Monday, March 06, 2006
Misstatements in Dr. Dan Ely’s Testimony About Evolution
This morning, RSR published a letter from Dr. Stephen C. Weeks, an evolutionary ecologist, Dr. Peter Niewiarowski, evolutionary ecologist, and Dr. Lisa Park, a paleontologist, to the Kansas Board of Education. (scroll down to read the letter) All three of the writers are colleagues of intelligent design activist Dan Ely at the University of Akron. Their letter calls attention to the "profound misconceptions" in Ely's testimony before the Topeka science hearings last May. Included with that letter is an addendum rebuting misstatements about evolution in Ely's testimony here. Here it is:
1. Within the sub-discipline of phylogenetic reconstruction, there are often disagreements between what morphologists have assumed the ancestral tree to look like and what molecular phylogeneticists have inferred from the DNA. Such disagreements are bound to happen; in fact they are a design feature of the process of science.
Phylogenetic reconstruction produces hypotheses to be tested by data (morphology, genetics, behavior, etc.), disagreement, testing, refining is the process that leads to robust views of ancestral relationships. Disagreements about the details of evolution by natural selection are a far cry from the types of major discrepancies in evolutionary biology that Dr. Ely and the other creationists are implying.
2. When Dr. Ely states “I can reclassify an animal into something else based on some other data,” he is not referring to reclassifying a mouse into an elephant or a primate into a bird, he is talking about “reclassifying” closely-related, very recently derived species. Classifications at such a fine scale are sometimes difficult, especially using DNA markers, since different sections of DNA are more or less prone to changes, and those DNA sections that change more slowly give different results than those that change quickly.
These “discrepancies” are once again minor details in the much larger field of evolutionary biology, and are more a reflection of our inability to detect relatively recent events using DNA evidence than a sign of any “major problem” with the theory of evolution.
3. Dr. Ely’s lack of understanding of evolution is apparent in his discussion of sequence divergence among major lineages in cytochrome-C. Dr. Ely makes the claim that organisms diverse as “horse, pigeons, tuna, silk moth, wheat and yeast” should “show a much greater divergence than about 64 percent” of their sequences for this molecule.
Dr. Ely seems to be revealing an underlying preconception that organisms as far apart as wheat and tuna MUST have DNA sequences that are not at all related. However, we have long known that certain aspects of our genome is highly conserved (i.e., hasn’t changed for hundreds of millions of years), and thus that widely divergent organisms have very similar genetic codes for these molecules.
Evolutionary biologists’ interpretation of this fact is that molecules like cytochrome-C are “constrained” in that DNA coding for these molecules cannot change much without the molecule becoming functionless. Other molecules (such as hemoglobin or fibrinopeptides) are less constrained, and thus differences between the same distantly related species that Dr. Ely refers to for these molecules would be much greater than 64 percent.
We teach this distinction in our basic evolution course, and if Dr. Ely was truly involved with evolutionary research, he would fully understand why his statement was either deliberately misleading or just a factual error on his part. Actually, we are embarrassed that Dr. Ely, in using this example, reveals such profound misconceptions about evolutionary biology.
4. Dr. Ely continues to show his ignorance of evolution in his discussion of evolutionary interpretation of his own research on the Y-chromosome. When Dr. Ely discusses the differences in amino acid sequence for the SRY region on rats, mice, and humans, he makes the claim that rats and mice “should be equally distant from human and they aren't.”
Dr. Ely describes differences between mice and humans of “four out of the six amino acids in the gene we're looking at as different” whereas between rats and humans there is “only one of six amino acids different.” This is a tiny sample size (six amino acids) and is most likely nowhere near a randomly drawn comparison.
When evolutionary biologists make claims about the relative similarity/differences among species, they compare thousands of amino acids, not six. Anyone could go through these thousands of comparisons and “cherry pick” a few that seems to show relationships that are counter-intuitive.
However, such a selective comparison is once again either deliberately misleading or a product of a lack of understanding of the processes evolutionary biologists use every day.Dr. Ely’s lack of understanding of the evolution of the Y-chromosome is evident by his misunderstanding of the processes causing its degeneration and the end result of the possibility that it may eventually be lost.
The Y-chromosome degenerates because it cannot be repaired by normal repair mechanisms available to chromosomes that can pair with “homologs” during meiosis. This inability to repair various forms of damage causes slow degeneration over thousands of generations, and has been well described using various evolutionary experiments.
In some lineages, the Y has degenerated so far as to be entirely lost, such that females are XX and males are XO (O meaning a loss of the Y chromosome). Dr. Ely suggests that the Y’s degeneration is “de-evolution,” and that humans will eventually lose the Y chromosome and then “schools out” (he later goes on to state that “we're going to lose the Y chromosome, therefore males”).
The long-term degeneration of the Y-chromosome is a result of various mutations, but does not imply that species are “de-evolving.” In fact, in some species of snakes, the more advanced species have the most degenerated Y-chromosomes! Furthermore, the statement that we are eventually going to lose our Y-chromosome, and thus males, is utter nonsense. Within any species, there is no inexorable march toward losing the Y-chromosome (many species have had degenerate Y-chromosomes for millions of years), and in those that have lost the Y-chromosome, maleness is determined via another mechanism and a loss of males does NOT happen (e.g., many snakes, fruit flies, nematode worms, etc.).
It is clear from these statements about his own research that Dr. Ely knows literally nothing about the evolutionary processes that he claims to be competent enough to criticize, which is understandable in that he is a physiologist with no graduate-level training in evolutionary biology whatsoever.
