THE TROUBLE WITH RACE: SCIENCE AND THE PROBLEM OF RACIAL CATEGORIES

I gave a talk last week on ‘Why both sides are wrong in the race debate’ at a conference hosted by the Norwegian Academy of Science and Letters.  For the full argument (not just about the science, but also the history and politics of race) see my book Strange Fruit.

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THE PROBLEM FOR SO-CALLED RACE REALISTS TODAY IS THE VERY OPPOSITE OF that for nineteenth century racial scientists. Then racial scientists ‘knew’ the significance of race but could find no way of defining differences. ‘Race in the present state of things is an abstract conception’, wrote Paul Broca, the leading physical anthropologist of the late nineteenth century, ‘a conception of continuity in discontinuity, of unity in diversity. It is the rehabilitation of a real but directly unobtainable thing.’

Even the staunchest advocates of racial science despaired of establishing race as a real, physical entity. Every ‘scientific’ measure of racial type, from headform to blood group, was shown to be changeable and not exclusive to any one group. As racial scientists searched desperately for more and more trivial manifestations of race, the biologist WJ Solas noted, apparently without a hint of irony, that ‘it is on the degree of curliness or twist in the hair that the most fundamental divisions in the human race are based.’

Today, as numerous genetic studies reveal, we can clearly define differences between populations. But the significance of such differences no longer seems clear. Race only appears to have any validity if we are willing to be deliberately vague as to what constitutes a race, and what racial differences mean.

Any scientific classification must possess three properties. First, there must be consistent and unique principles of classification. So, when biologists order the living world, the rules they use to define humans (Homo sapiens) as a species are the same as the rules they use to define chimpanzees (Pan troglodytes) as a species. Second, the categories must be mutually exclusive. A chimpanzee cannot belong to two distinct species. And third, a classification system must be complete and able to absorb even those entities not yet identified. If we discover a new species we can slot it into the system we use to classify all other known species.

Racial classifications possess none of these properties. Races are difficult to define and there are no objective rules for deciding what constitutes a race or to what race a person belongs. People can belong to many races at the same time. You can be an Icelander, a European and a Caucasian at the same time. Of course, in the classification of the natural world, the same animal can be a chimpanzee, a mammal and a vertebrate. But the species Pan troglodytes, the class Mammalia and the phylum Chordata occupy different levels of the taxonomic hierarchy; each is a distinct classificatory unit. Icelander, European and Caucasian, on the other hand, are all considered by race realists to be the same kind of classificatory unit – a ‘race’.

And, finally, new races are not ‘discovered’ and slotted into the existing classification system; they are ‘created’ by carving up the classification system in a different way. Consider, for instance, the racial categories used in the US census. In 1977, the US government established four racial categories for the census: American Indian or Alaskan Native; Asian or Pacific Islander; Black; and White. Twenty years later the categories were revised by the addition of a fifth race – ‘Native Hawaiian or other Pacific islander’ created by splitting the ‘Asian or Pacific Island’ category into two. This was not because a new race had been discovered, but because social changes required new forms of identity.

In the absence of a scientific classification of race, geneticists and anthropologists are forced to import the racial categories we use in everyday life. But everyday categories are both uncertain and contradictory. When we ordinarily talk about human differences, we are often vague about the terms we use. We may talk interchangeably about races, cultures, ethnic groups, or populations. We generally refer to whites or Europeans rather than Caucasians even though many Caucasians are neither white nor European. On the other hand, we use the term blacks and Africans interchangeably, even though there are many blacks who are not African.

All this may not matter if we are having a casual conversation. It does matter if we want to use race as a scientific category. What is striking about scientific papers which deploy racial categories is the contrast between the tightness and technical quality of the language when the authors are discussing genes, diseases and physiological processes and the looseness of the language about racial differences.

