Hen’s Teeth and Horse’s Toes

by Stephen Jay Gould

  Evolutionary theory itself has an appropriately zoocentric core. General principles cannot arise from the behavior of a single species, yet all species must conform to the principles. The role of this mild zoocentricity in breaking down the sturdy picket fences that existed before Darwin’s time ranks as a great event in the history of human thought. But the zoocentric view can be extended too far into a caricature often called the “nothing but” fallacy (humans are “nothing but” animals).

  The simplistic accounts of human sociobiology now flooding popular literature embody this overextended version of zoocentrism. Sociobiology is not just any statement that biology, genetics, and evolutionary theory have something to do with human behavior. Sociobiology is a specific theory about the nature of genetic and evolutionary input into human behavior. It rests upon the view that natural selection is a virtually omnipotent architect, constructing organisms part by part as best solutions to problems of life in local environments. It fragments organisms into “traits,” explains their existence as a set of best solutions, and argues that each trait is a product of natural selection operating “for” the form or behavior in question. Applied to humans, it must view specific behaviors (not just general potentials) as adaptations built by natural selection and rooted in genetic determinants, for natural selection is a theory of genetic change. Thus, we are presented with unproved and unprovable speculations about the adaptive and genetic basis of specific human behaviors: why some (or all) people are aggressive, xenophobic, religious, acquisitive, or homosexual.

  Zoocentrism is the primary fallacy of human sociobiology, for this view of human behavior rests on the argument that if the actions of “lower” animals with simple nervous systems arise as genetic products of natural selection, then human behavior should have a similar basis. Humans are animals too, aren’t we? Yes, but animals with a difference. And that difference arises, in part, as a result of enormous flexibility based on the complexity of an oversized brain and the potentially cultural and nongenetic basis of adaptive behaviors—aspects of human construction that debar any zoocentric extrapolation from why some insects eat their mates to murder in human families.

  Ironically, the zoocentrism of human sociobiology is often an illusion hiding a precisely opposite mode of reasoning. I argued previously that “objective” systems are often unconscious masquerades that reflect our own prejudices and hopes imposed upon nature. Much of human sociobiology trades upon the idea that if distinctive human behaviors can be found, albeit in rudimentary form, among “lower” animals, then these behaviors must be “natural” in humans too, a product of biological evolution. Sociobiologists are often fooled by misleading external and superficial similarity between behaviors in humans and other animals. They attach human names to what other creatures do and speak of slavery in ants, rape in mallard ducks, and adultery in mountain bluebirds. Since these “traits” now exist among “lower” animals, they can be derived for humans as natural, genetic, and adaptive. But they never did exist outside a human context. If mallard males seem to force physically weaker females to copulate, what possible relationship, beyond meaningless superficial appearance, can such an act have with human rape? No one can argue that the two behaviors are truly homologous—that is, based on the same genes inherited from a common ancestor. If the similarity is meaningful, it can only be analogous—that is, reflecting different evolutionary origins but performing the same biological function. Yet mallard behavior is part of the normal repertoire and seems to have evident utility in increasing the reproductive fitness of males; while human rape is a social pathology rooted in power and powerlessness, not in sex and reproduction.

  Is this not mere pedantic grousing? Aren’t the human terms a cute, graphic, and acceptable shorthand for what we all recognize as a more complex reality? Not when a colleague describes aggressive responses of male mountain bluebirds toward other males in the vicinity of its nest with these words: “The term ‘adultery’ is unblushingly employed…without quotation marks, as I believe it reflects a true analogy to the human concept…. It may also be prophesied that continued application of a similar evolutionary approach will eventually shed considerable light on various human foibles as well.”

  Such an old story. We hold a mirror to nature and see ourselves and our own prejudices in the glass. Historical examples abound. Aristotle described the large bee that leads the swarm as a “king,” and this misidentification of the only sexual female around persisted for nearly two thousand years, at least to an Elizabethan madrigal I sang last week: “I do love thee as the spring/Or the bees their careful king” (careful, that is, in the old sense of caring, not the modern meaning of cautious). Zoocentric systems fail primarily because they never are what they claim to be. The “objective” animal behavior, under which they subsume human acts, is an imposition of human preferences from the start.

  The more venerable, anthropocentric systems at least have the virtue of explicit self-recognition. They take Protagoras seriously in his claim that “man is the measure of all things,” and falter only in the hubris of arguing that evolution undertook its elaborate labor of some 3½ billion years only to generate the little twig that we call Homo sapiens. Anthropocentric systems have been out of vogue among scientists, at least in England and America, since Darwin’s time, but one version enjoyed some spectacular popularity a few years back—the system of a man discussed in quite a different context elsewhere in this section, the Jesuit priest and distinguished paleontologist Pierre Teilhard de Chardin.

