Unofficial SJG Archive

The Unofficial Stephen Jay Gould Archive

Unofficial SJG Archive

Speaking Out for Paleontology  (excerpt)

by Michael Ruse

arly in December of 1981, the federal courtroom in Little Rock, Arkansas, was packed. It was the first week of a trial brought on by the American Civil Liberties Union to challenge the constitutionality of a state law passed earlier that year. The law mandated "balanced treatment," in the publicly supported schools, between evolutionary ideas and so-called Creation Science, better known as the early chapters of Genesis taken absolutely literally (Ruse 1988). By the end of the third day, the case for the plaintiffs was going well. Theologians had testified that Christianity had long interpreted the Bible metaphorically; a philosopher (me!) had argued that Creation Science fails every criterion of demarcation between science and pseudo-science; and the scientists were pointing to error after error in the claims of the literalists.

Out at supper that night, everyone started to relax, and the wine flowed freely. Someone struck up a hymn—one of those stirring melodies from the Baptist South—ironically at first, but before long all were joining in with vigor. No voice was louder than that of Stephen Jay Gould: paleontologist, skeptic, Jew, New Yorker, Harvard professor, baseball fanatic. But then, no voice is ever louder than that of Steve Gould, which is a major reason why he is the best-known evolutionist in America today.

Located in the Museum of Comparative Zoology at Harvard University, Stephen Jay Gould rivals Richard Dawkins in his fame as a popularizer of evolution. His Ever Since Darwin, a collection of essays published in 1977, was a bestseller, as have been several of his books since, especially Wonderful Life, his work on the long-lost organisms of the Burgess Shale, an outcrop in the Canadian Rockies. On the bestseller lists recently was Full House: The Spread of Excellence from Plato to Darwin, a work which shows how the nonexistence for nearly sixty years of .400 hitters in baseball has much to tell us about life's history.

Although this last work in particular was as popular as can be, Gould would be insulted and hurt were one to suggest that he is simply a writer and thinker of the public domain. He believes that he can straddle successfully the public and the professional, and would argue that as a professional evolutionist he is indeed making frontline advances. We shall have to consider this point. So for the moment, let us turn in a neutral fashion to Gould's work.

Gould began his career in the mid-1960s as a paleontologist specializing in the evolution of snails (Gould 1969). At this point, he was an orthodox Darwinian, who had written a review paper on problems of relative growth (a sometime interest of Julian Huxley, whose significance was acknowledged) showing how things considered nonadaptive can be fitted readily into a selectionist framework (Gould 1966). Soon, however, Gould was moving to make his own mark, most particularly with a fellow paleontologist, Niles Eldredge, in advocating a new paleontological theory of punctuated equilibria.

Together, Eldredge and Gould (1972) argued that the traditional synthetic theorist's vision of evolution as a smooth, gradual process, hidden only because of the incompleteness of the fossil record, is quite mistaken. The fossil record is not so very inadequate, and in any case there is theoretical reason to think that evolution will be jerky rather than smooth. "If new species arise very rapidly in small, peripherally isolated local populations, then the great expectation of insensibly graded fossil sequences is a chimera. A new species does not evolve in the area of its ancestors; it does not arise from the slow transformation of all its forebears." Hence, "The history of life is more adequately represented by a picture of 'punctuated equilibria' than by the notion of phyletic gradualism. The history of evolution is not one of stately unfolding, but a story of equilibria, disturbed only 'rarely' (i.e., rather often in the fullness of time) by rapid and episodic events of speciation" (84).

To make this case, Eldredge and Gould turned to the writings of Ernst Mayr (1959, 1963), who had proposed the so-called founder principle to explain speciation: a small group of organisms gets isolated; because of variation within the parent population, the group will have only a subselection of the total possible gene combinations; this will cause a rapid "shaking down" or "genetic revolution" among the members of the group as they learn to do with much less than the full complement; and so there will be rapid evolution to new forms.

