The Structure of Evolutionary Theory

by Stephen Jay Gould

  I don't want to advance the exculpating argument that all unfortunate parts of this debate can be traced to purely external and unpreventable press hyping, and that we and our colleagues, in arguing both for and against punc­tuated equilibrium, have always walked Simon-pure on the intellectual high road. I will discuss on pages 1010–1012 the extent to which our own actions may have contributed to the unseemly side of the discussion. But I do main­tain that this truly uncontrollable external context set the primary reason for extended and unwarranted emotionality over the subjects of punctuated equilibrium and macroevolutionary challenges to conventional Darwinism.

  Meanwhile, in a simultaneous unfolding of the tragedy and the farce (in contrast with the famous epigram that historical tragedies generally experi­ence later replay as farces), a truly risible episode of intense public discus­sion about punctuated equilibrium erupted in England. American creation­ism may not rank as a full tragedy, although any suppression of a cardinal subject in public schools surely qualifies as an academic equivalent of murder. By contrast, the great British Museum debate can only be viewed as comical. In an epitome that risks caricature — although the full story veered as close to pure absurdity, and therefore to unalloyed comedy, as anything I have ever witnessed in the sociology of science — the British Museum (Natural History) opened a new exhibit on dinosaurs, based almost exclusively on the rigid cladism espoused by the Museum curators. Beverly Halstead — a man who might be judged as utterly infuriating and even cruelly meddling had he not been so charming and so personally warm and generous — hated these exhib­its with all his heart, for Beverly was an unabashed Simpsonian and a devotee of adaptationist biology. So Beverly, following a uniquely British tradition for generating tempests in teapots by inflationary prose fashioned of pure bom­bast — just where do you think that Blake's famous lines about seeing the world “in a grain of sand” and heaven “in a wild flower” came from? — de­cided to float the following blessed absurdity, a guarantee of public attention rather than instant burial, in the letters column of the Times. He accused — and I swear that I do not exaggerate — the British Museum of foisting Marx­ism upon an unwitting public in this new exhibit, because cladism can be equated with punctuated equilibrium, and everyone knows that punctuated equilibrium, by advocating the orthodoxy of revolutionary change, repre­sents a Marxist plot.

  Well, the press bit, and a glorious volley of ever more orotund letters appeared, both in the general press and in the professional pages of Science, Nature, and the New Scientist. Since I don't wish to prolong discussion of this peculiar byway (I doubt that any of the Museum curators had any abiding in­terest in politics beyond the academy, or personally stood one inch to the left of Harold Wilson), and since this chapter represents my own partisan account, [Page 985] let me simply reproduce my own letter to Nature — part of the final volley, just before the editors wisely and forcefully cut off all further fulmination forthwith:

  Sir — I have been following the “great museum debate” in your pages with a profound sense of detached amusement. But as matters are quickly reaching a level of absurdity that may inspire me to write the 15th Gilbert and Sullivan opera, and as I am, in a sense, the focal point for Halstead's glorious uproarious misunderstanding, I suppose I should have my say.

  Halstead began all this by charging that the venerable Natural History Museum is now purveying Marxist ideology by presenting cladism in its exhibition halls. The charge is based on two contentions: (1) a supposed link between the theory of punctuated equilibrium, proposed by Niles Eldredge and myself, and cladistic philosophies of classification; and (2) an argument, simply silly beyond words, that punctuated equilibrium, because it advocates rapid changes in evolution, is a Marxist plot. For the first, there is no necessary link unless I am an inconsistent fool; for I, the co-author of punctuated equilibrium, am not a cladist (and Eldredge, by the way, is not a Marxist, whatever that label means, as if it mat­tered). Under cladism, branching events may proceed as slowly as the imperceptible phyletic transitions advocated by the old school. Punctu­ated equilibrium does accept branching as the primary mode of evolu­tion, but it is, fundamentally, a theory about the characteristic rate of such branching — an issue which cladism does not address.

  For Halstead's second charge, I did not develop the theory of punctu­ated equilibrium as part of a sinister plot to foment world revolution, but rather as an attempt to resolve the oldest empirical dilemma imped­ing an integration of paleontology into modern evolutionary thought: the phenomena of stasis within successful fossil species, and abrupt replacement by descendants. I did briefly discuss the congeniality of punctuational change and Marxist thought (Paleobiology, 1977) but only to illustrate that all science, as historians know so well and scientists hate to admit, is socially embedded. I couldn't very well charge that gradualists reflected the politics of their time and then claim that I had discovered unsullied truth...

