Darwin began the Origin of Species not with fanfare, but with fantails—pigeons, that is. He wrote in Chapter 1:

Believing that it is always best to study some special group, I have, after deliberation, taken up domestic pigeons…I have kept every breed which I could purchase or obtain…I have associated with several eminent fanciers, and have been permitted to join two of the London Pigeon Clubs.

The public often equates the best science with the biggest questions. Surely the heroes of science are those who dare to ask how the brain thinks and where the universe ends. Practicing scientists, though not unmindful of these deepest conundrums, know that such questions, however vital and thrilling, are vacuous (at least for now) if we have no examples for testing competing hypotheses and don’t even know where we might find them. Progress in science, paradoxically by the layman’s criterion, often demands that we back away from cosmic questions of greatest scope (anyone with half a brain can formulate “big” questions in his armchair, so why heap kudos on such a pleasant and pedestrian activity). Great scientists have an instinct for the fruitful and doable, particularly for smaller questions that lead on and eventually transform the grand issues from speculation to action. While Lamarck (though a great empiricist on other subjects) selected an armchair as the source for his evolutionary treatise, Darwin chose pigeons, and revolutionized human thinking. Great theories must sink a huge anchor in details.

Thomas Kuhn’s seminal work, The Structure of Scientific Revolutions, affected working scientists as deeply as it moved those scholars who scrutinize what we do. Before Kuhn, most scientists followed the place-a-stone-in-the-bright-temple-of-knowledge tradition, and would have told you that they hoped, above all, to lay many of the bricks, perhaps even set the keystone, of truth’s temple—the additive or meliorist model of scientific progress. Now most scientists of vision hope to foment revolution.

We are therefore awash in revolutions, most self-proclaimed—and we must therefore scrutinize the claims. Few proclamations have been more overt, few pursued with clearer aims in conscious sequence, than human sociobiology in the form proposed by the Harvard biologist Edward O. Wilson. The goal was audacious, but simply stated: to achieve the greatest reform in human thinking about human nature since Freud. The citadel must fall in stages to the battering ram of strict Darwinism. The first step was a chapter on the promise for a unified Darwinian theory of behavior, placed as a finale in Wilson’s great treatise The Insect Societies (1971). Then the general theory (1975), Sociobiology, the New Synthesis (an explicit manifesto of revolution for the cognoscenti, since we tradesmen of evolution call our own Darwinian orthodoxy, a legacy of perceived revolution during the 1930s and 1940s, “the modern synthesis”). As Insect Societies ended with a chapter on sociobiology, so Sociobiology ended with a chapter on Darwinian explanations of human behavior.

Sociobiology included a diagram with a clear martial metaphor; it showed the social sciences eviscerated and then absorbed—half-subsumed into neurobiology (as we understand how the brain works), the rest into Darwinian evolutionary theory (as we elucidate the value of behaviors in the ultimate Darwinian game of passing genes to future generations). Human nature would fall to the Darwinian tide in two stages. First, sociobiology tried to solve the easier problem of human universals, including gender differences that hold across cultures—the subject of Wilson’s first explicit book on human sociobiology, On Human Nature (1978). But a theory of universal behavior cannot be a comprehensive account of human nature; we must also encompass the differences among cultures, and the astonishing speed and lability of cultural change. Prima facie, the stately pace of Darwinian (genetic) change seemed a most unpromising source for locating the differences, but here’s the rub (or the “vaulting ambition” of Kitcher’s title): the greatest revision since Freud must be comprehensive. What good is a theory of human nature that cannot explain the differences among us? Thus the dubious final step had to be taken, and a theory of differences proposed (via feedback loops between genes and culture, for no one could attribute such speed in cultural change to genes alone). Lumsden and Wilson vested their final step in a deeply flawed and now discredited mathematical model in Genes, Mind and Culture (1981) and, shorn of equations for the layman, in Promethean Fire (1983).

But human sociobiology must be the most peculiar of self-proclaimed revolutions in science. We usually reserve the term for new structures of ideas, fundamentally new ways of knowing (like evolution versus creation by fiat, or quantum indeterminacy against the Newtonian machine). Human sociobiology, instead, only raided one field with the unmodified tools of another. Moreover—and here the precious irony—sociobiology wielded the most orthodox version of these tools at the very moment that its parent discipline, evolutionary theory, had begun a severe reassessment of the very principles invoked to fuel the revolution in human nature. Human sociobiology worked by pure extension of flawed (if broken) tools into uncongenial territory. Wilson’s martial metaphor may have been pure hubris, and quite mistaken—but it was certainly apropos.


As a severe critic of human sociobiology from its inception, I clearly am not an impartial observer. Yet surely the equation of bland nonpartisanship with objectivity—a silly notion fostered by the worst traditions of television news reporting—must be rejected. We may scrutinize a known critic more carefully, but ultimately we must judge his arguments, not his autobiography.

