Species, subspecies, and races

Species, subspecies, and races

David L. Hull

The human species can be looked at from two quite different perspectives. The first perspective is that we are unique–fundamentally different from all other species. How do we protect ourselves from such antigens as viruses? Advocates of the uniqueness thesis would reply, “by our own uniquely human immune system.” This perspective is captured by the constant refrain that one cannot reason from studies done on other organisms to humans. Of course, we do make such inferences–all the time. In fact, by law, new drugs must be tested on other species before they can be tested on human beings. Such laws seem strange if reasoning from other species to human beings is so illicit. The other extreme perspective is that initially we should assume that the human species is a species like any other. We reproduce sexually. Many, many other species also reproduce sexually. We are sexually dioecious. So are lots of other species. Roughly half of human beings are male and half are female, a very common sex ratio. Why? The initial assumption of this second perspective is that the explanations that biologists have devised for sexuality, sexual dimorphism, and sex ratio in other species apply to our species until proven otherwise.

In this paper I adopt the second strategy. Instead of assuming that some characteristics are uniquely human and working out from there to those characteristics that we share with at least some other organisms, I assume that the character under study is commonplace and work my way in toward the few characteristics that are uniquely human. I employ the second strategy to counteract what I see as an extreme prejudice toward humans being unique. Yes, we are unique. All species are. “But we are uniquely human.” Yes, and aardvarks are uniquely aardvarkian. “But our unique characteristics allow us to transcend the limits set for all other creatures.” Maybe so, but so many people spend so much time studying those characteristics that make us uniquely human, it can’t hurt to have a few study those characteristics that we share with other organisms. For example, at Northwestern University, twenty-five of the thirty-three departments included in the College of Arts and Sciences are devoted entirely to studying a single species–Homo sapiens–and my own department is among this majority.

I am not objecting to the skewed distribution of our interests. We find our own species more interesting than all the rest of the universe combined. So be it. But I would like to plead for an occasional introduction of the opposite perspective. Once in a while, let’s tear ourselves away from the intense interest we have in those things uniquely human to view our species from a more inclusive perspective. From past experience, this plea will raise howls of protest from my colleagues in the humanities, but that cannot helped. In this paper, I present a brief overview of biological species as such and then move down to the level of subspecies. Systematists divide all organisms into species. They are required to do so by codes of botanical and zoological nomenclature. Systematists also, quite commonly, subdivide species into subspecies. If such subdivisions are legitimate at least in principle in all other species, why not ours? One response is, of course, that we are unique, but setting such a knee-jerk response to one side, perhaps we can learn something about human races by looking at what they may or may not have in common with subdivisions in other species. At the risk of spoiling any surprises that this paper might have, let me note that racists will not like what they find in the biological literature. If subspecies in human beings are anything like subspecies in other species, then racist beliefs will be difficult to support because such races really do not exist (see also Gould, 1977).

The Need to Classify

Everyone now acknowledges that classifying is one of the first and most basic things that people do. Without classification, we would have no language, perhaps not even thought. A great range of opinions exist, however, with respect to the character of such classifications. At one extreme, monists insist that eventually one and only one way of classifying our experience will be discovered that is optimal for all purposes and from all perspectives. Extreme pluralists, to the contrary, maintain that people can and do classify any way that they please, and no one way of classifying is preferable to any other way. Most people, however, find themselves uncomfortably somewhere in the middle. The same set of entities can usually be classed legitimately in more than one way, but the number of these ways is not large, and some of them serve certain purposes better than do others. In addition, some purposes are more important than others.

People are inveterate classifiers. We have a very strong urge to know names, and once we know the name of the group to which a particular entity belongs, we seem at least partially satisfied. Several years ago I found myself touring Scotland with two elderly relatives. Every few minutes one of them would ask me the name of some local plant. Of course, I did not know the names of these plants, but eventually, in self-defense, I began making up names. “Oh, that’s Queen Alice’s Lace. That’s Redundant Butternut.” I felt a bit guilty, but at least my relatives were happy. Ordinary people through the eons have coined names for local plants and animals. The trouble is that these names vary in a chaotic fashion from place to place and from time to time. A crayfish in one valley might be called a crawdaddy in another, and so on. At other times, this same creature might be designated by a variety of other terms. Ordinary languages are exceedingly complex and variable. Is Italian parsley really parsley (for more, see Dupre, 1993)?