  I saw the cladistic exhibits last December. I did not care for them. I found them one-sided and simplistic, but surely not evil or nefarious. I also felt, as a Victorian aficionado who pays homage to St. Pancras [a wonderously ornate late nineteenth century railroad station] on every visit to London, that most of the newer exhibits are working against, rather than with, the magnificent interior that houses them. But I would not envelop these complaints in ideological hyperbole; Halstead has said enough.

  We can best explore the consequences of this historically contingent con­text by examining the use of punctuated equilibrium in two domains that, [Page 986] in their contrast, span the range of public influence from the ridiculous to the potentially sublime: the political propaganda of creationist literature, and the developing treatment of punctuated equilibrium in journalism, and high school and college textbooks of biology.

  Creationist misappropriation of punctuated equilibrium

  Since modern creationists, particularly the “young earth” dogmatists who must cram an entire geological record into the few thousand years of a literal Biblical chronology, can advance no conceivable argument in the domain of proper logic or accurate empirics, they have always relied, as a primary strat­egy, upon the misquotation of scientific sources. They have shamelessly dis­torted all major evolutionists in their behalf, including the most committed gradualists of the Modern Synthesis (their appropriations of Dobzhansky and Simpson make particularly amusing reading). Since punctuated equilibrium provides an even easier target for this form of intellectual dishonesty (or crass stupidity if a charge of dishonesty grants them too much acumen), no one should be surprised that our views have become grist for their mills and skills of distortion. I have been told that Duane Gish, their leading propagandist, refers to his compendium of partial and distorted quotations from my work as his “Gouldenfile.”

  Standard creationist literature on punctuated equilibrium rarely goes be­yond the continuous recycling of two false characterizations: the conflation of punctuated equilibrium with the true saltationism of Goldschmidt's hope­ful monsters, and the misscaling of punctuated equilibrium's genuine breaks between species to the claim that no intermediates exist for the largest mor­phological transitions between classes and phyla. I regard the latter distortion as particularly egregious because we formulated punctuated equilibrium as a positive theory about the nature of intermediacy in such large-scale structural trends — the “stairstep” rather than the “ball-up-the-inclined-plane” model, if you will. Moreover, I have written numerous essays in my popular series, spanning ten printed volumes, on the documentation of this style of inter­mediacy in a variety of lineages, including the transition to terrestriality in vertebrates, the origin of birds, and the evolution of mammals, whales and humans — the very cases that the usual creationist literature has proclaimed impossible.

  To choose a standard example by the movement's “heavies” (Bliss, Parker and Gish, 1980, p. 60), the following text embodies the first standard error, while their accompanying illustration (Fig. 9-38) records th
e second error by equating punctuated equilibrium with the saltational origin of each verte­brate class (if anyone has any lingering doubt about the pseudoscientific char­acter of this movement, try to make any sense at all of this figure, a supposed expression of their proper practice of the graphical and quantitative ap­proach to science): “Gould and Eldredge state that fossils, like living forms, vary only mildly around the average or 'equilibrium' for each kind. But, they say, the appearance of a 'hopeful monster' can interrupt or 'punctuate' this equilibrium. According to the new concept of 'punctuated equilibrium,' fossils [Page 987] are not supposed to show in-between forms. The new forms appeared suddenly, in large steps.”

  We may at least label creationist Everett Williams as timely in adding the insult of misnaming to the injury of the same distortion in a 1980 newspaper column: “The latest version of the process is called 'punctual [sic] evolution.' In this version, evolution is seen as moving in giant surges and then becoming stagnant for eons.”

  A broadsheet from Hillsborough, North Carolina, entitled “Harvard scien­tists agree: Evolution is a hoax!!!” goes whole hog in assimilating us to its own version of the rock of (small) ages: “The facts of 'punctuated equilib­rium' which Gould, Eldredge, Stanley and other top biologists are forcing the Darwinists to swallow fit the picture that Bryan insisted on, and which God has revealed to us in the Bible. Every species of organism was separately cre­ated during the six 'days' of creation... This is the doctrine taught by Scrip­ture and by Cuvier (the father of paleontology) alike, and modern biology is forcing the Darwinists to accept it.”