The debate on human sociobiology has been particularly murky because a legitimate political theme (misuse of genetic arguments to support existing social arrangements as biologically grounded) has accompanied a more interesting and abstract debate about modes of explanation from the start, a wrangle abetted by early Wilsonian statements that, to say the least, played poorly in feminist circles:

In hunter-gatherer societies, men hunt and women stay at home. This strong bias persists in most agricultural and industrial societies and, on that ground alone, appears to have a genetic origin…. My own guess is that the genetic bias is intense enough to cause a substantial division of labor even in the most free and most egalitarian of future societies…. Even with identical education and equal access to all professions, men are likely to continue to play a disproportionate role in political life, business and science. 1

Philip Kitcher has, I think, properly located the legitimate political issue as the greater care that should be demanded of those who choose to speculate when the consequences of confusing fact and guess are severe:

The true political problem with socially relevant science is that the grave consequences of error enforce the need for higher standards of evidence. In the case of pop sociobiology, commonly accepted standards are ignored. The mistakes merely threaten to stifle the aspirations of millions.

The dismissal of critics as politically motivated may bear some force as rhetoric for a counterattack, but such a defense only cheapens a fascinating intellectual debate. We raise the political point because it cascades from poor science.

Philip Kitcher and I approach the criticism of human sociobiology quite differently, though we share a basic attitude. I believe that the methods and arguments of this field rest upon a central flaw. I think (as I shall explain more fully later in this review) that the flaw lies in exporting to the analysis of human behavior the apparatus of the strictest form of Darwinian orthodoxy. That orthodoxy locates all evolutionary mechanics in the struggle among organisms for reproductive success. In Darwin’s world, the calculus of success is simple—winners pass more copies of their own genes into future generations, nothing else. The theory has no space for such concepts as “the good of the species” or “the harmony of ecosystems,” except as epiphenomena of the primal struggle for personal reward. This central character of Darwinism explains why sociobiologists have taken altruism as the test case for their approach—for, prima facie (though realities are deeper than appearances), acts of altruism could not be selected in Darwin’s world, since they harm individuals, whatever they may do for species. Thus, if the phenomenon that seems contrary can be rendered as consistent—by arguing, for example, that altruistic acts may save enough relatives to pass on sufficient copies of the altruist’s genes—the general theory achieves stunning support through resolution of paradox.

The central flaw in sociobiology results from this Darwinian premise: the different kind of behavior the theory purports to explain must be interpreted as adaptations of organisms. At a time when evolutionary theory rings, above all, with criticism of these very notions, revolutions based on selectionist orthodoxy seem curiously anachronistic. Exclusive focus on organisms has been challenged by a hierarchical theory that grants equal weight to selection as acting upon other entities of the genealogical hierarchy—genes and species, for example. Strict adaptationism has faltered badly as better understanding of genetic and developmental architecture forces us to view the parts of organisms as integrated into systems constrained by history and rules of structure, not as a set of tools, each individually honed to benefit organisms in their immediate ecologies.

Kitcher, on the other hand, takes another tack, and he has nearly convinced me. In a crowded literature (much of it quite good amid the mindless polemics and speculations), Vaulting Ambition is unquestionably the best criticism of human sociobiology that I have read. Kitcher argues that human sociobiology has no rigorous central core, that it represents a set of indifferent and largely speculative studies loosely coordinated by a common commitment to cardboard Darwinism. As such, it is slippery and elusive. It cannot be judged as an entity because it lacks coherence. Therefore, any proper assessor must undertake a patient dissection, case by case, until at the end nothing concrete remains to underpin the Darwinian superstructure. Darwin could invoke one hundred breeds of pigeons to support his theory of selection; human sociobiology is left with a single, flightless (and extinct) species of that ilk—the dodo. Kitcher writes:


If we could expose one error underlying all the faulty analyses of human social behavior, then it would not be necessary to proceed, as I have done, by examining example after example. Unfortunately, sociobiology is a motley. Not only is there no single monolithic theory to be scrutinized, but the individual Darwinian histories offered by pop sociobiologists may be flawed in any of a number of different ways. There is a family of mistakes, and in distinct examples distinct members are implicated.

As a philosopher of science with strong skills in mathematics and a good back-ground in evolutionary theory (he has also written the best book on creationism, Abusing Science), Philip Kitcher is uniquely qualified for this dissection. I admire most of all—for such diligence is rare in our frenetic world—the simple patience that Kitcher has mustered to invest such attentive care in the intricate details of case after case. A number of critics, myself included, might have done so before, but we didn’t have the gumption or the endurance once it dawned upon us that no shortcuts could be found. No critique is so damning as the sequential removal of examples, one after the other, for as Mies van der Rohe proclaimed in my absolute favorite among mottoes: God dwells in the details.

