‘Confusion Over Evolution’: An Exchange

To the Editors:

There are many points in Stephen Jay Gould’s curiously ill-tempered review of Helena Cronin’s The Ant and the Peacock [NYR, November 19, 1992] that I disagree with, but I will content myself with one. Cronin argues that the apparent altruism displayed by some animals (the Ant of her title) raised a question for Darwin that he was unable fully to answer, but which has been answered by a genecentred approach. Early in his review, Gould states that “the key question evoked by the ant’s altruism has not been resolved.” When I read this, I was puzzled: has Gould spotted a fallacy in the argument that I have missed? Not at all. It later turns out that Gould fully accepts Cronin’s explanation of the social behaviour of ants in terms of the genetic relatedness between the members of a colony, an explanation first proposed by W. D. Hamilton. So why has the question not been resolved?

It turns out that the failure is no more than this; the gene-centred argument cannot explain human altruism, which is often directed to non-relatives. Coming from anyone this argument would be odd, but from Gould it is astonishing. For years he has been inveighing against those who regard evolution as an inevitable progress culminating in man, and emphasizing the marvellous diversity of life. Now he tells us that a biological argument fails if it cannot fully explain some feature peculiar to humans. If so, I have wasted my life, and so, for that matter, has Gould. As it happens, I agree with him that there is more to the evolution of human altruism than kin selection: once a species has acquired language as a second method of passing information between generations, new mechanisms of change become possible. But to dismiss half of Cronin’s thesis on these grounds is ridiculous.

Professor J. Maynard Smith

School of Biological Sciences

University of Sussex

Brighton, England

To the Editors:

As an educator, Stephen Jay Gould has illuminated literally hundreds of dark corners of biology for us all, but he is also a formidable polemicist whose campaigns have blighted more than a few reputations and careers. There is a delicious irony, therefore, in his desperate attack on Helena Cronin’s The Ant and the Peacock. For years he has tried to divert our attention from the “Panglossian” strategic principles of adaptationism, and now he has stubbed his own toe on one of them: if an organism has one trick that it always uses, chances are that eventually the evolving world will catch on and expose it to counter-measures. Gould’s trick is refutation-by-caricature, and this time he exposes himself with stunning efficiency, even candidly admitting, at one point, that in the past he has stooped to caricature of the opposition.

Gould’s basic trick, honed over the years, has a nifty second stage. In the first stage, you create the strawperson, and “refute” it (everybody knows that trick). Second (this is the stroke of genius), you yourself draw attention to the evidence that you have taken the first step—the evidence that your opponents don’t in fact hold the view you have attributed to them—but interpret these citations as their grudging concessions to your attack!

The trick becomes transparent with overuse, however, and Gould has managed to epitomize his career with this ploy in the confines of a single article. Here are three distinct instances.

(1) He correctly identifies Cronin as belonging to the school of his nemesis, Richard Dawkins (hence the vituperation). He characterizes Dawkins’ “genic selectionism” as “hyper-Darwinian reductionism” and attributes to him (without citation) the view that the gene’s perspective is “exclusive,” which apparently means that genic selectionism is held to be “the fully comprehensive theory of biological change.” But it is Gould, not Cronin or Dawkins, who makes this “strange assertion.” Instead of bothering to refute this straw doctrine, Gould refers the reader to “sharp and devastating criticism both from biologists and philosophers.” Many of us who know the literature he cites would not describe it in those terms. For an accessible and trenchant antidote to Gould’s over-statement, see Philip Kitcher and Kim Sterelny, “The Return of the Gene,” Journal of Philosophy, 1988, pp. 339–361. In any event, with breathtaking chutzpah, he then describes Dawkins’ The Extended Phenotype (1982) as containing a “fatal concession,” a “stunning admission of relativism that flatly contradicted Dawkins’ previous claim for true and exclusive causality at the genic level.” So are we to believe that Dawkins admitted defeat in 1982, and Cronin, a close colleague in the same department, hasn’t yet noticed, and continues to sing the song he abandoned a decade ago? Gould never quotes an instance of her commitment—or Dawkins’ commitment—to the caricature he foists on them. In fact, Dawkins himself regards The Extended Phenotype as anything but a pulling back. He sees the book as a more radical extrapolation of the now widely accepted thesis of the selfish gene.

