THE POSITIVE (AND FORMAL, OR TAXONOMIC)
ARGUMENT FROM RACIAL DEFINITION
We recognize only one formal category for divisions within species—the subspecies. Races, if formally defined, are therefore subspecies. Subspecies are populations inhabiting a definite geographic subsection of a species’ range and sufficiently distinct in any set of traits for taxonomic recognition. Subspecies differ from all other levels of the taxonomic hierarchy in two crucial ways. First, they are categories of convenience only and need never be designated. Each organism must belong to a species, a genus, a family, and to all higher levels of the hierarchy; but a species need not be formally divided. Subspecies represent a taxonomist’s personal decision about the best way to report geographic variation. Second, the subspecies of any species cannot be distinct and discrete. Since all belong to a single species, their members can, by definition, interbreed. Modern quantitative methods have permitted taxonomists to describe geographic variation more precisely in numerical terms; we need no longer construct names to describe differences that are, by definition, fleeting and changeable. Therefore, the practice of naming subspecies has largely fallen into disfavor, and few taxonomists use the category any more. Human variation exists; the formal designation of races is passé.
Some species are divided into tolerably distinct geographic races. Consider, for example, an immobile species separated on drifting continental blocks. Since these subpopulations never meet, they may evolve substantial differences. We might still choose to name subspecies for such discrete geographic variants. But humans move about and maintain the most notorious habits of extensive interbreeding. We are not well enough divided into distinct geographic groups, and the naming of human subspecies makes little sense.
Our variation displays all the difficulties that make taxonomists shudder (or delight in complexity) and avoid the naming of subspecies. Consider just three points. First, discordance of characters. We might make a reasonable division on skin color, only to discover that blood groups imply different alliances. When so many good characters exhibit such discordant patterns of variation, no valid criterion can be established for unambiguous definition of subspecies. Second, fluidity and gradations. We interbreed wherever we move, breaking down barriers and creating new groups. Shall the Cape Colored, a vigorous people more than two million strong and the offspring of unions between Africans and white settlers (the ancestors, ironically, of the authors of apartheid and its antimiscegenation laws), be designated a new subspecies or simply the living disproof that white and black are very distinct? Third, convergences. Similar characters evolve independently again and again; they confound any attempt to base subspecies on definite traits. Most indigenous tropical people, for example, have evolved dark skin.
The arguments against naming human races are strong, but our variation still exists and could, conceivably, still serve as a basis for invidious comparisons. Therefore, we must add the second and third arguments as well.
THE POSITIVE ARGUMENT FROM RECENCY OF DIVISION
As I argued in the first part of this essay (and need only state in repetition now), the division of humans into modern “racial” groups happened yesterday, in geological terms. This differentiation does not predate the origin of our own species, Homo sapiens, and probably occurred during the last few tens (or at most hundreds) of thousands of years.
THE POSITIVE ARGUMENT FROM GENETIC SEPARATION
Mendel’s work was rediscovered in 1900 and the science of genetics spans our entire century. Yet, until twenty years ago, a fundamental question in evolutionary genetics could not be answered for a curious reason. We were not able to calculate the average amount of genetic difference between organisms because we had devised no method for taking a random sample of genes. In the classical Mendelian analysis of pedigrees, a gene cannot be identified until it varies among individuals. For example, if absolutely every Drosophila in the world had red eyes, we would rightly suspect that some genetic information coded this universal feature, but we would not be able to identify a gene for red eyes by analyzing pedigrees, because all flies would look the same. But as soon as we find a few white-eyed flies, we can mate white with red, trace pedigrees through generations of offspring, and make proper inferences about the genetic basis of eye color.
To measure the average genetic differences among races, we must be able to sample genes at random—and this unbiased selection can’t be done if we can only identify variable genes. Ninety percent of human genes might be held in common by all people, and an analysis confined to varying genes would grossly overestimate the total difference.
In the late 1960s, several geneticists harnessed the common laboratory technique of electrophoresis to solve this old dilemma. Genes code for proteins, and varying proteins may behave differently when subjected in solution to an electric field. Any protein could be sampled, independent of prior knowledge about whether it varied or not. (Electrophoresis can only give us a minimal estimate because some varying proteins may exhibit the same electrical mobility but be different in other ways.) Thus, with electrophoresis we could finally ask the key question: How much genetic difference exists among human races?
The answer, surprising for many people, soon emerged without ambiguity: damned little. Intense studies for more than a decade have detected not a single “race gene”—that is, a gene present in all members of one group and none of another. Frequencies vary, often considerably, among groups, but all human races are much of a muchness. We can measure so much variation among individuals within any race that we encounter very little new variation by adding another race to the sample. In other words, the great preponderance of human variation occurs within groups, not in the differences between them. My colleague Richard Lewontin (see bibliography), who did much of the original electrophoretic work on human variation, puts it dramatically: If, God forbid, the holocaust occurs “and only the Xhosa people of the southern tip of Africa survived, the human species would still retain 80 percent of its genetic variation.”