But Kitcher also uses the special tools of his profession. I much appreciated the traditional skill of a trained philosopher in defining and dissecting arguments—particularly in the last chapter where I finally learned to define properly what had bothered me intuitively about the false bridges constructed by sociobiologists between Darwinian imperatives and human ethics. More important, Kitcher commands the mathematical skills to expose the fallacies and false assumptions of the apparatus needed by Wilson to complete his putative revolution—a model to explain differences among societies as anchored in genes and their interaction with culture. (These and other complex quantitative analyses are wisely separated from the text as boxes, and do not obstruct the flow of argument for nonmathematical readers. But please don’t skip these sections if you can handle them; as I said above, the strength of this book lies in its mastery of details.)

Kitcher’s critique begins with two crucial distinctions—first between broad and narrow sociobiology. Clearly, there must be a potential evolutionary science of behavior. If we wish to call this enterprise sociobiology (broad version), then no right-thinking person can oppose it. Kitcher’s critique centers upon the narrow version, described above and vested in the strict Darwinism of natural selection working on items of behavior for their benefit in increasing the reproductive success of individuals.

Kitcher correctly notes that the narrow theory has no separate intellectual status—it is no more nor less than ordinary strict Darwinism applied to items of behavior instead of the shapes of bones and the colors of wings:

As we approach, the “new synthesis” turns out to be a mirage. There is no autonomous theory of the evolution of behavior. There is only the general theory of evolution….

The problems faced by the aspiring sociobiologist are just those of other evolutionary biologists. Writ large.

For this reason, I have maintained that the failure of human sociobiology is not so much the intransigence of Homo sapiens as the increasing inadequacy of strict adaptationism as a general approach to evolution, exacerbated by some special problems (see below) posed by our own species.

The second distinction contrasts sober with pop sociobiology. Kitcher defines the latter, the subject of his critique, as: “appealing to recent ideas about the evolution of animal behavior in order to advance grand claims about human nature and human social institutions.” Pop (or popular) sociobiology does not designate what journalists and science writers do, in contrast to the work of academic scientists, for Kitcher takes no cheap shots and his targets are all prominent professional biologists. It would also be a great mistake to equate sober versus pop with studies of other animals versus speculations about humans. Pop sociobiology is a style of speculative adaptationism equally applicable to herons, hamadryas baboons, and human beings. The issue is not taxonomy, but methodology. Studies of “rape” in mallard ducks and “adultery” in mountain bluebirds can be as pop as sociobiological arguments about human aggression.

Nonetheless, most sober sociobiology (applauded by all evolutionary biologists) treats nonhuman animals, while the worst excesses of pop sociobiology afflict Homo sapiens. Humans are particularly subject to the pop variety (speculative, storytelling adaptationism) for many reasons, three most prominent among them: (1) We have so little data about a slow-breeding species that cannot be overtly manipulated for experimental purposes. (2) The nongenetic process of cultural evolution often mimics the results of Darwinian (genetic) adaptation. In other species, limited consciousness guarantees that good behavioral design be shaped by evolutionary forces. Humans may devise good solutions without waiting for new genetic propensities, and then teach them to their kids and neighbors. Cultural evolution is not even a good analogue to biological evolution because it proceeds so much more rapidly and, especially, because it works by amalgamation and coalescence across lineages—the very topology precluded on the Darwinian tree of continuous divergence. Thus we cannot even use the sociobiological models as good metaphors or analogies. (3) Our inordinate interest in Homo sapiens, and the attention that any new speculation receives, goads us on to behavior that we would not countenance in studies of other species.

Sociobiologists often accuse their critics of falling into the oldest of Western cultural traps—the desire to keep humans apart from nature and free from her mechanisms, but Homo sapiens is not the only, simply the most prominent, victim of pop sociobiology.

Kitcher proceeds relentlessly through the bestiary of human sociobiology, beginning with its general premises and the apparatus of Darwinian theory, and proceeding through the (logically prior) examples of evolutionary universals in human behavior—aggression, incest avoidance, gender differences, for example—to later claims for explanations of cultural differences, and ending with a chapter on the biological ground of ethics. He identifies a standard chain of invalid inference as “Wilson’s ladder” and then proceeds to extirpate the rungs, case by case.

The ladder has four rungs, each subsequent step a dubious ascent from the perch below. Step one holds that we can use the general method for analyzing adaptation to argue “that all members of a group G would maximize their fitness by exhibiting a form of behavior B in the typical environments encountered by members of G.” Step two claims that “when we find B in (virtually) all members of G, we can conclude that B became prevalent and remains prevalent through natural selection.” I maintain that the ascent from step one to step two is the crucial weak link in adaptationist argument. The connection cannot be asserted a priori (though it often holds and can be affirmed by a panoply of methods devised by evolutionists for the experimental and inferential study of adaptation. Unfortunately these methods, often requiring manipulation of breeding and environment, cannot usually be applied to Homo sapiens, hence the particular dilemma of this weak link for human sociobiology).