Take, for instance, a much-quoted paper in the New England Journal of Medicine that made the case for ‘The importance of race and ethnic background in biomedical research and clinical practice’. Published in 2003, the paper tried to demonstrate the ways in which genes responsible for disease vary across races:

Factor V Leiden, a genetic variant that confers an increased risk of venous thromboembolic disease, is present in about 5 per cent of white people. In contrast, this variant is rarely found in East Asians and Africans… Susceptibility to Crohn’s disease is associated with three polymorphic genetic variation in the CARD 15 gene in whites; none of these genetic variants were found in Japanese patients with Crohn’s disease. Another important gene that affects a complex trait is CCR5 – a receptor used by the human immunodeficiency virus (HIV) to enter cells. As many as 25 per cent of white people (especially in northern Europe) are heterozygous for the CCR5-delta32 variant, which is protective against HIV infection and progression, whereas this variant is virtually absent in other groups, thus suggesting racial and ethnic differences in protection against HIV…

NAT2 [is] an enzyme involved in the detoxification of many carcinogens and the metabolism of many commonly used drugs. Genetic variants of NAT2 result in two phenotypes, slow and rapid acetylators. Population-based studies of NAT2 and its metabolites have shown that the slow acetylator phenotype ranges in frequency from approximately 14 per cent among East Asians to 34 per cent among black Americans to 54 per cent among whites… One of the best known examples of a gene that affects a complex disease is APOE. A patient harboring a variant of this gene, APOE e4 has a substantially increased risk of Alzheimer’s risk. APOE e4 is relatively common and is seen in all racial and ethnic groups, albeit at different frequencies, ranging from 9 per cent in Japanese populations to 14 per cent in white populations to 19 per cent in black American populations.

What is striking about this passage is the contrast between the tightness and technical quality of the language when the authors are discussing genes, diseases and physiological process and the looseness of the language about racial differences. The paper specifies the genes – or rather the alleles – exactly: CARD15; CCR5-delta32; APOE e4. No geneticist could confuse one with another. Similarly descriptions of diseases (venous thromboembolic disease, Crohn’s disease), explanations of the consequence of allelic variation (‘Genetic variants of NAT2 results in two phenotypes, slow and rapid acetylators’) and physiological illustrations (‘CCR5 – a receptor used by the human immunodeficiency virus (HIV) to enter cells’) are all specific and all make use of technical language.

Descriptions of population differences, on the other hand, are entirely non-technical and often vague and confusing. Among descriptions used for population groups are ‘whites’, ‘white people’, ‘white people (especially in northern Europe)’, ‘white populations’, ‘East Asians’, ‘Japanese’, ‘Japanese populations’, ‘Africans’, ‘black Americans’, and ‘black American populations’. These are not scientific categories but the language of the saloon bar translated into a scientific idiom.

The categories used in racial studies are often a horrible mishmash of groups that do not belong with each other. So, we are told that whites with Crohn’s disease possess three alleles of the CARD 15 gene none of which are found in Japanese patients. Whites, a group defined by skin colour, are compared to the Japanese, a national group defined by geographic origin. The slow acetylator phenotype that results from a particular variant of the NAT2 gene ‘ranges in frequency from 14 per cent among East Asians to 34 per cent among black Americans to 54 per cent among whites’. The three groups being compared here are a Continental group (East Asian), an admixed group that reveals both African and Caucasian ancestry but is socially defined as ‘black’ (black Americans) and a group with a particular phenotype (whites). These very different categories are treated as equivalent groups.

Imagine a zoologist studying a particular behaviour, say hunting. And imagine this zoologist comparing the hunting behaviour of dogs, reptiles and hairy animals. The study would yield no useful information because the comparison groups are not equivalent. Dogs are a particular species of the class Mammalia; some dog breeds are hunters, other are not. Reptiles form a class taxonomically equivalent to mammals comprising many species. ‘Hairy’ is a description of physical appearance that applies to some dogs, but to no reptiles. Most people would agree that comparing the behaviour of dogs, reptiles and hairy animals would not be particularly useful because they are such different kinds of categories. The same is true of comparisons of diseases between East Asians, white people and black Americans.