I am not sure how far one would want to say that any of this was orthodoxly Darwinian. The founder principle seems to owe as much to Wright's notion of drift as to anything in the Origin. (Wright claimed it owed everything to his notion of drift.) Moreover, with the emphasis on speciation rather than adaptation, Eldredge and Gould were starting to think of life's histories less at the individual level and more at the group level—where overall patterns were to be understood through the dynamics of the arrival and disappearance of groups (what another evolutionist was to label species selection). But the general discussion was certainly placed in a Darwinian context, and at this point (1972) Gould was not setting himself up as a critic of the synthetic theory. He was merely arguing that people had not interpreted that theory properly when it came to macroevolutionary changes as shown by the fossil record.

However, as the 1970s rolled along, Gould started to get more and more uneasy with conventional Darwinism, especially with the assumption of ubiquitous adaptation. The main spur to skepticism undoubtedly was a massive reading program in the history of evolutionary thought that engaged Gould in preparation for a work he published in the same year (1977) as Ever Since Darwin. This book, Ontogeny and Phylogeny, part history, part science, argued that the much-despised connections between ontogeny (the course of development of an individual organism), especially in the embryonic stages, and phylogeny (the evolutionary development of a species) still have some worth; and in support he argued not only from evidence today but from the evidence of history. Since this history inevitably involved a great deal of German history, where the ontogeny/phylogeny analogy was taken most seriously, Gould immersed himself in that morphological tradition which had so infuriated Cuvier, Naturphilosophie: a holistic philosophy stressing that the most significant features of organic life are the isomorphisms which link organism to organism. Adaptation is in many cases secondary or nonexistent, and unity of type or Bauplan (to use the German term for organic groundplans or archetypes) is primary (Russell 1916).

This led Gould to write numerous articles hostile to ubiquitous adaptationism, including a celebrated attack coauthored with the population geneticist Richard Lewontin, in which attention was drawn to the nonfunctional parts of the tops of church columns (which he called "spandrels"; see figure), and the moral was drawn for organisms (Gould and Lewontin 1979). By 1980 Gould was ready for an all-out assault on adaptationism, and he declared the synthetic theory of evolution to be effectively dead. Gould's version of punctuated equilibria (Eldredge has always remained more orthodoxly Darwinian) was now edging close to saltations—macro-mutations—for those crucial rapid changes in the course of evolutionary history (Gould 1980a).

Moves of this nature did not find favor with more conventional Darwinians, especially those working experimentally on rapidly reproducing organisms where natural selection is a vital tool. It was pointed out that saltations have no empirical foundation and that, on macro-scales, selection can do just about anything that you could want (Stebbins and Ayala 1981). Although hardly acknowledged formally, we see a consequent rapid retreat by Gould to a position that is certainly not inconsistent with Darwinian selection. However, it is not a retreat to the original position. Now Gould (1982a) was (and would still claim to be) offering an "expanded" Darwinism. Natural selection and adaptation are undoubtedly important when one is considering organisms in their day-to-day life and microevolution. But as one looks at more long-term matters, one sees that other factors, including brute chance, come increasingly into play.

Instead of the unilevel synthetic theory, one now has a hierarchical theory, that is to say something (like the Catholic Church) with different levels. Down at the lowest level (the micro-level)—the level of immediate or short-term change—one has a Dobzhansky kind of evolution that is essentially a function of the genes under the control of natural selection and like processes. But then one has upper levels (the macro-levels), where one is thinking of evolution over long periods of time. Here one has different processes at work. This means that no one level (especially not the micro-level) is to be privileged (Gould 1982b). In the language often used in such cases, the upper levels cannot be "reduced" to the lower level, meaning (contra Dobzhansky) one cannot hope, to explain away everything at the upper, bigger levels by expressing them in terms of the lower, smaller level.

[ Michael Ruse, Mystery of Mysteries: Is Evolution a Social Construction, Cambridge, MA: Harvard University Press, 1999, pp. 135-138. ]

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