Genetics of the Evolutionary Process
by Theodosius Dobzhansky
Columbia, 505 pp., $10.95
The Evolution of Man and Society
by C.D. Darlington
Simon & Schuster, 752 pp., $12.95
Scientists usually make their opinions and their findings known to each other through “papers”—contributions to learned societies or learned journals—by papers, that is to say, rather than by books. Every now and again there is a notable exception. One was Dobzhansky’s Genetics and the Origin of Species; a second was E. Mayr’s Systematics and the Origin of Species; a third, Simpson’s Tempo and Mode in Evolution. All three were published by the Columbia University Press: surely among the really notable publishing achievements of the twentieth century. The appearance of a new book by Dobzhansky prompted me to browse again in an older edition (1941) to see if I could recapture the excitement of reading a work which did more than any other to mark the distinction between the older evolution theory and the new.
The new evolution theory wedded Darwinism to Mendelian genetics. Many things changed. It was no longer believed that the evolution of organisms in the past was the work of a heroic macro-evolution quite different in kind from the petty and humdrum micro-evolution which can be shown to be at work today. No longer was it believed that the end product of an episode of evolution was the devising of some one genetic formula or “genotype” which represented the one highest possible degree of adaptedness of an organism to its environment. Instead of being regarded as a noisy epiphenomenon of an otherwise orderly and systematic process of evolution, inborn genetic diversity was shown to be universal in occurrence and significance, and indeed to be enforced by the action of natural selection.
Another idea which was superseded by the newer evolution theory was one I like to call the “dynastic” concept of evolution, which represents the evolutionary process by family trees much like those that illustrate the pedigrees of European royal families.
Unfortunately, alongside the newer evolution theory there grew up a conventional travesty that was described with contempt as “neo-Darwinism” by nature-philosophers who were not wise enough to keep their mouths shut. According to this travesty, what was, or was not, selected in the process of evolution was a mutant organism. When the environment of a population of organisms changes then the population has to change too. Fortunately, from time to time mutant organisms would appear which, so to speak, proffered their candidature for evolution. If they were the product of favorable mutations they were incorporated into the establishment, that is to say, they became part of what was still thought of as the genotype of the species. If not, they perished in the struggle for survival and were heard of no more.
What particularly enrages people who think that this travesty of evolution theory is what geneticists actually believe in is that mutation is avowedly a random process, so it would appear that the entire magnificent pageant of evolution culminating in no less an organism than H. sapiens was brought about by—chance!—a view which can be sustained only if …