  In The Genesis Connection, J. L. Wiester commits the same error of scaling (in maximal degree this time), and then also cites us as hidden supporters of his one true way: “The theory of punctuated equilibrium holds that life did not evolve in the slow uniform method that Darwin envisioned but rather in rapid evolutionary bursts of major change called adaptive radiations. The Cambrian explosion of marine life was such an adaptive radiation . . . The new theory of punctuated equilibrium brings the thinking of science remark­ably closer to the biblical view. It is notable that the more evidence scientists discover (or fail to discover), the closer scientific theory moves toward the un­changing biblical pattern.”

  9-38. Creationist distortion of punctuated equilibrium modified from original in “Fossils: key to the present” by Bliss, Parker, and Gish, 1980. They misdepict punctuated equilibrium as a saltationist theory, with all vertebrate classes arising in single steps, all at the same time.

  [Page 988]

  If observers ever hoped for more accuracy or fairness from “official” publications of the two largest creationist organizations in America (in contrast with the “independents” previously cited), they shall be disappointed. The Je­hovah's Witnesses journal Awake! reported on the Chicago macroevolution meeting in its issue for September 22,1981, rooting the story in error number one, the Goldschmidt equation: “This revised view of evolution is called 'punctuated equilibrium,' meaning one species remains for millions of years in the fossil record, suddenly disappears and a new species just as suddenly appears in the record. This, however, is not really a new proposal. Richard Goldschmidt advanced it in the 1930's, called it the 'hopeful monsters' hy­pothesis, and was much maligned for it. 'Punctuated equilibrium' is a much more impressive designation.”

  Writing in the September 1982 issue of Signs, the leading journal of the Seventh Day Adventists, H. W. Clark discussed the Arkansas creationism trial in terms of error number two, false upward scaling to denial of transitional forms between classes and phyla. Clark equated our punctuations with faunal breaks between geological periods. A sidebar then misnames the author as well as distorting the theory: “Thank you, Dr. Jay Gould: Dr. Jay Gould is the distinguished Harvard Paleontologist who has raised a storm in evolu­tionary circles with his new theory of 'punctuated equilibrium.' Without in­tending to do so, he has told the scientific world that Darwin was wrong and the creationists are right. Not that he planned to, of course! Darwin recog­nized that the theory of evolution needs an unbroken line of gradually chang­ing fossils. Now along comes Dr. Jay Gould and agrees with the creationists: the missing links aren't there and never were. Thank you, Dr. Gould!” You're quite welcome.

  On the same theme of shoddiness in supposed creationist “scholarship,” I was quite struck by a photograph, supposedly of me, that appeared in M. Bailey's creationist book for children (Greenhaven Press, 1990), Evolution: Opposing Viewpoints. The gentleman depicted sports a flowing beard and baldpate — while my head hair has a precisely opposite distribution. He is also considerably older (and, I fancy, a good deal uglier) than I. I finally realized that he is the 19th century robber baron Jay Gould (no relation, by the way).

  While America deals almost exclusively with creationists of the Protestant fundamentalist line (at least among the movement's chief political activists), other religions have their own similar crosses to bear. I was sent a 1983 Hindu version by one Satyaraja dasa entitled “Puncturing the jerk theory.” An article by Barbara Sofer in a recent issue of Hadassah Magazine reports on the rare phenomenon of Israeli creationism, and cites one adherent: “Schroeder points out that the newer theories of punctuated evolution come closer to the biblical description.”

  Such inane and basically harmless perorations may boil the blood, but creationist attempts to use punctuated equilibrium in their campaigns for suppressing the teaching of evolution raise genuine worries. Nonetheless, here we can fight back directly — and we have always won. Elijah, after all, [Page 989] taught us how to fight fire (or rather the inability of reprobates to kindle any real flame) with fire — and the splendid man cited by creationists as their own primary hero did promise that truth would make us free.

