 The interaction of selection and random drift across linked regions of DNA sequence is one of the most active current areas of theoretical and empirical research in molecular evolution. Theory shows that it can be difficult to separate cleanly the action of the evolutionary forces of selection and drift except for certain regions of parameter space, whose generality remains unknown and subject to much debate. Like the study by Fisher and Ford (1947), most empirical studies interpret all deviations away from strictly the neutral expectation as evidence of natural selection without addressing the issue of agency. For example, codon bias is evidence that natural selection affects even the apparently non-functional components of genes. Thus, the original ecological genetic view that natural selection is the only significant evolutionary force characterizes much of modern molecular evolution, despite progress in theory and the availability of much more reductionistic genetic methods. The parallels between the summary statement of Ford  (1975: 389; see above)  and that of the molecular evolutionary geneticist, E. Nevo, twenty-five years later are remarkable: 