Gould, Human Equality Is a Contingent Fact of History

I have, so far, only presented the negative evidence for my thesis that human equality is a contingent fact of history. I have argued that the old bases for inequality have evaporated. I must now summarize the positive arguments (primarily three in number) and, equally important, explain how easily history might have happened in other ways.

The positive argument from racial definition. In one of the first columns of this series (March 1974), I presented the biological argument against naming races within any species, and within H. sapiens in particular. The argument is technical and taxonomic; it has nothing to do with human particularities or ethical impositions. Its précis follows:

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 taxonomists to recognize them. 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 choose to name subspecies for such discrete geographic variants. But humans move about and have 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 is subject to all the difficulties and discordances that make taxon omists 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 have such discordant patterns of variation, no valid criterion can be found 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 disproof that white and black are very distinct? Third, convergences. Similar characters are independently evolved again and again; they confuse any attempt to base subspecies on definite traits. Most indigenous tropical people, for example, have evolved dark skin.

The arguments against naming human races arc strong, but our variation still exists and could, conceivably, still serve as a basis for invidious comparisons. Therefore, we need 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 is a product of our recent history. It 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 century. Yet, until twenty years ago, perhaps the most important 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 unless 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 it 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 can't be done if we can only identify variable genes. Ninety percent of all 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. Variation among individuals within any race is so great 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, who did much of the original electrophoretic work on human variation, and whose recent book, Human Diversity (Scientific American Library, 1982), may be consulted for the details, 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) squares well with the minor genetic differences now measured. Human groups do vary strikingly in a few highly visible characters (skin color, hair form)--and this may fool us into thinking that overall differences must be great. But