Early in Western history, a professional group arose whose duty it was to bring order to this chaos–biological systematists or taxonomists. They took it upon themselves to classify all living creatures in a single, stable system. To this day, international congresses are convened every few years to update this system and to resolve conflicts. For local people talking to local people, ordinary classifications are good enough, but if you want to talk to people who live outside your restricted language community, or if you want to order plants for your garden from an international distributor, you had best use the formal system developed over the centuries by professional systematists. And for scientists, a single, relatively stable formalized system of nomenclature is absolutely necessary.

Many different schools of language-oriented academics (it is impossible to find a more determinate name for these heterogeneous groups) insist that all sorts of deleterious effects follow from how people classify the world in which we live. Because most (if not all) societies have been sexist, buried in language are all sorts of sexist presuppositions that frustrate attempts to make societies less sexist. Technically, the terms bachelor and spinster are symmetrical, but they certainly differ in their connotations. Because presuppositions such as these are built into both our societies and our languages, they are difficult to ferret out. For example, I could not understand why a student objected to my referring to the New Testament. What had I done wrong this time? I know that “Oriental” and “colored people” are racist while “Asian” and “people of color” are not, but what is wrong with the “New Testament”? This appellation is unacceptable because it implies that the New Testament supplements and supersedes the Old Testament, a belief not shared by Jews.

The same sorts of people who want to sanitize language also object vehemently to stereotyping, especially if the groups in question are subgroups of human beings. Supposedly, Scots are tight with money, Jews drive a hard bargain, while lots of other subgroups are not very good with money at all. That is why they remain poor. Such observations are interpreted as being universal: all Scots are tight with money. On a more charitable reading, all that is being claimed is that, on the average, Scots are tighter with money than are the English, Irish, and so on. However, critics object even to such weaker claims. Any attempt whatsoever to delineate subgroups of people is a sure sign of racism, and races exist only in the minds of racists. Of course, such claims can be interpreted as being merely an instance of a more general view of language–that all classes exist only in the minds of classifiers. As such, it implies nothing special about purported races of human beings.

However, when it comes to the human species at large, the very people who object to stereotyping subgroups of human beings insist on stereotyping the human species itself. According to one prevalent view in the humanities, all human beings are essentially the same, a few deviants notwithstanding. This view is especially prevalent among philosophers. The justification for treating the human species so essentialistically is that we must all be the same if we are all to have the same rights (Rachel, 1990). Certainly, life would be much easier if all human beings were essentially the same, but if evolutionary biology has anything to teach us about the human species, it is that we, like so many other species, are extremely variable. The problem then becomes finding a way for all people to have rights even if we are not all essentially the same. Contrary to the essentialism of the received view, even deviants might well have rights.

Just as one faction of academics is prone to call those who acknowledge subgroups of human beings racists, animal rightists object to the essentialist view of human beings as being “speciesist,” as if human beings are special (Singer, 1975). The situation in the humanities is currently hopeless with respect to these and other views. Factionalism and the accompanying ill will are rife. Anyone who doubts such claims can test them by getting elected to the promotion and tenure committee in his or her university. Postmodernists, deconstructionists, social constructionists, evil positivists, and many other groups populate the academic scene. Even the most inveterate essentialist would have a very hard time treating academics essentialistically. Because of this heterogeneity, no blanket statements can be made with respect to any of these groups, subgroups, and overlapping groups except that they are extremely heterogeneous, no matter how they are classified–exactly the message of this paper for species and subspecies. (At this point, I must warn the reader that quite a few of the academic groups alluded to above use the term essentialism to mean roughly the same thing as philosophers have traditionally meant by the term realism.)

Stereotyping and Essentialism

I do not know how much ordinary language can be sanitized or what social good such purification actually accomplishes, but I do think that pointing out the presuppositions of particular languages is worthwhile–especially more formal languages such as the one constructed by systematists. Sometimes the biases are patent. One of the earliest distinctions in the classification of plants and animals was between vertebrates and invertebrates. Vertebrates could be defined in terms of the prevalence of a few traits, such as possession of a vertebral column, but the invertebrates are a hodgepodge of organisms with nothing in common other than not being part of Vertebrata. For a long time, Vermes (“worms”) formed one of these wastebasket groupings. Early classifications were also extremely anthropocentric. The first distinction in many early classifications was between human beings and everything else. Vestiges of this way of classifying remain in the habit of distinguishing between human beings and animals, as if human beings are not animals. At least since Carolis Linnaeus in the eighteenth century, human beings have been classed with other animals, albeit usually at the “head.”

