In a just published article in Plos Genetics, Merdith, et. al., study the enamilin gene (ENAM) in four different orders of placental mammals having both toothless and/or enamelless taxa. Their results show that, indeed, the enamelin gene is basically in place in the toothless taxa, but that either “frameshift mutations and/or stop codons” are found in the toothless and enamelless taxa. They then use a “novel method based on selection intensity estimates” to determine whether molecular evolutionary history of ENAM would ‘predict’ the occurence of enamel in “basal representative of Xenartha (sloths, anteaters, armadillos)”, which contains many frameshift mutations.
Our results link evolutionary change at the molecular level to morphological change in the fossil record and also provide evidence for the enormous predictive power of Charles Darwin’s theory of descent with modification.
Enormous predictive power? Really? It seems to me that if there is any “power” to Darwin’s theory, then it must come from its ability to demonstrate how new structures arise, not how previously occurring structures disappeared.
Furthermore, from the writings of Fred Hoyle, and the recent work of Behe (The Edge of Evolution), what we, here at UD would predict, is that the ‘loss’ of teeth or enamel wouldn’t involve more than two amino acid substitutions. This is, more or less, what Meredith, et. al. found. So, whose predictive power is enormous and whose not? Darwin wasn’t the first to suggest descent with modifcation. He was the first, however, to claim that nature alone, with variation combined with selective pressures and strong laws of inheritance, could account for the diversity we see and the seeming incredible complexity of such organs as the eye. This was his prediction, then, not that the loss of a function could be traced back in time–the fossil record tells us as much (Dollo’s Law was formulated in the 19th Century; see below). OTOH, using real numbers with equations that realistically represent life, UDers would predict that the operative gene-transcribed protein would be off by only two amino acids. To me this is the more impressive prediction.
Now, Meredith, et. al. do find there are the equivalent of three amino acids that are substituted for in some taxa. However, we’re dealing with such ancient lines, going back millions of years in the fossil record, that something called Gallo’s Law can, and should be invoked. Dollo’s Law says that features/structures in fossil species, once disappearing, never appear in the the fossil record again. They’re simply lost. Hoyle, in his book, “The Mathematics of Evolution”, based on realistic numbers applied to the equations he develops, concludes—predicts, if you will— that if a species moves away from its current genotype by more than two amino acids in any particular gene, then the loss of gene function will never again be recovered. That some orders of mammals are off by three amino acids simply tells us that this function was lost sometime in the very distant past, and that it has never reappeared again in the fossil record. This is what Hoyle would have predicted by simply looking at the molecular data. And, of course, the fossil record bears this out.