The Case Against Biological Realism About Race: from Darwin to the Post-Genomic Era
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The Case against Biological Realism about Race: From Darwin to the Post-Genomic Era Kofª N. Maglo University of Cincinnati This paper examines the claim that human variation reºects the existence of biologically real human races. It analyzes various concepts of race, including conceptions of race as a breeding population, continental cluster and ancestral line of descent, or clade. It argues that race functions, in contemporary hu- man population genetics, more like a convenient instrumental concept than bi- ological category for picking out subspeciªc evolutionary kinds. It shows that the rise of genomics most likely provided opponents of the biological reality of human races with at least as much ammunition as that of their counterparts the race realists. The paper also suggests that the roots of the current epistemic landscape of the debate can be traced back to Darwin’s essay on The Descent of Man. [T]he races of man are not sufªciently distinct to inhabit the same country without fusion; and the absence of fusion affords the usual and best test of speciªc distinctiveness. (Charles Darwin [1871] 2004, p. 202) The subspecies is merely a strictly utilitarian classiªcatory device for the pigeonholing of population samples. (Ernst Mayr 1954, p. 87) Introduction Did human evolutionary history lead to a natural division of our species into subspecies, the so-called biological human races? The issue seemed to This paper and the previous one (Maglo 2010) grew out of an earlier version I presented at a roundtable on genetics and race at Harvard University in 2004, at the Annual Meeting of the American College of Epidemiology in Boston in 2004, and also at MIT in 2004 in the Program in Science, Technology, and Society (STS). I thank Philip Kitcher, Lisa Lloyd, Perspectives on Science 2011, vol. 19, no. 4 ©2011 by The Massachusetts Institute of Technology 361 Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/POSC_a_00048 by guest on 01 October 2021 362 The Case against Biological Realism about Race have been beaten to death during the second half of the 20th century. But the situation in the biological sciences changed signiªcantly with the rise of genomic science at the close of the century. The issue of race in science, which most people had deemed passé and obsolete, has now resurfaced in heated disputes among scientists and philosophers. One group of research- ers argues that race has an objective biological reality and is a valid predic- tive tool of genetic and phenotypic variation within our species, while an- other group counters that race is biologically meaningless and a weak predictive factor of human genetic and phenotypic variation. In what follows, I show that, despite the relative momentum gained by biological race realism in recent years, realists still fail to satisfactorily an- swer the enduring objections raised, some originally by Darwin himself, against the biological reality of race. In fact, with the genomic revolution, the “no biological human race” school has grown equally strong, highly empiricist, and very sophisticated. I thus maintain that, based on currently available evidence and methods, classiªcations of humans into races in biol- ogy very likely represent mere instrumental groupings rather than subspe- ciªc evolutionary branches, hereafter called subspeciªc evolutionary kinds.1 That is, unless future scientiªc ªndings suggest otherwise, race may be con- Richard Burian and Quayshawn Spencer for their comments on the earlier version of this paper. In 2003, I started collaboration with scientists at the National Human Genome Center at Howard University. In Summer 2005, Esteban Burchard invited me to his Lab at the University of California, San Francisco (UCSF) where he leads a team of researchers working on asthma in Hispanics. During my stay in Burchard Lab, I was able to meet and interview Troy Duster and Neil Risch at their respective universities. These experiences, among others, motivated me to organize in 2007 a colloquium at the University of Cincinnati on “Race in the Age of Genomic Medicine: The Science and its Applications.” I am grateful to all the participants for their wonderful presentations and discussions. The issue of race in science and medicine, as I gradually came to grasp it, can roughly be sum- marized in the following words of the 19th century bio-medical scientist Claude Bernard ([1865] 1957, p. 39): “When two [biologists] or doctors quarrel, each maintaining his own ideas or theories, in the midst of their contradictory arguments, only one thing is abso- lutely certain: that both theories are insufªcient, and neither of them corresponds to the truth.” Although this statement may not be generally true, it seems to me particularly ap- plicable to the dispute between biological realists and eliminativists over race. Thus I ar- ticulated here an instrumentalist view of race as an alternative to both the realist and the eliminativist interpretations. However, it is in my previous paper, actually a follow-up of this one in the order of conception, that I initiated the discussion of the theoretical and ethical conditions for a possible instrumental use of race in the biomedical sciences. I have therefore chosen to focus in the present paper primarily on the issue about the alleged evo- lutionary divergence of human races. 