As long as most scientists accepted the ancient division of races, they expected important genetic differences. But the recent origin of races (second positive argument) affirms the minor genetic differences now measured. Human groups do vary strikingly in a few highly visible characters (skin color, hair form)—and these external differences may fool us into thinking that overall divergence must be great. But we now know that our usual metaphor of superficiality—skin deep—is literally accurate.
In thus completing my précis, I trust that one essential point will not be misconstrued: I am, emphatically, not talking about ethical precepts but about information in our best current assessment. It would be poor logic and worse strategy to hinge a moral or political argument for equal treatment or equal opportunity upon any factual statement about human biology. For if our empirical conclusions need revision—and all facts are tentative in science—then we might be forced to justify prejudice and apartheid (directed, perhaps, against ourselves, since who knows who would turn up on the bottom). I am no ethical philosopher, but I can only view equality of opportunity as inalienable, universal, and unrelated to the biological status of individuals. Our races may vary little in average characters, but our individuals differ greatly—and I cannot imagine a decent world that does not treat the most profoundly retarded person as a full human being in all respects, despite his evident and pervasive limitations.
I am, instead, making a smaller point, but one that tickles my fancy because most people find it surprising. The conclusion is evident, once articulated, but we rarely pose the issue in a manner that lets such a statement emerge. I have called equality among races a contingent fact. So far I have only argued for the fact; what about the contingency? In other words, how might history have been different? Most of us can grasp and accept the equality; few have considered the easy plausibility of alternatives that didn’t happen.
My creationist incubi, in one of their most deliciously ridiculous arguments, ofte
n imagine that they can sweep evolution away in the following unanswerable riposte: “Awright,” they exclaim, “you say that humans evolved from apes, right?” “Right,” I reply. “Awright, if humans evolved from apes, why are apes still around? Answer that one!” If evolution proceeded by this caricature—like a ladder of progress, each rung disappearing as it transforms bodily to the next stage—then I suppose this argument would merit attention. But evolution is a bush, and ancestral groups usually survive after their descendants branch off. Apes come in many shapes and sizes; only one line led to modern humans.
Most of us know about bushes, but we rarely consider the implications. We know that australopithecines were our ancestors and that their bush included several species. But we view them as forebears, and subtly assume that since we are here, they must be gone. It is so indeed, but it ain’t necessarily so. One population of one line of australopithecines became Homo habilis; several others survived. One species, Australopithecus robustus, died less than a million years ago and lived in Africa as a contemporary of H. erectus for a million years. We do not know why A. robustus disappeared. It might well have survived and presented us today with all the ethical dilemmas of a human species truly and markedly inferior in intelligence (with its cranial capacity only one-third our own). Would we have built zoos, established reserves, promoted slavery, committed genocide, or perhaps even practiced kindness? Human equality is a contingent fact of history.
Other plausible scenarios might also have produced marked inequality. Homo sapiens is a young species, its division into races even more recent. This historical context has not provided enough time for the evolution of substantial differences. But many species are millions of years old, and their geographic divisions may be marked and deep. H. sapiens might have evolved along such a scale of time and produced races of great age and large accumulated differences—but we didn’t. Human equality is a contingent fact of history.
A few well-placed mottoes might serve as excellent antidotes against deeply ingrained habits of Western thought that so constrain us because we do not recognize their influence—so long as these mottoes become epitomes of real understanding, not the vulgar distortions that promote “all is relative” as a précis of Einstein.
I have three favorite mottoes, short in statement but long in implication. The first, the epitome of punctuated equilibrium, reminds us that gradual change is not the only reality in evolution: other things count as well; “stasis is data.” The second confutes the bias of progress and affirms that evolution is not an inevitable sequence of ascent: “mammals evolved at the same time as dinosaurs.” The third is the theme of this essay, a fundamental statement about human variation. Say it five times before breakfast tomorrow; more important, understand it as the center of a network of implication: “Human equality is a contingent fact of history.”
13 | The Rule of Five
THE HUMAN MIND DELIGHTS in finding pattern—so much so that we often mistake coincidence or forced analogy for profound meaning. No other habit of thought lies so deeply within the soul of a small creature trying to make sense of a complex world not constructed for it.
Into this Universe, and why not knowing
Nor whence, like water willy-nilly flowing,
as the Rubáiyát says. No other error of reason stands so doggedly in the way of any forthright attempt to understand some of the world’s most essential aspects—the tortuous paths of history, the unpredictability of complex systems, and the lack of causal connection among events superficially similar.
Numerical coincidence is a common path to intellectual perdition in our quest for meaning. We delight in catalogs of disparate items united by the same number, and often feel in our gut that some unity must underlie it all. Our ancestors pondered the mystique of seven—the number of planets (sun, moon, and five visible planets, all circling the earth in Ptolemy’s system), the deadly sins, the seals of Revelations. Five has also been favored, not only for fingers and toes but also for the acts of a proper play according to Horace, the smooth stones that David selected to slay Goliath, the few loaves that Christ used to feed the multitude, the number of Mrs. Bixby’s sons (all of whom, apparently, did not die gloriously on the field of battle, Mr. Lincoln notwithstanding). The owl and pussycat went to sea with all their worldly goods wrapped in a five-pound note (a very large bill—in physical size as well as monetary value—in those Victorian days). What this country needs, and will never have again, is a good five-cent cigar.
