The twentieth century's revolution in molecular biology has produced volumes of sequence data which evolutionists have marshaled in defense of their theory. One high-profile example is the molecular similarity between humans and chimpanzees. First proteins and later the genomes of these two species were found to be practically identical. These findings have often been touted as compelling confirmations of evolution. But there are also differences—significant differences. One example is the differences in the Y chromosome, which recent research has elucidated. These differences are explained by evolutionists, of course, as arising from various evolutionary processes. But the differences are significant and the evolutionary scenarios are speculative. In fact a recent paper appealed to several different mechanisms in order to explain the differences. Of course none of this is impossible, but the ease with which evolutionists can explain observations that are at various points in the spectrum (such as high similarity and significant difference) is an example of why some observers view evolution as a tautology. When I pointed this out evolutionists responded with a variety of protectionist maneuvers. Here is an example.
Background
You may recall from your biology class that most mammal species have two sex-determining chromosomes labeled X and Y. A pair of X chromosomes makes for a female whereas an X and Y pair makes for a male. Unlike the other chromosome pairs in which the two chromosomes are highly similar, the X and Y chromosomes are quite different. The most obvious difference is in their sizes—the Y chromosome is quite a bit smaller than the X chromosome. And not surprisingly the Y chromosome contains genes that are male-specific.
Focusing on the Y chromosome, it is comprised of half-a-dozen different types of regions, distinguished both by differences in structure as well as content. For instance, the ampliconic regions contain long, repeated sections, often arranged in molecular palindromes. The X-transposed regions contain genes that are highly similar to counterparts in the X chromosome, and the X-degenerate regions contain gene remnants.
New findings
Recently the chimpanzee Y chromosome was decoded and compared to its human counterpart. Unlike previous DNA comparisons between the two species that revealed high similarity, the two Y chromosomes show substantial differences. The cousin genes present in both chromosomes are highly similar, but about a third of the genes have no cousin in the other chromosome. Also there are no X-transposed regions in the chimp Y chromosome, and overall the chimp has significantly fewer genes. On the other hand, the chimp’s ampliconic regions contain about twice as many long palindromes as the respective human regions. As the paper explained, these chimp and human regions “differ radically in sequence structure and gene content.” The illustration below shows these differences in the chimp and human Y chromosomes.
A tautology?
Prior to these findings evolutionists had thought the pattern of diminished size of Y chromosomes was due to a decaying action that slowed over time. These new findings don’t fit that hypothesis as there is far too much difference between the human and chimp Y chromosomes. Consequently they need another explanation. In fact multiple explanations are required to explain the many differences. So evolutionists say these differences are a consequence of “rapid divergence” driven by various “synergistic factors.” There was, for example, the “brisk kinetics” of ectopic recombination, genetic hitchhiking, and the great competition for mates amongst chimpanzees.
Impossible? Not at all. Indeed, it certainly is true that the Y chromosome is a unique type of chromosome. But the ease with which evolutionists can swap in opposing hypotheses and explain findings from across the spectrum, feeds the view the evolution is a tautology. Whatever is found, some say, evolution has an explanation for it.
Criticism
When I pointed this out one evolutionist responded with harsh criticism. But he seemed more intent on protecting the theory of evolution rather than exploring possible implications of the new findings. His response was notable because he is well known for his intelligence and communication skills. This was not the diatribe of some unknown critic. And that is why his comments are important. Unfortunately, theory protectionism is too often the first response of evolutionists.
He wrote that my article was shameless, shocking and incompetent. He went on to write that “His views on this topic are about the equivalent of some college freshman who wrote an essay on a biological topic without doing the responsible thing and doing the basic background research first. In a student, it would excusable, kind of, but for a Ph.D. presenting himself as an expert, holding forth on a blog, and posting his stuff on other blogs, and generally on a mission to "inform" the public about evolution, it's incredible.”
But what was shameless, shocking or incompetent about pointing out the reaction of evolutionists to these new findings, and the context of their previous claims? In fact, his specific complaints did not back up his criticism.
For instance, he wrote that “there are a lot of standard, well-known population genetics reasons why things like the Y-chromosome should evolve rapidly.” But if it were so obvious then evolutionists would not have been surprised by the new findings. They would not have to replace their decay hypothesis with new mechanisms. Certainly evolution would not have been harmed if substantially greater similarity had been found.
He also wrote that “the subjective ‘amount’ of change is not the most important thing, especially because things like deletions can cause ‘a lot’ of ‘difference’ in sequence, but actually reflect a very few events. Others have already pointed out that the non-deleted sequence maintains quite high similarity.”
True, a single deletion can cause substantial change, but for now we do not even know what degree of the observed differences can be explained by deletions.
He next wrote “the amount of change also isn't the most important thing because common ancestry doesn't predict that everything will evolve at exactly the same rate (which is what Hunter, stunningly and ridiculously, implies), rather it predicts that, whatever the rate of sequence change, humans and chimps will usually be closest to each other, gorillas will be a little farther (but not much), then orangs, then gibbons, then old-word monkeys, then new world monkeys, then lemurs, then other placentals, then marsupials, etc.”
But I implied no such thing. The evolutionist finds my article to be shameless, shocking and incompetent, yet he works from a misreading of it. He next wrote that “There is a massive amount of literature just on the evolution of sex chromosomes, it's a classic example of a highly successful application of population genetics and evolutionary biology, and Hunter is embarrassing and discrediting himself and creationists in general by irresponsibly blathering about a topic like this when he clearly knows jack squat about it.”
While it is true that there is substantial evolutionary literature on the evolution of sex chromosomes, this body of work is based on the presupposition that evolution is true. That is understandable for practical reasons, but it means that heroic assumptions go unquestioned. This body of work is very much a part of evolutionary thought—it is not work done from a theory-neutral perspective.
Finally, he criticizes my article for not presenting its own prediction. Here the protectionism becomes obvious. The evolutionist's heated criticism has long since left the actual article. The article is said to be shameless, but yet it is nowhere to be seen in the criticism.
If this were science, evolutionists would acknowledge that their theory is not a fact as much as is gravity. But instead they make this claim, and they use protectionist moves to avoid criticism.
