Molecular Evolution Activities



Online Document

Jack King and Thomas Jukes, "Non-Darwinian Evolution," Science 164 (1969), 788-798.
[Summary] [PDF 3MB]

King and Jukes begin with a polemically-worded introduction, in which they proclaim that recent developments in molecular biology have made it both possible and necessary to reexamine many of the assumptions of Darwinism. Contrary to what "classical evolutionary biologists" like G.G. Simpson believe, they suggest that evolution at the molecular level may be governed by a mechanism completely different from natural selection. Indeed, they argue that most mutations that become fixed in the genome must be selectively neutral, since Darwinian evolution at the rate of one amino acid substitution every 2 years (or even every 50 years) would be more costly than any species could afford. While they agree with Kimura (1968) on this point, they find fault with his methodology on many points, including: his failure to take into account the lethality of most mutations and his assumption that most mammalian DNA consists of structural genes. Indeed, King and Jukes argue that only about 5-10% of nucleotide substitutions are neutral, occurring primarily in regions that are not involved in protein function. King and Jukes support their conclusion with a litany of data from comparisons of protein and DNA sequences in a wide variety of species.


This page was written by Michael Dietrich and Jay Aronson. It was last updated on May 15, 2004.