Essentialism is one of the most prevalent assumptions of classifications that survives to the present. In this traditional usage, classes are essential if they can be defined in terms of necessary and sufficient conditions. Triangles are three-sided closed figures. Anything that is a triangle must have three sides, and anything that is a three-sided closed figure is necessarily a triangle. Essentialism in this traditional sense requires that ideally all class terms can be defined in this way. Each grouping that is a genuine class must have an essence that can be stipulated in a definition that specifies necessary and sufficient conditions for membership. Either an entity belongs to the group or it does not. The few borderline cases that might on occasion exist can be dismissed as monsters.

However, even the staunchest essentialist recognized that the world of our experience does not always come in such sharply distinguishable kinds. Boundaries in conceptual space are fairly sharp for some groups but very fuzzy for others. For example, human beings can be distinguished from other organisms without much trouble. No genuine borderline cases exist. Even the most human of the primates differ markedly from people. However, the boundaries that circumscribe dogs, wolves, coyotes, foxes, and so on are not so sharp (Morell, 1997). In the face of such gradual variation, essentialists tried several ploys. The most common was to enshrine certain members of a class as being standard, normal instances of the kind while others are discounted as deviations–not variations but deviations. For example, a perch is a typical fish while a Dover sole is a deviation from the norm. Modern Europeans are typical human beings while Australian aborigines are, once again, deviations from this norm. Conceptually, essences and deviations go hand in hand. Without norms, the issues of deviations from these norms would never arise.

Early in the history of systematics, this way of viewing living creatures was enshrined in the type-specimen method. For each species, a single specimen was designated as the type specimen and squirreled away in a museum drawer for later use, just as the standard meter bar in Paris serves as a standard for the measurement of space. If you have any doubts about the length of your meter stick, travel to Paris and check. Similarly, if you are not sure about a particular specimen in hand, make the hike to the natural history museum that possesses the type specimen and see. So the story goes, Carolus Linnaeus was chosen as the type specimen for Homo sapiens in order to honor the “father” of biological classification. Whether or not this story is apocryphal, it can serve as an object lesson. In what sense is a relatively short, blue-eyed, blonde, male Swede in any sense a typical human being?

All of the preceding has concerned the distribution of traits. With the acceptance of evolution, descent took priority to the distribution of traits. Present-day systematists still study character distributions, but these characters must now be evolutionary homologies and the goal is to use these characters to infer phylogeny. Even though this alteration in the goals of systematics brought order to some of the complexities involved in biological classification, it introduced new problems of its own. For example, sometimes a species as such will change gradually through time so that no sharp line can be drawn to subdivide this gradually evolving lineage. Any subdivision produces a horde of “deviants” clustered on either side of the divide. In addition, sometimes a single species will split very gradually through time to form two new species. Again, the organisms at this fork are reduced to being borderline cases in classification. Too often, it seems, the deviants outnumber the normal cases.

The preceding conclusions have been reached only after considerable labor by numerous systematists and evolutionary biologists. One way of classifying organisms is by the covariation of their observable traits with no regard to their evolution. Organisms do seem to exist in reasonably discrete groups. If only enough characters are used and clustered in some objective way, then a single classification of living creatures can be produced that is equally useful for all biologists. A school of taxonomy arose over three decades ago with the goal of producing a general-purpose classification that reflects one and only one property of living creatures–their overall similarity (Sokal and Sneath, 1963). As plausible as this goal may seem, the assumptions upon which it was built disappeared under analysis. Sometimes increasing the numbers of characters used results in an asymptotic approach to one classification; sometimes not. It all depends on which clustering techniques you use. Instead of a single classification gradually emerging, the number of alternative classifications increased. The end result is that some advocates of this school of taxonomy concluded that no such thing as a general purpose classification exists. All that systematists can do is to produce numerous alternative, special purpose classifications (for the earliest reluctant advocates of this conclusion, see Ehrlich and Ehrlich [1967], the husband and wife team known best for their championing of conservation and population control).

