organisms sixty-five to seventy million years ago to a catastrophic encounter between the earth and an asteroid perhaps five or six miles in extent.

Gould holds for an evolutionary theory of “punctuated equilibria” in opposition to “gradualism.” Evolution does not require gradual change as Darwin had supposed. The absence of transitional forms in the fossil record which would bear out gradualism is described by Gould as the “trade secret of paleontology.” Such transitional forms (missing links) are rare, Gould believes, because evolutionary change was so rapid that the chance of such forms being preserved as fossils is statistically very low. As he reads the fossil record (and this is the paleontologist’s job), Gould finds that most species exhibit no change over their lifetimes in geological time and that new species appear very quickly from the standpoint, once again, of geological time. So evolution takes place not simply in the gradual change of one species into another but rather in two ways: the first, termed “phyletic,” involves the change of an entire population of organisms from one state to another; the second, termed “speciation,” sees the branching off of a species from a main stock. For Gould, speciation is rapid splitting in small populations which for geographical, behavioral, or other causes are isolated from the parent stock. (For behavioral reasons a small group may still be geographically associated with the parent stock but no longer breeds with it. A recent report in Science, in July, 1981, suggests precisely such a phenomenon involving hamsters.) Thus, the means by which speciation takes place involve not the gradual accumulation of minute variations but rather some sort of macromutation (large mutation).

The geneticist Richard Goldschmidt had urged such a hypothesis from the 1940’s onward. Gould believes that Goldschmidt was wrong about details and mechanisms but right in concept. As people learn more and more about the processes of individual development (ontogeny), they understand that small changes arising from mutation could produce small changes in early developmental stages. These small changes can translate into large differences in adults, hence, a possible means of accounting for rapid origins. Gould, in the very best scientific spirit, admits that this is his opinion. He does feel that his hypothesis evades the earlier criticisms of Goldschmidt’s hypothesis of macromutations. Goldschmidt had held that macromutations resulted from wholesale rearrangement of genetic material. Such mutations as these are almost invariably lethal to the organism in which they occur.

Although he does not use the word, Gould would have to be classified as an “emergentist” in philosophical biology. He continually stresses hierarchy in biological structure and function and is critical of reductionism—the attempt to explain wholes solely in terms of their parts and the denial of the existence of emergent or global properties found on higher levels of organization. As he puts it: “Different forces work at different levels.” He is critical of those who would, like Sir John William Dawson, attempt to reduce the external characteristics of an organism to explanation in molecular terms and who would thus claim to have explained the most complex structures, functions, and behaviors in terms of gene action alone.

There is a hazard in writing the type of biological essay that Gould writes so well. Readers possessing some familiarity with the biological sciences might find themselves wincing as they come across the occasional teleological statement, that the attribution of purpose to biological processes or to evolution. Leaving to one side the question of human motivation, apparently purposive biological phenomena can always be explained in functional language. The problem is that it takes more words to do so; but this is perhaps a minor quibble. Despite these minor lapses, Gould is clearly no vitalist. He rejects both the reductionist and vitalist alternatives in favor of the hierarchical view. Gould is no believer in vital forces as was Henri Bergson nor is he a believer in directed evolution as was the early evolutionary pioneer Chevalier de Lamarck.

Gould in his discussion of evolution could have tackled the question of whether there could be natural selection at the molecular level—whether there could be some sort of internal selection. It might well be that selection takes place inside the organism at the level of chromosome or gene. This would be consistent with Gould’s hierarchical approach and might be the source of his mutation producing the change early in embryological development that would culminate in great adult differences.

A fascinating story unfolds in Gould’s chapter on the Piltdown hoax. It will be remembered that the Piltdown affair was one of the most celebrated scientific hoaxes of this century. In Piltdown, England, a skull was planted so that it could be found. Without tracing tediously the entire story (which has been told many times before) Gould turns up what may be a new angle on the hoax—the possible involvement of the famous Jesuit paleontologist Teilhard de Chardin in the deception. Chardin was probably not involved in the manufacture of a skull from human and ape parts but may have participated in the planting of the pseudofossil. Gould draws some morals from the largely uncritical acceptance by eminent scientists of the genuineness of the fossil. Scientists are human and practice science in a social context. Piltdown man had to be genuine because England had to have had an early form of man. After all, had not the French found myriad prehistoric human remains and great abundances of prehistoric material culture? Species bias figured in as well. Humans are on top of the evolutionary heap because of large brains; ergo, Piltdown must be genuine for it had a large cranium. It was widely believed at the time of the “discovery” of Piltdown that the missing link would be discovered eventually and that a large brain case would be a prominent feature of such a fossil. Thus, Piltdown confirmed the prejudice of the theory dominant during the first three decades of this century.

Gould also deals with the science and politics of human differences. Scientists, even such famous scientists of the past as Baron Cuvier, have been guilty of asserting differences among races and between men and women and of using such alleged differences (of intelligence) as justification for racial and sexual discrimination and eugenics. Gould points out that it is not that there are no differences but that they are not of the kind that make any difference. In this area, Gould’s analysis is devastating. Time and again he shows that such science is done in a social and cultural context. Hence, it is not surprising that some so-called science was really an attempt to justify a belief in European or male superiority. Such science is, of course, circular (in the sense of a logical fallacy). The earlier scientific racists and sexists through the selective choice and selective interpretation of evidence found exactly what they were looking for. This same sort of pseudoscience goes on yet in the IQ controversy which has been fueled in our time by the evangelism of William Shockley.

Gould’s examples throughout are fascinating. He apparently loves those oddball characters in the living world, and their life-styles intrigue him. In fact, in the books’ first essay, “The Panda’s Thumb,” Gould makes the case for evolution through oddity. The panda’s thumb (not really a true thumb) is an adaptation to food supply. Other strange organisms with strange habits, structures, and functions with which he deals are turtles, anglerfish, bacteria, dinosaurs, and Mickey Mouse. The lesson to be drawn from oddity in the biological world is that people should not look for perfection there. It is not perfection that should be sought in the evolutionary process either, but rather the odd arrangements which are the “senseless signs of history” indicating evolutionary change.

Occasionally one will encounter some technical biological terms in the text but this should not put the reader off since, in almost all cases, Gould explains what they mean in ordinary language. So the reader should not despair the encounter with phyletic, allpatric, and the like. There is one minor slip. It was Francis Crick, not James Watson, who coined the phrase “Central Dogma of molecular biology.” The book has a bibliography and an excellent index.