The automatic ascent from step one to two is a logical fallacy central to the adaptationist program: the confusion of current utility with historical origin. The mechanic’s seal of current approval does not imply past construction for contemporary usage. Unfortunately, we call both the state of good design and the process of its origin by the same name—adaptation. The false equation of one with the other is, in my view, the Achilles heel of human sociobiology. Belief in a higher power is, no doubt, markedly functional, even adaptive in evolutionary terms, for many people, but we cannot conclude from its current benefit that such a belief arose by natural selection directly for religious ardor, nor can we infer that such belief is a genetically grounded entity at all (another requirement for Darwinian argument).

Step three holds that “because selection can only act where there are genetic differences, we can conclude that there are genetic differences between the current members of G and their ancestors (and any occasional recent deviants) who failed to exhibit B.” My example of religious ardor above (in this piece, that is, not the heavens) illustrates the fallacy of this connection. Behavior that works need not have a specific genetic ground, yet Darwinism is a theory of genetic change. Step four is the basis for political unhappiness with human sociobiology—the false equation of genetic grounding (itself unproved) with inevitability or resistance to change (many defects of vision are 100 percent heritable and easily corrected by a pair of glasses): “Because there are these genetic differences and because the behavior is adaptive, we can show that it will be difficult to modify the behavior by altering the social environment”—see the quotation from Wilson on page 47 for an example of this final fallacy.

If Wilson’s logic of argument follows a ladder, then his strategy for a revolutionary theory of human sociobiology (the greatest reform since Freud) mounts in a definite sequence as well—from the validation of strict Darwinian adaptationism as a proper approach to human behavior, to the explanation of universal behaviors, and finally to the elucidation of cultural differences. The critique of Wilson’s ladder questions step one of this strategy, but how does the sociobiological program deliver on its two empirical claims?

The debate on universals has properly centered on claims for adaptively based and genetically grounded differences between the sexes (an aspect of human social organization that transcends cultural particulars, according to supporters of sociobiological theory). The expectation for such sociobiological differences arises from the basic premise that all organisms, as the core of their being, must pursue the Darwinian imperative of individual reproductive success. In most animals, the argument goes, males and females must play the game differently, following the dictates of their biological roles. A sperm, little more than genes with a delivery system, is cheap to make, and each fertilization puts half of you into an offspring without further trouble. Thus, males should win their Darwinian edge by impregnating as many females as possible, as often as they can. This state of maximal spread may be achieved along a wide variety of routes, from stealth to outright domination—hence the variety of male strategies all tuned to one effect.

Females, on the other hand, invest much more by putting sources of nutrition into more expensive eggs; in addition, in many creatures, females bear offspring within their bodies and nurture their newborns for long periods. Hence, female investment must be prolonged and costly. Females receive no Darwinian edge in promiscuity since no gain in reproductive success attends any copulation after fertilization (while males can sew seed with their wild oats ad infinitum). Hence, female adaptations veer from profligacy toward care in choosing the best and most helpful males to father their offspring. The sociopolitical line of the pop argument now leaps from the page: males are aggressive, assertive, promiscuous, overbearing; females are coy, discriminating, loyal, caring—and these differences are adaptive, Darwinian, genetic, proper, good, inevitable, unchangeable….


We ought, however, to ask a more basic question before we assess this string of adjectives. Are the differences true? Do human males and females exhibit the predicted disparities? For if we cannot detect such universal distinctions amid the diversity of human cultures, what good can pop sociobiology provide? Its theory proclaims such differences as a fundamental prediction.

Myths of Gender by Anne Fausto-Sterling is a fine contribution to the empirical literature on human gender differences. If her argument is correct, then this fundamental sociobiological theory for human universals has failed, leaving very little of substance for the putative revolution. Myths of Gender is a courageous book, for it centers its conclusion upon the most undervalued and systematically ignored of all data—so-called null results.

Few people outside science (and not nearly enough people inside) recognize the severe effects of biased reporting. The problem is particularly acute, almost perverse, when scientists construct experiments to test for an expected effect. Confirmations are joyfully reported; negative results are usually begrudgingly admitted. But null results—the failure to find any effect in any direction—are usually viewed as an experiment gone awry. Meticulous scientists may publish such results, but they disappear forthwith from the secondary literature (and are almost never reported in the press). Most scientists probably don’t publish such results at all—who has time to write up ambiguous and unexciting data? And besides, they rationalize, maybe next week we’ll have time to do the experiment again and get better results. I call such nonreporting perverse because we cannot gauge its depth and extent. Therefore, we do not know the proper relative frequencies of most effects—a monumental problem in sciences of natural history, where nearly all theoretical claims are arguments about relative frequencies, not statements about exclusivity.