  When Teilhard died in 1955, his evolutionary speculations, long suppressed by ecclesiastical authority, saw light, and his best seller, The Phenomenon of Man, became a cult book of the 1960s. Teilhard’s florid and mystical writing is often more difficult to decipher than his role at Piltdown, but I believe that the general line of his argument can be simply expressed. (A convinced Teilhardian might brand me as a shallow, heartless scientist, unable to appreciate the profundity of Teilhard’s vision. But difficult, convoluted writing may simply be fuzzy, not deep. Teilhard’s vision is rich in scope and tradition—for it is an old argument clothed in new terminology—but the essence of his position can still be stated with everyday words.)

  Teilhard believed that evolution proceeds in a definite and irreversible direction. To understand the nature of that movement, we do not look back to the origin of life and its physical properties, but to the latest product—to Homo sapiens itself. For life has been moving in our direction from the start. The advance of life records an ever increasing domination of spirit over matter. This ineluctable increase in consciousness can be grasped by studying two of its material products: among lower animals, diffuse and simple nervous systems evolve into centralized organs (brains) with subsidiary parts; among higher animals, brains increase in size and complexity throughout evolution. In an autobiographical essay, Teilhard wrote:

  I never really paused for a moment to question the idea that the progressive spiritualization of matter—so clearly demonstrated to me by paleontology—could be anything other, or anything less, than an irreversible process. By its gravitational nature, the universe, I saw, was falling—falling forwards—in the direction of spirit as upon its stable form. In other words, matter was not ultra-materialized as I would at first have believed, but was instead metamorphosed in psyche.

  Human evolution is the culmination of this psychic advance. In the anthropocentric vision, life only makes sense in terms of its striving toward man. We are inextricably part of nature because nature has been yearning toward us from the start. In a 1952 manuscript on human socialization, Teilhard stated:

  Human evolution is nothing else but the natural continuation, at a collective level, of the perennial and cumulative process of “psychogenetic” arrangement of matter which we call life…. The whole history of mankind has been nothing else (and henceforth it will never be anything else) but an explosive outburst of ever-growing cerebration…. Life, if fully understood, is not a freak in the universe�
�nor man a freak in life. On the contrary, life physically culminates in man, just as energy physically culminates in life.

  Since evolution follows a directed path, the tree of life is not a randomly ramifying network, but a bundle of branches, tied by genealogy at their base, diverging during their history, yet always moving in the same basic direction. The energy of matter compels divergence; the force of increasing consciousness imposes a common upward advance. Related species should form a set of multiple, parallel lineages, each diverging and adapting to a local environment, but each gaining continually in its spirit/matter ratio. Teilhard wrote in 1922 that “evolution…resolves itself into innumerable lines which diverge at such length that they appear parallel.”

  With the appearance of man, evolution has reached a crux. Spirit has accumulated far enough to reach self-consciousness. Indeed, a new layer has appeared in the earth’s concentric structure. Teilhard praised the great Austrian geologist Eduard Suess for introducing the term “biosphere” as an addition to the traditional concentric layers of lithosphere and atmosphere. But consciousness, Teilhard argued, has added yet another layer: “the psychically reflexive human surface…the noosphere.”

  Teilhard describes the noosphere as a physical reality, as a thin and fragile layer, now spread throughout the earth following the emergence of human ancestors from Africa and their subsequent migration to all continents. He wrote in a 1952 manuscript: “Above the old Biosphere there is spread now a ‘Noosphere’. As to the material reality of this enormous event, there is nobody who will disagree.” In a posthumous essay published four years later, he described the noosphere as “the marvelous sheet of humanized and socialized matter, which, despite its incredible thinness, has to be regarded positively as the most sharply individualized and the most specifically distinct of all the planetary units so far recognized.”

  The emergence of a noosphere, now so thin and fragile, represents the turning point of universal evolution. Teilhard wrote in 1930:

  The phenomenon of Man represents nothing less than a general transformation of the earth, by the establishment at its surface of a new layer, the thinking layer, more vibrant and more conductive, in a sense, than all metal; more mobile than all fluid; more expansive than all vapor…. And what gives this metamorphosis its full grandeur is that it was not produced as a secondary event or a fortuitous accident—but in the form of a turning point essentially foreordained, from the beginning, by the nature of the general evolution of our planet.

  Evolution has now reached its halfway point. Heretofore, despite the progressive gain of spirit, matter has dominated and evolutionary lineages, although moving in the same general direction, have constantly diverged. But the noosphere marks the beginning of the dominion of spirit over matter. As spirit gains the upper hand, convergence shall begin. The fragile noosphere shall thicken. The direction of a billion years shall be reversed, and conscious lineages (within Homo sapiens at least) will begin to converge as spirit gains rapidly in its sway over matter.

  Convergence has already begun in the process of human socialization. In terms of vulgar mechanics, human cultural evolution may be a process different from Darwinian biological evolution, but both participate in a higher unity as sequential aspects of universal direction. Human socialization, Teilhard writes, has engendered “a vast and specific process of physico-psychical convergency…whose sudden appearance and acceleration in the course of the last century is perhaps the most revolutionary event registered so far in human history…. The human world is decidedly caught, today and forever, in an irresistibly tightening vortex of unification.”