In part because of all the problems that advocates of the preceding position in taxonomy uncovered, most systematists today have returned to the earlier goal of biological classification–to reflect phylogenetic descent–but they have returned to it with the conviction that phylogenetic classifications can be made more rigorous and objective if they limit themselves to one and only one character of phylogeny to reflect in their classifications–order of branching. They also insist that taxonomists cannot use all characteristics in constructing their classifications. Instead, they must search for perfectly nested characteristics (evolutionary homologies) to define their perfectly nested monophyletic taxa. The net result is a grouping of higher taxa that seem to fulfill the requirements of Aristotelian essentialist classifications. All the heterogeneity that early systematists had uncovered resulted from their failure to distinguish between true characters (evolutionary homologies) and all the noise introduced by individuating characters inappropriately. However, this conclusion follows only for higher taxa (genera, families, and so on), and only if common ancestors are excluded from classifications and no hybridism occurs anywhere in the phylogenetic tree. This line of reasoning implies nothing about species and subspecies–the topic of this paper–because the principles of phylogenetic taxonomy as first set out by Hennig (1950) do not apply to species and subspecies, only to higher taxa (Wiley, 1981); see also Donoghue (1985) on “metaspecies.”

So much for professional systematists. How about ordinary people? As Atran (1990) has argued at great length, people of all sorts and in a wide variety of circumstances classify plants and animals essentialistically. If genes have anything to do with our psychological make-up, stereotyping has to be at the head of this list. Either we are born with the tendency to stereotype or else we soon are inculcated with this tendency no matter what society we live in. At this juncture, I must mention that I am using the term stereotyping in the morally neutral sense found in standard dictionaries. Increasingly ordinary people seem to be using this term in a morally committed sense. Stereotyping counts as stereotyping only when it is bad. Until this usage finds its way into standard, academic English, I will continue to use the old-fashioned, morally neutral sense.

If Atran (1990) is right, we are especially prone to conceptualize organisms in terms of essences. The compulsion to see the nonliving world in terms of essences is somewhat less powerful. Even so, lead, gold, and water are commonly conceptualized as if they could be characterized in terms of essential characteristics. However, as science has progressed, the justification for these two sorts of stereotyping has changed. Isotopes and isomers notwithstanding, the physical elements are characterized by physicists in terms of their atomic numbers, and that is it. Hydrogen atoms have an atomic number of one, helium has two, and so on. Just the opposite conclusion has been reached by biological systematists with respect to species. If species are taken to be the things that evolve through the evolutionary process, then they cannot be defined essentialistically. In fact, it follows that technically they cannot be defined at all, but this line of argument goes far beyond the scope of this paper (Hull, 1976).

Hence, one of the strongest arguments against stereotyping and essentialism with respect to species comes from biological systematics. If Atran is right, people of all sorts are addicted to stereotyping species of plants and animals. If so, curing them of such a mistaken and possibly immoral view will be not only quite difficult but also never ending. Every generation will have to be convinced all over again. However, the nature of biological species is a moral issue only for those people who ground human rights in human nature. When we turn our attention to subspecies, numerous people find the nature of races, at least human races, morally relevant. I do not propose to argue that what systematists say about subspecies can either justify or refute racism. Moral issues are not resolved by science, but at least scientists can tell us what the lay of the land is. We then can make up our minds on moral issues in the presence of as much knowledge as we can get about the facts of the matter. Moral commandments that require that people should do or not do what is empirically impossible for people to do are clearly deficient. “Thou shall run a two-minute mile” makes just about as much sense as “Thou shall not run a two minute mile.”

At this point, it might be useful to attempt to explain how systematists view species. Numerous different definitions have been provided for the species category. Mayden (1997) lists twenty-two of the most prominent of these definitions. One of the most influential definitions treats species as groups of organisms that either mate successfully with each other or would do so if they had access to each other. On this definition, asexual organisms do not form species. Since nearly all organisms reproduced asexually during the first half of life on Earth, no species existed during this time. In the face of such serious problems, some systematists throw up their hands and declare that species are just arbitrary assemblages that have no real existence in nature. Others, equally aware of all these difficulties insist that, if any groups of organisms can be said to exist in nature, species can. Their continued effort to formulate more adequate definitions of the species category attest to this belief. At the very least, species are the things that evolve. Periodically, evolutionists have argued that species them selves can actually function in the evolutionary process and not just result from it. If species selection occurs, then species may or may not be “real,” but they are in either case very important. However, the existence of species selection remains a highly contentious issue in evolutionary biology. In sum, systematists find species as the things that evolve to be the most “real” groups of organisms around, even if they are not real enough for some to count them as being really real.

