A Response to Critics Pt 7"
| "The existence of similarities between organisms--whether in external morphology or internal biochemistry--is easily explained as the Creator's design of similar systems for similar functions, but such similarities are not explicable by common evolutionary descent."|
Henry Morris, "The Vanishing Case for Evolution", ICR Impact, June 1, 1986)
"Some modern biologists explain homology in another way. Brian Goodwin of the Open university says homology does not reflect a process of historical change, but instead reflects contraints imposed upon the structure of organisms by the laws of nature. Goodwin contends that the laws of nature dictate that a liquid, for example, has only a limited number of shapes it can take -- a spiralling funnel when going down the drain, a droplet when it falls, and so on. In the same way, says Goodwin, the laws of nature ensure that only a certain number of anatomical patterns are possible. Therefore, we should expect to see similarities in the anatomical structure of even different types of organisms."
This isn't addressed in the Index of Creationist Claims. I cite it here just to point out that Nelson and his ilk are either too stupid or too dishonest to differentiate between "homology" and "analogy".
"Contrary to these predictions, biologists are learning that homologous structures can be produced by different genes and may follow different developmental pathways."
CB811 "Homologous structures are not produced by homologous genes"
"In another surprising twist, biologists have also discovered many cases in which the same genes help to produce different adult structures. Consider, for instance, the eyes of the squid, the fruit fly and the mouse (see figure 2:2). The fruit fly has a compound eye, with dozens of separate lenses. The squid and the mouse both have single-lens camera eyes, but they develop along very different pathways, and are wired differently from each other. Yet the same gene is involved in the development of all three of these eyes."
This one isn't addressed in the Creationist Claims Index either, though it is a subspecies of CB811. Nelson and his ilk, of course, are simply being dishonest by not mentioning that the common gene involved is a HOX gene, which doesn't regulate the detailed structure of the eye.
"Some scientists are skeptical that an undirected process like natural selection and mutation would have stumbled upon the same complex structure many different times."
This isn't specifically covered in the Index to Creationist Claims -- it's sort of a conflation of CB100 "mutations are rare", and CB 150 "Functional genetic sequences are too rare to evolve from one to another". I cite this sentence primarily to contrast it with the earlier sentence: " In the same way, says Goodwin, the laws of nature ensure that only a certain number of anatomical patterns are possible. Therefore, we should expect to see similarities in the anatomical structure of even different types of organisms." On page 43, we are told that body structures are tightly restricted by natural law to just a few possible SIMILAR STRUCTURES. Then, just five pages later, we are told that evolution faces a problem because mutations KEEP PRODUCING SIMILAR STRUCTURES. (sigh)
"This made the concept of homology circular, say many critics. If homology is defined as 'similarity due to common ancestry', then to say that homology provides evidence for common descent is to reason in a circle."
CB810 "Homology cannot be evidence of ancestry if it is defined thus."
Editor, Red and Black Publishers