In this essay, I shall discuss two taxonomic systems (theories for the classification of organisms) popular in the decades just before Darwin published the Origin of Species. Both assumed reasons other than evolution for the ordering of organisms; both proposed a scheme based on the number five for placing organisms into a hierarchy of groups and subgroups. Both argued that such a simple numerical regularity must record an intrinsic pattern in nature, not a false order imposed by human hope upon a more complex reality. I shall describe these systems and then discuss how evolutionary theory undermined their rationale and permanently changed the science of taxonomy by making such simple numerical schemes inconsistent with a new view of nature. This important change in scientific thought embodies a general message about the character of history and the kinds of order that a world built by history, and not by preordained plan, can (and cannot) express.
Louis Agassiz wrote of his teacher, the German embryologist Lorenz Oken:
A master in the art of teaching, he exercised an almost irresistible influence over his students. Constructing the universe out of his own brain…classifying the animals as if by magic, in accordance with an analogy based on the dismembered body of man, it seemed to us who listened that the slow laborious process of accumulating precise detailed knowledge could only be the work of drones, while a generous, commanding spirit might build the world out of its own powerful imagination.
Oken was a fine descriptive anatomist; his treatises on the embryology of the pig and dog, written in 1806, are classics of meticulous care. But Oken was also a leader in the popular early nineteenth-century school of Naturphilosophie—an intellectual movement based on the romantic vision that simple laws of dynamic motion ruled nature and that great intellects might apprehend these laws by a kind of creative intuition. Oken’s major contribution to this movement, his Lehrbuch der Naturphilosophie (1809–1811), is a list, close to 4,000 items long, taking all knowledge for its province and full of oracular pronouncements about nearly everything, from why the earth is a crystal (with mountain ranges as its edges) to why Kriegskunst (the art of war) is the noblest of human endeavors.
Oken, though widely respected in his day (even by his intellectual enemies), has suffered the fate of modern citation largely for laughs about the bad old past versus the bright present. Admittedly, his oracular style of pronouncement invites ridicule by modern standards. What else can one make of Oken’s paean to zero: “The whole of mathematics emerges out of zero, so must everything…have emerged from the eternal or nothing of nature…. There is no other science than that which treats of nothing.” Or his claim that all “lower” animals are merely incomplete humans: “The animal kingdom is only a dismemberment of the highest animal, that is, of Man.”
When divorced from Oken’s own context, these statements lose all meaning, and we can only laugh at their disembodied style. When properly situated, they at least make sense (though we may judge them incorrect today), and we may attribute Oken’s peculiar style to differences in taste and custom, not to stupidity or irrelevance.
The context for most of his peculiar pronouncements—the primacy of zero, animals as aborted humans, taxonomy by fives—lies in the primary doctrine of Naturphilosophie: the idea of a single, progressive developmental tendency in nature. All natural processes move upward in one direction, starting from primal nothingness (Oken’s zero) and advancing toward human complexity and beyond. (Oken’s view is not evolutionary since each new state begins again in the primal zero and moves one st
ep beyond its predecessor. A higher form does not evolve by direct genealogical descent from a less developed ancestor, as an evolutionary theory would require.) Since all animals can be arranged in a single series of ascending complexity, with humans on top, lower creatures are incomplete humans. (Oken defined each new step in complexity as the addition of an organ; thus, creatures below us on the ladder of progress contain fewer organs and are incomplete.)
The excitement of new theories lies in their power to change contexts, to render irrelevant what once seemed sensible. If we laugh at the past because we judge it anachronistically in the light of present theories, how can we understand these changes of context? And how can we retain proper humility toward our own favored theories and the probability of their own future lapse into insignificance? Honest intellectual passions always merit respect.
Evolutionary theory was the greatest context changer in the history of biology. Theodosius Dobzhansky wrote in a famous statement that nothing in biology makes sense except in the light of evolution. But Oken’s world made sense under a different set of beliefs about how nature worked. Dobzhansky meant, of course, that once we recognize evolution as the basis of organic history, all biology must be reformulated. But if we wish to understand why evolution was such a watershed in the history of ideas, we must comprehend the contexts that it replaced, not view them as imperfect harbingers of evolution. They were different, subtle, brilliant (and wrong), not stupid. We must study such theories as Oken’s classification by fives, and we must learn why evolution destroyed their rationale if we wish to grasp the sweep and power of evolution itself.
Oken’s taxonomy by fives attempts to reconcile two principles, both dear to Naturphilosophie, but superficially in contradiction—first, that animals represent a single series of increasing complexity defined by the successive addition of organs; second, that meaningful analogies permeate nature and that each segment of taxonomy mimics or mirrors all the others (the order of mammals, for example, must repeat in miniature the same scheme that arranges all of nature). But how can nature contain, simultaneously, a single ascending series and a set of repeating cycles?
The Flamingo’s Smile Page 17