(2) Gould characterizes adaptationism as “pure adaptationism” and “panadaptationism”—which is apparently the view (he never defines it) that every feature of every organism is to be explained as an adaptation selected for. But Cronin herself is particularly acute in criticizing this view (pp. 66–110) and, in particular, one of Gould’s earlier misconstruals:

…Stephen Gould talks about “what may be the most fundamental question in evolutionary theory” and then, significantly, spells out not one question but two: “How exclusive is natural selection as an agent of evolutionary change? Must all features of organisms be viewed as adaptations?” (Gould 1980, p. 49, my emphasis). But natural selection could be the only true begetter of adaptations without having begot all characteristics; one can hold that all adaptive characteristics are the result of natural selection without holding that all characteristics are, indeed, adaptive. (p. 86)

I will play Gould’s second card for him here, so you can see the strategy in its purest form: Don’t you see? She has to admit that her panadaptationism can’t explain everything!

(3) The most transparent case is Gould’s invention of “extrapolationism,” described as a logical extension of “Cronin’s adaptationism.” This is a doctrine of pan-continuity and pan-gradualism that is conveniently—indeed trivially—refuted by the fact of mass extinction. “But if mass extinctions are true breaks in continuity, if the slow building of adaptation in normal times does not extend into predicted success across mass extinction boundaries, then extrapolationism fails and adaptationism succumbs.” I cannot see why any adaptationist would be so foolish as to endorse anything like “extrapolationism” in a form so “pure” as to deny the possibility or even likelihood that mass extinction would play a major role in pruning the tree of life, as Gould puts it. It has always been obvious that the most perfect dinosaur will succumb if a comet strikes its homeland with a force hundreds of times greater than all the hydrogen bombs ever made. There is not a word in Cronin’s book that supports his contention that she has made this error. If Gould thinks the role of mass extinctions in evolution is relevant to either of the central problems Cronin addresses, sexual selection and altruism, he does not say how or why. When Cronin turns, in her last chapter, to a fine discussion of the central question in evolutionary theory she has not concentrated on, the origin of species, and points out that it is still an outstanding problem, Gould pounces on this as a last minute epiphany, an ironic admission of defeat for her “panadaptationism.” Preposterous!

What irks Gould the most, he makes clear, is Cronin’s claim that what she is describing and defending is “modern Darwinism,” whereas he claims that “the main excitement in evolutionary theory during the past twenty years” has been “the documentation of the reasons why Darwin’s crucial requirement for extrapolation has failed.” Gould is referring, of course, to the whipped-up brouhaha surrounding his own three false-alarm “revolutions” in Darwinism: exaptation, punctuated equilibrium, and, most recently, species selectionism.

The Ant and the Peacock is scholarly and insightful, witty and vivid without being bullying. Gould’s review of it contains other mistaken objections and misrepresentations, but these three cases will do handsomely to disarm the rest.

Daniel C. Dennett

Center for Cognitive Studies

Tufts University

Medford, Massachusetts

Stephen Jay Gould replies:

In reading these two critiques, I can only perceive myself on the receiving end of a good-cop-bad-cop grilling. I therefore begin my defense by epitomizing my assessment of Helena Cronin’s book: She argues that gene selectionism is the key ingredient of a major revolution (she calls it “modern Darwinism”) that has reshaped our view of evolution by recognizing that genes, rather than organisms (as Darwin held), are primary units of natural selection. She symbolizes the supposed success of this revolution by the two chief problems putatively solved (sexual selection as displayed by the peacock, and altruism as illustrated by the ant). I summarized the philosophical and empirical arguments that have convinced most of my colleagues that exclusive gene selectionism is both logically and factually wrong, and I supported the hierarchical model that views selection as acting simultaneously at a variety of levels in a genealogical sequence of gene, organism, population, and species. I then argued that the ant and peacock do not support Cronin’s scheme because sexual selection (the peacock) can be resolved at the conventional Darwinian level of selection on organisms, while gene selectionism, though successful in explaining many cases of animal altruism (including the ant) cannot render the distinctive human form that set the philosophical problem in the first place. Finally, in reviewing two other books by paleontological colleagues, I argued that short-term selection in populations (at any level) cannot explain major geological patterns in the history of life.