  In the Texas textbook hearings of 1984, for example, Mel and Norma Gabler, the infamous professional propagandists for forcing a right-wing evangelical agenda into textbooks, lobbied for four imposed changes in any evolutionary passages within biology texts. One of the items rested upon the second standard creationist mischaracterization of punctuated equilibrium: “There are systematic gaps in the fossil record, showing absences of inter­mediate links. Punctuated equilibrium was devised to explain these gaps. Therefore presentation of evolutionary lineages, such as from amphibians to reptiles to birds and mammals, cannot be supported with evidence. The text­books should be revised to reflect this understanding.”

  But our side holds a strong weapon in such public cases, for we can also testify, and therefore expose. We have never failed in these circumstances. The Gablers' proposal lost and the State of Texas endorsed good biology books.

  Given the power of the First Amendment, and the fairness and intellectual stature of federal judge William Overton, our success in overturning the Ar­kansas equal time law, in a trial held in Little Rock in late 1981, seemed as­sured. I can only regard my own role, as one of six expert witnesses for sci­ence and religion, as both minor and probably irrelevant to the inevitable decision. But I was able to speak for paleontology and to add our unique tem­poral perspective to the documentation.

  Clarence Darrow's scientific witnesses were not permitted to testify in the Scopes Trial of 1925. The Louisiana creationism law, the only other statute passed in modern times by a state legislature, and a virtual copy of the Arkan­sas law, was dismissed by summary judgment following our success in Arkan­sas, and was therefore never tried in court. The State of Louisiana appealed this case to the Supreme Court, where oral argument consumes but one hour, and only the principal lawyers may testify, with no witnesses called. There­fore, for the first and only time in American history, the Arkansas trial per­mitted full-scale testimony about creationism in a court of law. I feel honored that I had the opportunity to help present the case for evolution as natural knowledge, and for creationism as pseudoscience, in the only legal venue ever provided to experts in the relevant professions throughout this long and im­portant episode in 20th century American history.

&
nbsp; My testimony and cross examination at the Arkansas trial lasted for the better part of a day, and focussed upon two subjects: the absurdity of attrib­uting the entire fossil record to the single incident of Noah's flood (a favored creationist ploy for cramming the entire geological history of the earth into a mere 6000 years or so), and creationist pseudoscientific practice as illustrated by their clearly willful distortions of the theory of punctuated equilibrium. (We did not, in this trial, try to “prove” evolution — a subject scarcely in need of such treatment, and not for a court of law to adjudicate in any case — but only to expose creationism as a narrow form of dogmatic religion, masquerading [Page 990] as science in an attempt to subvert First Amendment guarantees against the establishment of religion in public institutions.)

  Creationists continue to distort punctuated equilibrium, but we continue to win by exposing them in fair forums. For example, in 1997, Rep. Russell Capps of the North Carolina General Assembly used a “standard” misquota­tion from one of my essays about punctuated equilibrium in arguing before the legislature for a law that would ban the teaching of evolution as a fact (al­though teachers could still present the subject as a hypothesis). I suspect that Capps simply lifted the quote from Duane Gish's Evolution: The Fossils Say No! (I do love that title!) and never read my essay, because his version used exactly the same deletions as Gish's. Rep. Bob Hensley, an opponent of the bill, asked for my aid, and I wrote a letter, which he read to the assembly, de­tailing this dishonest treatment of my writing. I stated, in part (letter of April 4, 1997):

  [My] article is not an attack on evolution at all, but an attempt to ex­plain how evolution, properly interpreted, yields the results that we ac­tually see in the fossil record. The first part of the quotation is accurate, but about rates of change, not whether or not evolution occurs. The sec­ond part of the quotation after the three dots — “it was never seen in the rocks” — seems then to deny that evolution occurs. But if you read my full text and look for the material left out, it is obvious that my word “it” refers to gradualism as a style of evolutionary change, and not to evolution itself. If one reads the rest of the essay, the intent is abundantly clear. For example, I state on page 182: “The modern theory of evolution does not require gradual change. In fact, the operation of Darwinian processes should yield exactly what we see in the fossil record. It is grad­ualism that we must reject, not Darwinism.” . . . Thus you can see that my essay actually says exactly the opposite of the false quotation cited by your colleague. This is so typical of the intellectual level of most creationist literature. Do we really want our students to be taught by this form of dishonest argument?