Over and over again in my career I have bashed my head against this wall of nonreporting. When Niles Eldridge and I proposed the theory of punctuated equilibrium in evolution we did so to grant such stasis in phylogenetic lineages the status of “worth reporting”—for such stasis had previously been ignored as nonevidence of nonevolution, though all paleontologists knew its high relative frequency. The critique of adaptationism fights a similar silence. A former student of mine recently completed a study proving that color patterns of certain clam shells did not have the adaptive significance usually claimed. A leading journal rejected her paper with the comment: Why would you want to publish such nonresults?

The study of gender differences suffers the same disabling bias. Measured differences are prominently reported, usually with much fanfare and much attention from the press. We really have no idea how often such differences are not found, for we don’t know what results are simply not published. But, at least, we might tabulate assiduously all reported studies, positive, negative, and null results. This difficult and ostensibly unrewarding task forms the core of Fausto-Sterling’s book on claims for differences in styles of intelligence and hormonally mediated disparities in behavior between men and women. Over and over again, she finds a disturbing pattern in the literature on “standard” gender differences. When differences are detected, they are usually in the direction proclaimed (though small); but the great majority of studies report no difference, and these have dropped from sight. (For example, the attribution of different cognitive styles to women as a result of less lateralized brains—i.e., less specialization between the two cerebral hemispheres—ranks among the most popular of current theories. Some studies find a small difference in this direction; none report more lateralized brains in women. But most experiments have detected no measurable difference in lateralization—and this is the dominant relative frequency that should be prominently reported.)

Moreover, measured differences often correlate well with immediate cultural distinctions, leaving little space for the sociobiology of genetically grounded adaptation. For example, poorer spatial perception is frequently cited as a different cognitive style for women. Fausto-Sterling shows that such differences show up in societies that greatly restrict the autonomy and physical movement of girls during early upbringing, but have not been detected in cultures (including Eskimos) that grant equal freedom to boys and girls. I need hardly say that this pattern, if as general as Fausto-Sterling suspects, would remove any empirical reason for invoking sociobiological explanations for the central issue in the study of human universals. Few general theories can survive the collapse of their crucial case.

If the sociobiological argument for universals fails, the more questionable extension to cultural differences hardly has a prayer of success. Kitcher’s most effective section—Chapter 10 on “the emperor’s new equations”—dissects the mathematical models developed by Lumsden and Wilson to close their system and complete the revolution. These models begin by acknowledging the obvious—that cultural differences are too rapidly developed to explain as genetically grounded adaptations. To save the Darwinian core of human sociobiology, they must be recast as the product of interaction between genes and culture—“gene-culture coevolution” in Lumsden-Wilson terminology. Thus even the labile and superficial vagaries of cultural shifts may be rooted in genetic adaptation promoted to speeds unattainable in Darwin’s world by positive feedback through cultural reinforcement.

This line of argument culminates in the “thousand-year rule” of Lumsden and Wilson—the claim that one millennium is short enough to fix such genetically grounded differences among cultures. Kitcher has waded through the obfuscation of their formalisms to show that the models can work only under assumptions so restricted and unrealistic that few or no real cultures could follow their dictates. In particular, people must change from one cultural practice to another only with extreme reluctance (for otherwise, the tie of gene to specific practice will be broken as obviously favorable practices spread like wildfire to all observant people, regardless of genotype). Furthermore, the difference in success of the two practices must be large (or else the change cannot occur in a mere millennium). But what difference so favorably large will be so resisted? Kitcher concludes:

The thousand-year rule is a theorem of the theory of gene-culture coevolution, when it is applied to the evolution of hypothetical people of extraordinary stupidity.

One begins to think that the entire revolution of human sociobiology now lies bereft of more than cloaking equations; its empirical underclothes are also missing—and it’s a hard, cold world out there.

Avid adaptationists (A.J. Cain in particular) have charged that critics of sociobiology have sacrificed the known truth of adaptation’s hegemony in nature in order to provide self-serving arguments for pursuing a purely political dislike of sociobiology. If I may indulge one paragraph of autobiography, I can only maintain that, in my case, the location of strict adaptationism as the central fallacy of contemporary Darwinism had three major roots, two preceding sociobiology. The first arose from seven years’ composition of Ontogeny and Phylogeny (1977), and my growing respect for the great European structuralist literature on laws of form (dating to such seminal thinkers as Goethe and Geoffroy). The second developed from a series of technical articles, written with David Raup, Tom Schopf, Dan Simberloff, and Jack Sepkoski between 1973 and 1977, on ordered patterns in phylogeny that arise within purely random systems (but were previously attributed without question to Darwinian adaptation). Sociobiology did provide the third—as I struggled to understand what seemed so wrong about a speculative literature that reached conclusions about people so out of whack with my concepts of reality. We must not trivialize an issue so central and important as adaptationism with the cardboard notion that only base motives could inspire any opposition.

In any case, the charge that we have fallen into the oldest cultural trap of walling off Homo sapiens from the rest of nature, denying to people the evident Darwinian truths that we hold as self-evident for other animals, cannot be sustained for a simple reason: we question strict and speculative adaptationism just as strongly when its advocates never breathe a word about human beings and apply their methodology only to the brute creation.


