Molecular Clock Keeps Wild Time

Evolutionists used to hope that the mutation rates in genes were relatively constant, so that they could provide a kind of “molecular clock” for inferring dates of divergence of ancestral species.  The first bad news was that not all molecular clocks tick at the same rate (rate heterogeneity).  Then they hoped that rate differences corresponded to body size, because there appeared to be such a trend among vertebrates.  The second bad news now comes out; according to an international team publishing in PNAS,¹ rate variation does not scale with body size:

The existence of a universal molecular clock has been called into question by observations that substitution rates vary widely between lineages.  However, increasing empirical evidence for the systematic effects of different life history traits on the rate of molecular evolution has raised hopes that rate variation may be predictable, potentially allowing the “correction” of the molecular clock.  One such example is the body size trend observed in vertebrates; smaller species tend to have faster rates of molecular evolution….
    Phylogenetic comparative methods were used to investigate a relationship between average body size and substitution rate at both interspecies and interfamily comparison levels.  We demonstrate significant rate variation in all phyla and most genes examined, implying a strict molecular clock cannot be assumed for the Metazoa.  Furthermore, we find no evidence of any influence of body size on invertebrate substitution rates.  We conclude that the vertebrate body size effect is a special case, which cannot be simply extrapolated to the rest of the animal kingdom.   (Emphasis added in all quotes.)

¹Thomas et al., “Evolution: There is no universal molecular clock for invertebrates, but rate variation does not scale with body size,” Proceedings of the National Academy of Sciences, published online before print May 1, 2006; Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0510251103.

Though disappointing to Darwinists, this will in no way affect their theories, because Darwinism does not rely on empirical evidence for support.  Evidence is just a nice thing to have when available.  Darwinism is more like entertainment; the show must go on.  Should non-Darwinists call this entertainment a comedy, or a tragedy?