My dear colleague and good-cop John Maynard Smith (who wrote the preface to Cronin’s book) only reiterates a point that I made myself (though with a markedly different slant). I allowed that gene selectionism has resolved many cases of animal altruism and I praised Cronin’s consideration of this issue by writing: “I agree with Cronin up to a point, and I greatly appreciate her incisive treatment.” Now, in most cases, I would concur with Maynard Smith that a claim for human difference only represents the peculiarity of an odd species, and shouldn’t rain on the parade of a general evolutionary solution. But altruism falls into a different category of intrinsically human conundrums because its classical moral and philosophical focus has not been addressed by the evolutionary solution: why are humans so prone to perform acts that both benefit others and endanger themselves. The evolutionary argument holds that animals perform such altruistic acts toward relatives who share enough of their genes to render the potential sacrifice beneficial to the altruist’s genetic heritage. But since most human acts of altruism are performed in the service of non-kin, this explanation cannot hold for our brand (as Maynard Smith agrees).

Within the little community of professional evolutionists (that John and I proudly call our own), the gene-selectionist account of “altruism” matters greatly, but we cannot and dare not claim that we have thereby solved the classic philosophical issue generally encompassed by this word. For we transmuted the vernacular word “altruism” to a quite different technical sense—and then solved the technical issue, leaving the human phenomenon (for which the word was invented) quite unresolved. If Cronin had only angled for the narrow technical sense, then I would have no beef; but she herself laid claim to the human prize by writing as the longest chapter in her book: “Human altruism: a natural kind?”

The less than collegial tone of Daniel Dennett’s commentary affirms the worst suspicions bruited in some quarters about the pungently rarified air of Cambridge, Massachusetts. (Thank God for Fenway Park and my local Bowl-a-Drome, where these mental pirouettes can be temporarily put aside and a semblance of populist normality attained.) Really, Dan, however much you may find my views on adaptation distasteful, why do you use this forum to air your personal grievances? Nearly all your commentary treats my doubts about adaptation. But I said scarcely anything about this subject in my review of Cronin (only one column of the fifteen devoted to her book, with further comments in the last section, four columns long, that treats the two other books). My commentary centers on her advocacy of gene-selectionism—and I criticize her from a standpoint within selection theory by defending the hierarchical concept described above. Since I am operating within selection theory, and selection generally leads to adaptation, my critique of Cronin does not involve those aspects of my work that you dislike (i.e., my doubts about organismal pan-adaptationism). Moreover, I devoted most space to logical and philosophical refutations of gene selectionism (the concept of emergence and the confusion of bookkeeping with causality). You are a professional philosopher; why did you not comment upon the bulk of the review at all?

Your three points supposedly seal my malfeasances, but none of your charges hold. You say I erected a strawman in stating that Cronin views genes as the only acceptable level of selection. But she says exactly this and I quoted her argument in my review (though you deny that I so cited her!):

Genes, then, can be replicators whereas organisms, groups and other levels of the hierarchy cannot. Natural selection is about the differential survival of replicators. So genes are the only serious candidates for units of selection.

Ipsa dixit.

My review treated three books—Cronin’s and two by my paleontological colleagues Peter Ward and Niles Eldredge. You accuse me of further unfairness to Cronin in the last section, which does not treat her work but discusses the good arguments of Ward and Eldredge against the extrapolationist model so vital to Darwin’s own world view (the rendering of geological pattern by successive accumulation of tiny generation-by-generation increments. To cite Darwin’s memorable words: “Natural selection is daily and hourly scrutinizing…every variation, even the slightest…. We see nothing of these slow changes until the hand of time has marked the long lapse of ages.”) Dennett writes: “I cannot see why any adaptationist would be so foolish as to endorse anything like ‘extrapolationism’ in a form so ‘pure’ as to deny the possibility or even likelihood that mass extinction would play a major role….” But Darwin himself took just such a position in trying to identify mass extinction as an artifact of an imperfect fossil record (see “On Extinction,” pp. 317–322 in the 1859 first edition of the Origin of Species: “we must remember…the probable wide intervals of time between our consecutive formations; and in these intervals there may have been much slow extermination”).

Dennett accuses me of advancing these paleontological claims only to toot my own horn—in his words the “whipped-up brouhaha surrounding his own three false-alarm ‘revolutions’ in Darwinism: exaptation, punctuated equilibrium, and, most recently, species selectionism.” But my paleontological arguments in the review do not mention any of these themes (which are central to my view of life). I wrote instead about the neutral theory of nucleotide evolution and of mass extinction—and I have done no research on either of these subjects (though I greatly appreciate what my colleagues have accomplished in these areas).

Dan, the letterhead of your stationery carries the motto of your university: pax et lux. Your unfair and unkind comments proffer precious little of the first, and therefore provide about as much of the second.