Bettyann Kevles has written a lively book, marred only by an overarching commitment to adaptationism in the a priori mode.2 Females of the Species is a survey of how female animals in nature play the Darwinian game of struggle for personal reproductive success. It contains not a word about Homo sapiens, except to say that nature’s diversity precludes any hope for identifying any particular human propensity as the dictate of biology.

Nonetheless, this work concentrates on demolishing a reverse fallacy—the long tradition, now thankfully fading (with a substantial push to oblivion from this book), for interpreting what female animals do in the light of supposed role models imposed by sexist societies upon human females. Males in nature had often been viewed as the sole contestants in Darwin’s game—endlessly scrapping, sneaking, pawing, and roaring for success in mating. Females, if considered at all, were often viewed as passive acceptors of male victory (usually, females were just left out, or imagined as sitting by the hearth with kids, I suppose, while the boys were out hunting).

Yet Darwin himself, in establishing the notion of sexual selection (the real subject of his mistitled treatise, The Descent of Man), identified two components of the process, one male centered, the other female centered—male competition and female choice. Females may play as active and pugnacious a role as males in assuring their Darwinian heritage—by only consorting with acceptable males, and vigorously refusing all other propositions (often by rough rejection, not only by coy passivity). Yet even though the general theory had always featured equality in determination by females, few students of behavior (almost all, until recently, white males) paid much attention. Instead, they unconsciously viewed female society in nature as a mimic of sexist limits imposed on women by surrounding human cultures. Thus, for example, Solly Zuckerman’s famous study of baboon behavior at the Regent Park Zoo in London (done in the 1930s) detected a male pyramid with an “alpha” baboon dominant on top. He scarcely considered relations among females beyond the presumed subservience of a cluster about the alpha male. The females, in fact, have hierarchies as well, for equally compelling Darwinian reasons, but they remained below a projected line of vision.

Kevles surveys the animal kingdom to demonstrate by the most powerful tactic of all—an overwhelming list of documented examples—that females are as active as males in following the Darwinian imperative. Her concluding paragraph reads:

No one today would seriously suggest that female animals are mere egg repositories waiting for something to happen. Just as we are coming increasingly to appreciate the diversity of female roles in human society, so we are coming to understand the variety in the behavior of female animals—and to recognize females, as, at the very least, co-equal players in the evolutionary game.

The central argument of Females of the Species presents one aspect to celebrate, another to criticize. We students of natural history stoutly maintain that the beauty and virtue of our profession lie in the bounteous diversity of surrounding life; all things that can happen manage somehow to occur. Yet too many of our treatises (popular and technical) abandon this richness for abstraction, and use examples only sparely or to illustrate particular points, rather than simply to explore the boundaries of that wondrous range. Kevles has paid proper homage to nature. She introduces her subject with a minimalist ten pages of necessary generality, and closes it with three pages of warning about dangers of false extrapolation. In between, her text is an unrelenting bestiary of examples from beetles to baboons—hundreds and hundreds of tales about female behavior, organized in sections on courtship, mating, mother-hood, and sisterhood, and all aimed to reinforce the point that females participate in the Darwinian struggle for reproductive success as actively and as assiduously as males, only differently. Anyone can wax eloquent about diversity as nature’s theme; Kevles has sunk years of work into its documentation.

If we accept the premise that speculative storytelling in the adaptationist mode has been the primary weapon used by sexists to keep women in a subservient place, then we might combat such an argument in one of two ways. I think that Kevles has chosen the wrong path. One might, as Kitcher does, identify the fallacies of adaptationist methodology and call for a clean break with this invalid style of argument. Or one might, as Kevles does here (and as Hardy and others have pursued before), try to construct a “good” sociobiology that depicts the natural behavior of female animals in a more positive light.

Kevles is not unaware of objections to strict adaptationism, and she takes account of them in occasional warnings, as: “There is not necessarily a purpose for every current structure, or a functional reason for every contemporary gesture.” But when we read her copious examples, we are in Pangloss’s world. Everything done by or to females is right, for all natural forms and actions are molded by the exclusive source of evolutionary change—the Darwinian struggle among organisms for individual reproductive success. Kevles concludes, in her final summation before the epilogue: “All female behavior, like the actions of males of the species, is self-centered. Individuals use and abuse each other, depending on which kind of behavior will help them survive.”

Adaptation is a powerful force, but its sway is not exclusive—and we both cari-cature the process and ignore a central theme in current revisions of Darwinian theory when we equate adequate evolutionary reconstructions with our ability to tell a story about optimal behavior in the absence of definite evidence, and only because theory prefers this mode of argument, Kevles seems to feel that an evolutionist’s work is done when she has told a plausible story about adaptation, not (as I would maintain) when such a talk can be tested with definite evidence against reasonable alternatives.