Subspecies and Racism

How about subspecies? Darwin (1859, p. 52) thought that the sort of subspecific groupings recognized by systematists might function as incipient species in the evolutionary process. They are species in the making. If so, then considerable effort in recognizing subspecies would be worthwhile. At one time, Homo sapiens might have formed a homogenous whole, but as time has gone by and our ancestors scattered across the globe, our species began to fragment, and if this fragmentation were to continue for several hundred thousand years or so, perhaps one or more of these fragments might eventually evolve into a new species. To the contrary, evolutionary biologists are now in wide agreement that subspecies are not incipient species. Much more localized subspecific groups are actually the source of new species. In addition, the fragmenting of the human species is rapidly being undone as people wander over the face of the earth, mating as they go. The human species is highly heterogeneous and is likely to remain so in the foreseeable future, but clumps of such differences are being dissipated by the amount of intermarriage that is going on. Miscegenation does not decrease the heterogeneity of the human species at a locus-by-locus perspective. No loci let alone alleles are lost in the process. All that is modified is patterns of clumping of particular loci (Cavalli-Sforza, Menozzi, and Piazza, 1994).

Assuming that subspecies play no significant role in the evolutionary process, might not they still be worth recognizing? The most important journal in systematics over the past third of a century is Systematic Zoology. During its early years, the first controversy to be aired in that journal was the subspecies problem, beginning with a paper by E. O. Wilson (of sociobiology fame) and W. L. Browne, Jr. (1953). Given the number of times that Wilson has been called a racist and worse, one would expect him to champion subspecies as important groupings in nature. To the contrary, he and Brown (1953, p. 108) conclude that the subspecies has “outlived its usefulness.” In particular, the specification of a certain percentage of characters that organisms must have in common to count as a subspecies (for example, the 75 percent rule) shows how artificial and arbitrary subspecies actually are (Edwards, 1954, p. 4). Nearly all of the authors of the eighteen papers that appeared in the pages of Systematic Zoology for the fifteen years that followed agreed with Wilson and Brown that subspecies should not be a formally recognized category in systematics. Workers can subdivide their species in as many ways as they choose–into geographic races, demes, varieties, you name it–but these subgroupings should not be named and included as part of formal classifications. They are too ephemeral and variable to warrant official recognition.

Those systematists who have high standards for claiming that species exist should be expected to reject subspecies–and they do. Subspecies exhibit all the problems that species exhibit–and more. But even those systematists who are willing to recognize that species exist throw in the towel when it comes to subspecies. In sexual species, reproductive isolation, in the best of circumstances, can be used to distinguish between species, but nothing like reproductive isolation exists for subspecific groupings. If character covariation is used, it ranges from very little to very much, the 75 percent rule being a compromise. Biogeographic distribution is somewhat more interesting and significant. Anthropologists attempt to trace the wanderings of various groups of people from land mass to land mass. The story that they tell is as complicated as it is fascinating. As in the case of all historical reconstructions, large parts of the story are extremely speculative. Even so, groups of people have formed in isolation from other people for fairly long periods of time and have even moved as a group from one area of the earth to another, sometimes expanding to overrun large areas, sometimes being reduced to relic populations. Just about anything that can happen, did happen (Cavalli-Sforza, Menozzi, and Piazza, 1994).

Well, how about races? Ordinary people in first-world countries tend to group people into four or five races that we define in terms of such outward signs as skin color. None too surprisingly, these are the races that racists and antiracists have in mind in their disputes. But these common-sense groupings are not the races recognized by professional anthropologists. They subdivide people into such groups as Negroids, Caucasoids, Mongoloids, Amerindians, Australoids, and Negritoes. Needless to say, at any one time, anthropologists have failed to achieve a consensus on which groupings to recognize, and through the years the number of races recognized by anthropologists as well as their boundaries and distributions have varied considerably. Part of this variation has been due to increased knowledge, but part is also due to the fact that anthropologists are discovering all the problems with respect to Homo sapiens that other systematists have found with respect to species in general. Periodically, some of the groupings produced by professional anthropologists correspond roughly to common sense races, but such correspondences are very rough and extremely short lived. Ordinary people remain contentedly oblivious to all these professional disagreements, and racism is first and foremost a fact about ordinary people reasoning the way that ordinary people reason.