1. Although I emphasize here human evolutionary history, the reader will soon realize that I do not completely neglect the issue about developmental kinds (See also Maglo 2010). Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/POSC_a_00048 by guest on 01 October 2021 Perspectives on Science 363 sidered merely a convenient problem-solving tool—to be deployed in well- controlled situations with appropriate ethical safety nets—rather than a pri- mary or fundamental category in human population genetics. The paper is an interdisciplinary paper that gathers evidence from his- tory, genomics, and philosophy in order to answer the question of whether or not human races are evolutionary kinds. It starts with the clash between realists, instrumentalists, and eliminativists about race during the period prior to the DNA revolution. It then examines the genomic evidence for and against the existence of biological human races, focusing primarily on the issues of genetic diversity and cladistic ancestral lineage determination within the human species. Finally, the paper explores the philosophical implications of both the historical and the genomic debates over the bio- logical reality of race. In all, it suggests that from Darwin to contempo- rary post-genomic scientists, the case against the existence of biological human races has grown sharper and more robust than recently thought. However, the paper not only places the genomic debate over race in histor- ical and philosophical perspectives, but it also presents, beyond the issue of race, a new view about the objectivity of kinds in biology. I. Historical Roots of the Key Epistemic Trends in the Scientiªc Debate over Race The current scientiªc debate over race appears to oppose two different schools of thought. On one side is the realist school, which posits that race is a valid biological concept and an objective fact of nature. On the other side is the “no biological human race” school, often conºated with a ver- sion of eliminativism which not only denies that the human species reached the level of intra-speciªc differentiations that may qualify as bio- logical races, but also calls for the elimination of the concept of race from science, medicine, and public health policy (See Maglo 2010). His- torically, however, the epistemic landscape of the debate also encompasses alternative frameworks. For instance, Johan Friedrich Blumenbach—a key ªgure in the pre-Darwinian scientiªc investigation of human races—and Charles Darwin himself seemed to subscribe neither to realism nor eliminativism about race. Darwin, for one, entered the debate over race at a time when researchers were still divided about whether humans formed one single species. Even though scholars such as Kant and Blumenbach previously had defended monogenesis, or the notion that all humans de- scended from a common origin, polygenesis—the idea that different hu- man races have different origins—was still rampant. For Darwin, however, “when the principle of evolution is generally accepted, as it surely will be before long, the dispute between the monogenists and the polygenists will die a silent and unobserved death” (Darwin 2004, p. 210). With the tri- Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/POSC_a_00048 by guest on 01 October 2021 364 The Case against Biological Realism about Race umph of Darwin’s theory, the debate indeed shifted from the disunity of the species to whether human races constituted independent evolutionary branching at the subspecies level.2 Still, all along, the then-emerging race concept unsuccessfully confronted objections similar to Darwin’s argu- ments about the lack of sufªcient biological distinctiveness among so- called human races. According to Darwin, the strongest argument in favor of the unity of the species is that human races gradate into each other, indicating thus that there is no evolutionary branching within the species. This lack of sharp natural delineations, he noted, led to the proliferation of human races in science to the extent that there were as many human races as a re- searcher wanted to recognize. The situation, as Darwin put it, “shows that they graduate into each other, and that it is hardly possible to discover clear distinctive characters between them” (2004, p. 203). In current biol- ogy (and since J. S. Huxley), the phenomenon of insensible gradation of traits is referred to as clines, i.e., gradual variations in phenotypes across geographic areas. However, Darwin already made it clear that the gradual distribution of traits among humans cannot be explained simply by popu- lation admixture. In fact, Darwin’s point was that human beings are too similar to be cat- egorized into distinct evolutionary branches.