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Genetic views on race vary considerably between and within academic disciplines. Many views are complex, and are distinguished by subtle differences. Often the significance of differences between views is related to the use of race in biomedicine. This article compares the major contemporary views on race.

Summary of contemporary views

Race may be viewed as a biological or a social construct

As a biological construct

• The term 'race' is usually used as a synonym for subspecies by biologists, though there is a degree of confusion over the term and both terms have a variety of meanings. There is no consensus definition for either subspecies or "race" in biology. Some biologists do not accept the concept of classification below the species level whatsoever, arguing that subspecific classifications are not biological units and that they are subjective and arbitrary.
• Taxonomic: "An aggregate of phenotypically similar populations of a species, inhabiting a geographic subdivision of the range of a species, and differing taxonomically from other populations of the species."
• Population: "Races are genetically distinct Mendelian populations. They are neither individuals nor particular genotypes, they consist of individuals who differ genetically among themselves."
• Lineage: "A is a distinct evolutionary lineage within a species. This definition requires that a be genetically differentiated due to barriers to genetic exchange that have persisted for long periods of time; that is, the must have historical continuity in addition to current genetic differentiation."
• The phylogeographic criteria for 'subspecies' were established in the early 1990s.

  members of a subspecies would share a unique, geographic locale, a set of phylogenetically concordant phenotypic characters, and a unique natural history relative to other subdivisions of the species. Although subspecies are not reproductively isolated, they will normally be allopatric and exhibit recognizable phylogenetic partitioning. ... evidence for phylogenetic distinction must normally come from the concordant distributions of multiple, independent genetically based traits.

Background

Time frame of modern human evolution

Mitochondrial DNA from contemporary humans coalescences to a common ancestor living 150,000 years ago (see Mitochondrial Eve). However, nuclear DNA loci have a range of coalescence times, some predating the origin of modern humans or even hominids.

Distribution of genetic variation within/between populations

Size of variation

Since the 1980s it has been known that human genetic variation is low relative to other species, this is usually attributed to the recent origins of our species, and tends to support the recent single-origin hypothesis (or Out of Africa). It has also been shown that most of this small variation is distributed at the individual and local level (about 90-94%), with the remaining 6-10% distributed at the continental (or racial) level. This observation has been used to argue that racial classifications are not valid when within group variation exceeds between group variation.

A. W. F. Edwards claimed in 2003 that such conclusions are incorrect because the argument ignores the possibility that much of the variation that between populations may be hidden in human population structure and not simply in the variation of the individual factors. While it discredits the F_ST statistic as an argument for the non existence of race, the position does not address other arguments regarding the non-existence of human races.

Also, it has been argued that the calculation of within group and between group diversity has violated certain assumptions regarding human genetic variation. Calculation of this variation is known as F_ST and Long and Kittles (2003) have questioned the validity of this reproducible statistic. The first problem is that effective population size is assumed to be equal in the calculation of F_ST, if population sizes vary, then allele relatedness among alleles will also vary. The second problem is that F_ST calculation has assumed that each population is evolutionarily independent. Calculation of F_ST can therefore only be made for the set of populations being observed, and generalisations from specific data sets cannot be applied to the species as a whole.

Long and Kittles tested four models for determining F_ST and concluded that the model used most often for estimating this statistic is the simplest and worst fitting. Their best fit model was still a poor fit for the observed genetic variation, and calculation of F_ST for this model can only be made on a population by population basis. They conclude that African populations have the highest level of genetic diversity, with diversity much reduced in populations outside of Africa. They postulate that if an extra-terrestrial alien life form killed the entire human species, but kept a single population which it preserved, the choice of population to keep would greatly effect the level of diversity represented. If an African population were selected then no diversity would be lost, whereas nearly a third of genetic diversity would be lost if a Papuan New Guinea population were chosen. Indeed within population genetic diversity in African populations has been shown to be greater than between population genetic diversity for Asians and Europeans. They conclude that their findings are consistent with the American Association of Physical Anthropologists 1996 statement on race

that all human populations derive from a common ancestral group, that there is great genetic diversity within all human populations, and that the geographic pattern of variation is complex and presents no major discontinuity.

They also state that none of the race concepts they discuss are compatible with their results.

Genetic variation is structured by geographic origin

Human genetic variation can be used to deduce the geographical origins of an individual's recent ancestors, this is possible because a small proportion of human genetic variation is geographically distributed, with close geographical proximity strongly correlating with genetic similarity.

