Momma's Boy

Using our favorite examples of the bat and whale, consider what happened according to the Darwinian scheme following the original split from the putative common ancestor of mammals, the reptiles. A sequence of conserved changes eventuated in the animals we know today. The experiences of the two evolutionary sequences would have become more and more disparate as the divergence progressed. Yet when the molecular evidence is consulted--the types of enzyme cytochrome c found in homologous structures, for example--changes have occurred at roughly the same rate and they are chemically equidistant from comparison molecules in any modern reptile. But if these molecular mutations have been occurring regularly without regard to environmental pressures (in contrast to the prevailing view of natural selection), what is the implication for Darwinism? This "molecular clock" concept forms the central idea in a theory known as the neutral theory of molecular evolution. The "neutral" part refers to molecular changes that have no impact upon functionality, such as the variations in cytochrome c. It is a neat way to account for the heterogeneity found in organisms, greater than would be expected by selection and it acutally improves the explanatory power of Darwinism. A specific example of how the idea of the molecular clock has been put to use is the recent theory that all humans now living are the descendants from one woman who lived in Africa less than 200 million years ago--the so-called "mitochondrial Eve," because the studies that led to this conclusion were done on mitochondrial DNA, which is conserved as it is passed through the maternal line [mitochondria are self-replicating organelles within eukaryotic cells that are present in the ovum but lacking in the head of the sperm that fertilizes--hence all the mitochondria in my body came from my mother, and all the mitochondrial DNA is passed through the generations through the maternal line]. This has caused some controversy between the molecular anthropologists and the fossil-based anthropologists, as their sequences of descent don't agree.

All of this would seem quite impressive, and it certainly can be daunting to the inexperienced, but at basis it simply distracts attention from the fact that the molecular clock hypothesis assumes the truth of the common ancestry thesis that it is supposed to confirm. It is a technically sophisticated restatement of the argument from classification and relationships.

So we are back to our tautologies. Evolution is true by definition. But the molecular evidence to which scientists appeal has not provided the necessary transitional forms to create links to purported common ancestors and there remains no corroboration that natural selection actually has the power to conserve and aggregate the types of changes required to explain the complexity and diversity of life on earth. Indeed, the molecular evidence has only added to the burden of unexplained complexity.