  The rush to convergence must concentrate and accelerate until all spirit, freer and freer of encumbering matter, amalgamates at a single point that Teilhard called Omega, identified with God, and, so far as I can tell, conceived as a reality, not a metaphor or symbol. He describes this apotheosis, graphically if not with perfect clarity, in The Phenomenon of Man:

  Convergent movement will attain such intensity and such quality that mankind, taken as a whole, will be obliged…to reflect upon itself at a single point…to abandon its organo-planetary foothold so as to pivot itself on the transcendent center of its increasing concentration. This will be the end and the fulfillment of the spirit of the earth.

  The end of the world: the wholesale internal introversion upon itself of the noosphere, which has simultaneously reached the uttermost limit of its complexity and centrality.

  The end of the world: the overthrow of equilibrium, detaching the mind, fulfilled at last, from its material matrix, so that it will henceforth rest with all its weight on God-Omega.

  And so, evolution labored for billions of years, produced perhaps a hundred million species of plants, bugs, and worms along the way, all to achieve, through the agency of one species endowed with consciousness, the union of spirit with God in splendid concentration at the point Omega. All previous life existed for us and for what we could become. Like the floating fetus that embodies the promise of futurity at the close of 2001: A Space Odyssey, we (or rather our thickening spirit layer, soaring upward) are the heirs and purpose of all previous life. This is the anthropocentric vision with a vengeance.

  What can one say to such a scheme? Would it be too literal and mean spirited to argue that it seems to fail at its only points of testable contact with the fossil record? Few paleontologists can discern any general, much less inevitable, trend to increasing braininess in the history of life. Most animal species are insects, mites, copepods, nematodes, mollusks, and their cousins, and I, at least, can see no pervasive trend among them toward the domination of matter by spirit. And the evolutionary tree does look more to me like a complexly wandering and ramifying bush than a bundle of parallel twigs growing upward in a definite direction. Of course, I realize that Teilhard used the term evolution in a metaphysical sense to identify the laws of cosmic progress, not in our usual sense to specify the mechanics of organic change (which Teilhard recognized and studied, but called transformisme). Teilhard’s technical works in paleontology are sound and solid, but they deal with transformisme and exist in a world of discourse quite separate from his anthropocentric vision of cosmic evolution.

  Perhaps the problem with all these visions—zoocentric as well as anthropocentric—is our penchant for building comprehensive and all-encompassing systems in the first place. Maybe they just don’t work. Maybe they must be defeated by the inherent complexity and ambiguity of our place in nature. How can we erect a picket fence when humans are so inextricably bound in nature? But how can we opt for complete continuity, either by working up from other animals (zoocentric) or down from humans (anthropocentric) when humans are so special, for better or for worse? We are but a tiny twig on a tree that includes at least a million species of animals, but our one great evolutionary invention, consciousness—a natural product of evolution integrated with a bodily frame of no special merit—has transformed the surface of our planet. Gaze upon the land from an airplane window. Has any other species ever left so many visible signs of its relentless presence?

  We live in an essential and unresolvable tension between our unity with nature and our dangerous uniqueness. Systems that attempt to place and make sense of us by focusing exclusively either on the uniqueness or the unity are doomed to failure. But we must not stop asking and questing because the answers are complex and ambiguous. We can do no better than to follow Linnaeus’s advice, embodied in his description of Homo sapiens within his system. He described other species by the numbers of their fingers and toes, their size and their color. For us, in place of anatomy, he simply wrote the Socratic injunction: Know thyself.

  5 | Science and Politics

  19 | Evolution as Fact and Theory*

  KIRTLEY MATHER, who died last year at age ninety, was a pillar of both science and Christian religion in America and one of my dearest friends. The difference of a half-century in our ages evaporated before our common interests. The most curious thing we shared was a battle we ea
ch fought at the same age. For Kirtley had gone to Tennessee with Clarence Darrow to testify for evolution at the Scopes trial of 1925. When I think that we are enmeshed again in the same struggle for one of the best documented, most compelling and exciting concepts in all of science, I don’t know whether to laugh or cry.

  According to idealized principles of scientific discourse, the arousal of dormant issues should reflect fresh data that give renewed life to abandoned notions. Those outside the current debate may therefore be excused for suspecting that creationists have come up with something new, or that evolutionists have generated some serious internal trouble. But nothing has changed; the creationists have presented not a single new fact or argument. Darrow and Bryan were at least more entertaining than we lesser antagonists today. The rise of creationism is politics, pure and simple; it represents one issue (and by no means the major concern) of the resurgent evangelical right. Arguments that seemed kooky just a decade ago have reentered the mainstream.

  The basic attack of modern creationists falls apart on two general counts before we even reach the supposed factual details of their assault against evolution. First, they play upon a vernacular misunderstanding of the word “theory” to convey the false impression that we evolutionists are covering up the rotten core of our edifice. Second, they misuse a popular philosophy of science to argue that they are behaving scientifically in attacking evolution. Yet the same philosophy demonstrates that their own belief is not science, and that “scientific creationism” is a meaningless and self-contradictory phrase, an example of what Orwell called “newspeak.”