If Atran (1990) is right about our strong predilection to stereotype, especially with respect to living organisms, then one should not be in the least surprised to discover that we do the same for subgroupings in our own species. That such stereotypes have no scientific justification should also come as no surprise. I suspect that various shades of racism can be discovered in scientists who have studied Homo sapiens, but in spite of this racism, those scientists who know most about species and subspecies have reached consensus about races. They are too variable and ephemeral to recognize for other than very localized studies. More importantly, the subdivisions of Homo sapiens that experts recognize do not come close to coinciding with the “races” of ordinary people. Several groups of people who are considered Caucasoids by anthropologists would rouse all the anxiety and hostility in ordinary white racists that blacks do. Their skin is black. They look black. But technically, they are Caucasoids. But such observations are not likely to persuade the members of the admissions committee of an all-white country club.

Conclusion

The purpose of this paper has not been to argue against racial prejudice. It has been to see what we can learn about subdivisions of Homo sapiens if we look at our species as just one more species out of millions. In general, professional systematists do not place much weight on the groupings below the species level. Any one species can be subdivided in too many different ways, and there is really no way that one classification can be shown to be clearly superior to the others. Some people for philosophical reasons argue that all classes are equally arbitrary. Others adopt the more reasonable but difficult position that some classes are more real than others. For them the contrast between species and subspecies is apposite. Any systematist who concludes that species do not exist is committed afortiori that subspecies do not exist either, because they are even more problematic than species. However, those systematists who do acknowledge the reality of species are in a position to extend this status to subspecies. By and large, they do not. Races of human beings have just about as much reality as “Queen Alice’s Lace” or “Redundant Butternut.” Hence, the current state of biological systematics with respect to subspecies does not provide much support to racists. If races do not exist in any significant sense, then it is hard to see how one race can be superior to other races.

However, racists do not need support from science. They are happy to back up their views with science when scientists seem to support them, but they cheerfully ignore science when it works against them. Reference to science is as much window dressing for the real concerns of racists as it is for creation scientists. No doubt certain scientists through the years have published claims about human beings with the explicit purpose of promoting racism. Just as surely other scientists have presented views whose explicit purpose is to count against racism (Wolpoff and Caspari, 1996). Both sorts of scientists have a higher opinion of the effects of scientific disputes on the deep-seated beliefs and fears of my fellow human beings than I have.

References

Atran, S., Cognitive Foundations of Natural History (Cambridge: Cambridge University Press, 1990).

Cavalli-Sforza, L. L., Menozzi, P., and Piazza, A., The History and Geography of Human Genes (Princeton: Princeton University Press, 1994).

Darwin, Charles, On the Origin of Species (London: John Murray, 1859).

Donoghue, M.J., “A Critique of the BSC and Recommendations for a Phylogenetic Alternative,” The Bryologist 83 (August 1985): 172-81.

Dupre, J., The Disorder of Things (Cambridge, Mass.: Harvard University Press, 1993).

Edwards, J. G., “A New Approach to Infraspecific Categories,” Systematic Zoology 3:1 (March 1954): 1-20.

Ehrlich, P. R., and Ehrlich, A. H., “The Phenetic Relationships of the Butterflies,” Systematic Zoology 16:4 (December 1967): 301-27.

Gould, S.J., “Why We Should Not Name Human Beings,” Ever Since Darwin (New York: W. W. Norton, 1977), pp. 231-36.

Hennig, W., Grundzuge einer Theorie der phylogeneticshen Systematik (Berlin: Deutscher Zentralverlag, 1950).

Hull, D. L., “Are Species Really Individuals?” Systematic Zoology 25:2 (June 1976): 174-91.

Mayden, R., “A Hierarchy of Species Concepts: The Denouement in the Saga of the Species Problem,” in M. F. Claridge, H. A. Dawah, and M. R. Wilson, eds., Species: The Units of Biodiversity (London: Chapman Hall, 1997), pp. 381-424.

Morrell, V., “The Origin of Dogs: Running with the Wolves,” Science 276 (June 13, 1997): 1647-48.

Rachel, J., Created from Animals: The Moral Implications of Darwinism (Oxford: Oxford University Press, 1990).

Singer, P. Animal Liberation (New York: Random House, 1975).

Sokal, R. R., and Sneath, P. H. A., The Principles of Numerical Taxonomy (San Francisco: Freeman, 1963).

Wiley, E. O., Phylogenetics: The Principles and Practice of Phylogenetic Systematics (New York: John Wiley, 1981).

Wilson, E. O., and Brown, W. L., Jr., “The Subspecies Concept,” Systematic Zoology 2:2 (September 1953): 97-111.

Wolpoff, M., and Caspari, R., Race and Human Evolution: A Fatal Attraction (New York: Simon and Schuster, 1996).

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