Even social scientists, who are generally forced to use more ambiguous concepts than those used by natural scientists, would balk at these kinds of comparisons. If an economist compared productivity rates among whites, black Americans and East Asians, it is unlikely that any reputable journal would publish the study. Nor if a sociologist compared attitudes to crime among ‘white people (especially from northern Europe)’ and ‘other racial groups’. Yet, such comparisons are common in genetic studies of populations differences – studies that one expect to have a stricter methodology than econometric or sociological surveys. Even what appear to be equivalent kinds of groups in racial studies may not be so. It is impossible to know, for instance, whether ‘whites’, ‘white people’ and ‘white populations’ refer to the same population group; ‘white people (especially in northern Europe)’ clearly does not. Do ‘East Asians’, ‘Japanese’, ‘Japanese populations’ refer to equivalent populations? It is difficult to know. No wonder that one survey of medical papers concluded that ‘terms used for race are seldom defined and race is frequently employed in a routine and uncritical manner to represent ill-defined social and cultural factors.’

The character of race in scientific research is ambiguous because race is a social category but one which can have biological consequences. There is no such thing as a ‘natural’ human population. Migration; intermarriage; war and conquest; forced assimilation; voluntary embrace of new or multiple identities whether religious, cultural, national, ethnic or racial; any number of social, economic, religious, and other barriers to interaction (and hence to reproduction); social rules for defining populations such as the ‘one drop rule’ in America – these and many social other factors impact upon the character of a group and transform its genetic profile. That is why racial categories are so difficult define scientifically.

There is no such thing as a ‘natural’ human population. Yet, many of the ways in which we customarily group people socially – by race, ethnicity, nationality, religious affiliation, geographic locality and so on – are not arbitrary from a biological point of view. Members of such groups often show greater biologically relatedness than two randomly chosen individuals. Such groups have often been ghettoized by a coercive external authority, or have chosen to self-segregate from other groups. Hence they are inbred to a certain degree and can act as surrogates, however imperfectly, for biological relatedness Categories such as ‘African American’, ‘people of Asian descent’ and ‘Ashkenazi Jew’ can be important in medical research not because they are natural races but because they are social representations of certain aspects of genetic variation. They can become means of addressing questions about human genetic differences and human genetic commonalities.

This is why race can sometimes be what the psychiatrist Sally Satel calls a ‘Poor man’s clue’ in medicine: not because races are natural divisions of humankind but because investigating socially defined populations can provide a practical means of dividing humans into groups that show different degrees of biological relatedness. But it is a rough and ready process because there exists only a rough and ready relationship between social groups and natural populations. How rough and how ready depends on the particular group and the particular question we are asking. As we saw with sickle cell anaemia, the ways in which society customarily divides populations may not be the most useful in medical research. Race and ethnicity can be surrogates for biological relatedness, in other words, but not necessarily good ones. ‘Deciphering the relationships that may exist between social classifications and biological categories’, the anthropologists Morris Foster and Richard Sharp point out, ‘is not a simple matter’:

The biological significance that a social distinction may have for one purpose can dissolve when those same social categories are used to answer other biological questions. Thus, it may be appropriate to use social categories as a proxy for biological relatedness (or unrelatedness) in some circumstances but not in others.

An individual can have a number of social identities some of which may be important to the research at hand, and some of which are irrelevant. An individual donating DNA might be simultaneously a resident of a particular Indian village in Arizona, a member of the Hopi tribe, a descendant of a Laguna tribal family, a Native American, and someone of Spanish ancestry, as well as an American citizen. Each of these identities, Morris and Foster observe, tells a different social story about the individual and leads to a different scientific perspective on genetic variation. Researchers, in other words, should not assume a priori that the world is naturally divided into a set of ‘races’. Rather, depending on the particular questions they are asking they have to decide which of the socially-given populations are most useful to sample.

The importance occasionally  of group differences in medicine does not reveal the reality of race. Indeed, what we popularly call races are generally least suited to genetic research. That is because the degree of biological relatedness in such racial  groups is barely greater than in a randomly chosen group of people. That is what we mean when we say that just 4 per cent of total human variation exists between races. Races are, however, socially significant and a major way by which we divide up our societies. It may make social sense, therefore, for researchers and clinicians to use race as the basis by which they divide up the population.

Races are not natural divisions of humankind. But socially defined populations provide, nevertheless, a rough and ready means of dividing humans into groups that show different degrees of biological relatedness. The irony is that in order to study human genetic diversity, scientists need socially defined categories of difference. The real question we have to ask ourselves today is not just why people imagine race to be a valid biological category but also why so many believe it to be a valid social category, and why society continues to define people by race.