Anecdotal , Historical and Critical Commentaries on Genetics Edited by James F . Crow and William F . Dove Thomas H . Jukes ( 1906 – 1999 )

TOM Jukes accepted our invitation to write a Perspecduced an immediate outcry from traditional students of evolution, undoubtedly abetted by the title. In the tives on the early history of molecular evolution, and in August 1999 he sent a rough beginning conensuing polemics, Kimura played the major role. King died prematurely in 1983 and Jukes wrote mainly about taining some now-forgotten early history. He planned an extensive revision and continuation, but on November 1 other things, although he did participate in one joint paper (Jukes and Kimura 1984). One of his interests his death intervened. We have decided to publish his early draft, realizing that it was but a start toward the was the evolution of the genetic code (Jukes 1983). I particularly liked his showing how, in an orderly sequenarticle that he had planned. Tom, along with Jack L. King and Motoo Kimura, tial way, mutation pressure in the codon and anti-codon could produce the unexpected codes in bacteria and formulated the neutral theory of molecular evolution. Earlier, the idea had been foreshadowed by Sueoka mitochondria (Jukes 1985). He also developed a widely used correction for multiple undetected changes in evo(1962) and Freese (1962). They had each suggested mutation pressure of near-neutral changes to account lutionary base substitutions (Jukes and Cantor 1969). Kimura became a crusading advocate for the neutral for the much greater diversity of DNA than of amino acid content among bacterial species. Remarkably, they theory and spent the rest of his life on the subject. In one paper after another, he offered further, increasingly had these insights before the redundancy of the code was recognized. convincing evidence. He also developed a solid mathematical theory, much of it carried over from his own The neutral theory of molecular evolution in eukaryotes started with Kimura (1968). He argued that the earlier work, which turned out to be remarkably well preadapted for use in molecular evolution. His book rate of protein evolution was too fast to be compatible with Haldane’s (1957) cost of natural selection, and The Neutral Theory of Molecular Evolution (Kimura 1983) became a landmark. The jury is still out as to the full therefore most of the changes must be neutral, driven extent of random changes in determining the course by mutation and random drift. King and Jukes (1969) of molecular evolution, but the neutral theory has had independently arrived at the same conclusion and formed a basis for phylogenetic reconstruction and the discovered Kimura’s paper while writing theirs. They molecular clock; it has also become the null hypothesis submitted a manuscript to Science, only to have it turned for numerous selection experiments. Kimura died in down. One reviewer said it was obviously true and there1994 (Crow 1995). fore trivial; the other said that it was obviously wrong. Happily, there was never a public rivalry among the King and Jukes appealed, and the second time it was three discoverers. King and Kimura were frequent accepted. This time I was a reviewer; if my recommendafriendly correspondents. Jukes (1991) acknowledged tion was decisive, I am pleased. The King and Jukes Kimura’s great contributions and sent him a reprint approach was quite different from Kimura’s and inwith “best wishes and thanks.” Kimura rightly receives cluded a number of arguments. It was more convincing, the lion’s share of the credit, but we should not forget partly because of their marshaling a larger variety of the independent discovery by King and Jukes and the evidence and partly because of growing doubt of the two forerunners, Sueoka and Freese. applicability of Haldane’s principle. Jukes was primarily a nutritionist, with a number of The King-Jukes paper had the intentionally provocasolid accomplishments, especially in vitamins. Some of tive title, “Non-Darwinian evolution.” The theory prothese have been mentioned by Maddox (1999). Jukes was also an outspoken polemicist and did not hesitate to speak clearly and forcefully against what he thought Author e-mail: [email protected]