To cite just a few examples among hundreds (most centered on the conventional strategy of showing that even the oddest and most improbable behavior, infanticide and cannibalism, for example, is also for the best):

(1) Kevles tells us that sex is “for” the production of variety in offspring to secure evolutionary futures in a changing world:

Let us assume along with Darwin that sexual variation permits a rapid accommodation to change of a cataclysmic type (though this is by no means a universally accepted explanation). For example, if the climate suddenly cools dramatically, those individuals with genes for thick fur will survive.

But you cannot sink one of the liveliest debates in all evolutionary theory into a parenthesis. Besides, Kevles’s adaptationist explanation for sex cannot be right, unless we totally misunderstand the nature of causality. In Darwin’s world, organisms can only be selected for immediate advantages, not for success in unknown futures. Asexual organisms produce clones of offspring, sexual creatures a variety. An invariant clone may succumb in toto, but some members of a varying array may squeak through a future stress. Thus survival of a family line in the face of catastrophe may be a consequence of sexual reproduction, but this cannot explain why sex evolved in the first place, or why it continues in balmy times. Kevles confuses results and causes, a standard fallacy of adaptationist argument.

(2) In many species, males “protect” their fertilizations by sequestering mates, or even plugging their genital orifices with a hard secretion. Kevles is sure that such behavior, since it exists, must also be good for females (how about the alternative that males struggle continually with females, and sometimes one or the other sex wins): “These females have, in effect, traded off a guarantee of safety and sustenance for their offspring in exchange for an end to ‘shopping around’ and freedom.” Her evidence is simple existence of the phenomenon. Whatever is, is right: “Although some of these arrangements seem unduly complicated, they apparently suit the females of the species, since they have acquiesced.”

(3) When males seem to lord it over females, we must, according to Kevles, probe behind appearance and interpret domination as a fair bargain, equally good for females. On mating plugs: “Those females that accept plugs seem to have evolved according to the rationale that it is a safer bet to retain the supplies of sperm they have rather than to keep copulating in the hope of finding fitter fathers for their offspring.” On reabsorption of fetuses from a previous copulation in the presence of higher ranking males: “She trades away certain fertilization with the sperm of a previous male for the opportunity to start the process all over with a seemingly better chance that her offspring will survive.”

(4) When cuckoo nestlings live parasitically in the nests of redstart warblers, they may kill the redstart babies, yet the redstart parents continue to feed cuckoos. One might think that cuckoos have simply out-maneuvered the red-starts, but Kevles insists that all this must be for the best for redstarts as well. If redstarts haven’t evolved mechanisms of defense or even of recognition, then pressures for such an adaptation must not be high after all, whatever the apparent benefit. If it isn’t there, it isn’t needed. Kevles writes: “Why have redstarts not evolved their own safeguards against the cuckoo’s intrusion? It may simply be that there are many more redstarts than cuckoos and the mortality rate is not high enough to have prompted the adaptation of defensive strategies.” But how about the alternatives that defense would be a fine thing indeed, but that redstart neurology precludes it, or that the situation has evolved too recently for a response to be noted?

(5) Cannibalism must be prudent eating for the evolutionary benefit of all, not signals gone awry. Thus when an infant’s bones turn up in the feces of a mother gorilla, we must assume (without any direct evidence) that the baby was doomed anyway, and that a good meal is better than nurturing a misfit:

When primatologist Dian Fossey discovered infant bones in the feces of a gorilla mother whose baby had disappeared, Fossey deduced that the infant must have been maimed or moribund, and thus what looks at first glance like “murder” becomes “mercy killing.” With the moribund infant out of the way, the mother will soon stop lactating, start cycling, and be able to become pregnant again.

It is all for the best; a Darwinian cipher is removed, and mom can start the evolutionary game anew.

Interestingly, Kevles is willing to ascribe cannibalism in zoos and laboratories to unnatural stress (“these events are unusual and probably pathological”), but similar occurrences in nature can only be active adaptations. Thus hunters have noted in some species of mammals that fathers sometimes eat newborns if mothers have been killed: “Without their mothers’ milk and care, the infants were doomed. The males’ action in killing and eating the cubs, be they the father or just a passerby, is seen simply as making the best of a bad situation.” (How about the alternative that males will always feed unless females are near to suppress them?)

(6) If males help in raising offspring, they must be able to ascertain that the offspring are truly their own, for otherwise they are wasting time in Darwin’s world (how about the alternative that females sometimes win this round and fool some nonfathers into caring?): “How they ascertain paternity is largely unknown. But they must have some way of judging because males in so many species do help, and selectively.”

(7) Kiwi mothers play no role in rearing after laying their egg. This must be for the best, even though we might think that further investment of their energies would be better. (But why does this situation pose a problem at all? Maybe this non-optimal system works just fine.) “The graybrown kiwi produces the largest egg relative to body weight of all birds, and perhaps that enormous yolk, good nutritious material, is all the mother can afford to contribute. For the male incubates the kiwi chick and rears it with no female help at all.” And so the observation of male rearing becomes, ipso facto, evidence of a best solution.

(8) On the Channel Islands, ring-billed gulls often form female-female pairs. Kevles suggests this homosexual bonding may be an adaptation for successful rearing when a promiscuous male flits momentarily from his own mate to fertilize one of the females: “It may be that homosexual pairing is a strategy that allows those extra females to get fertilized by promiscuous males and then to incubate their young as a mated couple.” How about the alternative that an instinct for pairing overcomes the Darwinian imperative for reproductive potential on islands, like these, with unbalanced female/male ratios?

One might say that such speculative fancies are harmless, however relentlessly pursued. Dulce est desipere in loco (“it’s fun to fool around once in a while”), as Horace wrote. But storytelling in the adaptationist mode is no mere indulgence, tolerable for its good cheer, whatever its shortcoming as an alternative to proper science. For the deep belief embodied in the method—the idea that evolution is a tale of sequential molding of parts to designs favored in local habitats—badly misrepresents the richness of evolutionary theory. Evolution is the quintessential science of history, and the hold of history lies exposed in myriad imperfections and compromises (Panda’s thumbs) featured by all organisms as legacies of their different pasts—while Panglossian adaptationism makes history irrelevant. If we inhabit the best of all possible worlds, we need not probe beyond or behind current function. Moreover, an atomistic theory of adaptive optimality denies the structural integration of organisms by interpreting each part as a separate puzzle in good design. An evolutionary theory that downplays both history and structure denies the very two subjects that make biology so special and interesting.

More basically, the Panglossian vision wallows in the most serious logical error of historical reconstruction, the same error that sinks human sociobiology—the equation of current utility with historical origin, or the idea that we know why a structure evolved once we understand how it works now. This error has extensive ramifications well beyond the confines of evolutionary theory. It invalidates, for example, the so-called anthropic principle now preached by some physicists and cosmologists who do not understand the lessons of history. The strong version of this principle holds, roughly, that since human life fits so intricately well into a universe run by nature’s laws (current utility), these laws must have arisen with our later appearance in mind (historical origin).

The fallacy of inferring historical origin from current utility is best expressed by noting that many, if not most, historical structures are co-opted from previous uses, not designed for current operations. Legs were fins; ear bones were jaw bones and jaw bones were gillarch bones; incipient wings could not power flight, but may have served for thermoregulation. In one phrase, this same error undermines the central claim of pop sociobiology. The human brain became large by natural selection (who knows why, but presumably for good cause). Yet surely most “things” now done by our brains, and essential both to our cultures and our very survival, are epiphenomena of the computing power of this machine, not genetically grounded Darwinian entities crafted specifically by natural selection for their current function. Pop sociobiology must stake a claim for unraveling the origins and meaning of human thought and behavior. But if most behaviors are co-opted epiphenomena, not selected entities, then sociobiological explanations in the adaptationist mode cannot touch them.

A great asymmetry (I am tempted to call it the great asymmetry) pervades evolutionary histories. I am willing to admit that harmful structures will be eliminated by natural selection if they cause enough distress. But the other flank of the argument is not symmetrical—it is not true that helpful structures must be built by natural selection. All manner of things are fit for other reasons. The continued success of flying fishes, as George Williams once noted, absolutely depends upon their propensity for falling back into the water after they emerge. But no one in his right mind would argue that mass was constructed by natural selection to ensure a timely tumble. Charles Darwin, who was not a mindless functionalist, but who struggled mightily to grasp the laws of structure, wrote (in arguing that unfused skull bones, though essential in permitting the large heads of mammalian neonates to pass through the birth canal, cannot be adaptations designed for this role):

The sutures in the skulls of young mammals have been advanced as a beautiful adaptation for aiding parturition, and no doubt they facilitate, or may be indispensable for this act; but as sutures occur in the skulls of young birds and reptiles, which have only to escape from a broken egg, we may infer that this structure has arisen from the laws of growth, and has been taken advantage of in the parturition of the higher animals.

Cardboard Darwinism—the central belief of pop sociobiology and the anchor too easily adopted for Kevles’s adaptationist stories—is a theory of pure functionalism that denies history and views organic structure as neutral before a molding environment. It is a reductionist, one-way theory about the grafting of information from environment upon organism through natural selection of good designs. We need a richer theory, a structural biology, that views evolution as an interaction of outside and inside, of environment and the structural rules for genetic and developmental architecture—rules set by the contingencies of history and physicochemical laws of the stuff itself. The downfall of pop sociobiology will be a small benefit of this richer theory; its chief joy will be the deep satisfaction of integration: environment and organism; function and structure; current operation and past history; the world outside passing through a boundary (whether the skin of an organism or the geography of a species) into organic vitality within.

This Issue

September 25, 1986