It has recently been demonstrated in several studies that to a large extent, without prior knowledge of individual origins, the geographic ancestries of individuals can be inferred from genetic markers. In one of the most extensive of these studies to date, considering 1,056 individuals from 52 human populations, with each individual genotyped for 377 autosomal microsatellite markers, we found that individuals could be partitioned into six main genetic clusters, five of which corresponded to Africa, Europe and the part of Asia south and west of the Himalayas, East Asia, Oceania, and the Americas. Some individuals from boundary locations between these regions were inferred to have partial ancestry in the clusters that corresponded to both sides of the boundary. In many cases, subclusters that corresponded to individual populations or to subsets of populations were also identified.

it is not surprising that numerous human population genetic studies have come to the identical conclusion - that genetic differentiation is greatest when defined on a continental basis........the greatest genetic structure that exists in the human population occurs at the racial level.

However, Claudia Travassos and David R. Williams claim that Risch is actually using race to mean continent of origin.

Race is defined by these authors as the person's primary continent of origin based on the evolutionary tree.

Risch et al also state: "The greatest genetic variation occurs within Africans, with variation outside Africa representing either a subset of African diversity or newly arisen variants."

But is the variation by geographic origin distinct enough to count as race

While geographical origin can be inferred from genetics, observed geographically distributed human genetic variation does not amount to the sort of discontinuous distribution that would be expected if the human population were descended from distinct lineages, neither is the variation great enough for human populations to be considered subspecies, the usual biological synonym for race.

In fact, Sierre and Paablo describe the pattern as one of gradients of allele frequencies that extend over the entire world, rather than discrete clusters.

A recent study in which >350 microsatellites were studied in a global sample of humans showed that they could be grouped according to their continental origin, and this was widely interpreted as evidence for a discrete distribution of human genetic diversity. Here, we investigate how study design can influence such conclusions. Our results show that when individuals are sampled homogeneously from around the globe, the pattern seen is one of gradients of allele frequencies that extend over the entire world, rather than discrete clusters. Therefore, there is no reason to assume that major genetic discontinuities exist between different continents or "races.

Leroi points out the arbitrariness of racial lines drawn through the human species

...the groups that emerge are native to Europe, East Asia, Africa, America and Australasia - more or less the major races of anthropology as practiced 100 years ago......Yet there is nothing very fundamental about the concept of the major continental races; they're just the easiest way to divide things up. Study enough genes in enough people and one could sort the world's population into 10, 100, perhaps 1,000 groups, each located somewhere on the map. This has not yet been done with any precision, but it will be. Soon it may be possible to identify your ancestors not merely as African or European, but Ibo or Yoruba, perhaps even Celt or Castilian, or all of the above.

While races of traditional anthropology is not a technical term and definition may vary according to context, according to National Human Genome Center at Howard University, Races of traditional anthropology include Mongoloid, Australoid, Caucasoid, Negroid .

And the National Human Genome Center at Howard University states,

Modern extant humans do not fracture into races (subspecies) based on the modern phylogenetic criteria of molecular systematics." National Human Genome Center, Howard University. Policy paper. .

Risch, in the source quoted above, has even said that the concept of race is intrinsically unscientific

Our evidence for clustering should not be taken as evidence of our support of any particular concept of “biological race.” In general, representations of human genetic diversity are evaluated based on their ability to facilitate further research into such topics as human evolutionary history and the identification of medically important genotypes that vary in frequency across populations. Both clines and clusters are among the constructs that meet this standard of usefulness: for example, clines of allele frequency variation have proven important for inference about the genetic history of Europe, and clusters have been shown to be valuable for avoidance of the false positive associations that result from population structure in genetic association studies. The arguments about the existence or nonexistence of “biological races” in the absence of a specific context are largely orthogonal to the question of scientific utility, and they should not obscure the fact that, ultimately, the primary goals for studies of genetic variation in humans are to make inferences about human evolutionary history, human biology, and the genetic causes of disease. (Rosenberg et al., 2005)

Topical comparisons

Do biologically distinct races exist?

From a biological taxonomic point of view humans all occupy the same subspecific taxon and are designated Homo sapiens sapiens, (Homo sapiens is the binominal species name, the subspecific name also being sapiens). Some scientists argue that common racial classifications are insufficient, inaccurate, or biologically meaningless. The biological meaninglessness of race does not preclude the importance of human genetic diversity as it applies to geographically distributed populations, often "race" is used in a non-biological self defined sense to infer the geographical ancestry of a person "from both an objective and scientific (genetic and epidemiologic) perspective there is great validity in racial/ethnic self-categorizations, both from the research and public policy points of view." It is well known that many alleles vary in frequency across human populations. However from a biological point of view "race" is usually considered a synonym for subspecies, and in turn the definition of a subspecies requires a far greater degree of diversity than is seen in the human global population.

Race is generally used as a synonym for subspecies, which traditionally is a geographically circumscribed, genetically differentiated population. Sometimes traits show independent patterns of geographical variation such that some combination will distinguish most populations from all others. To avoid making "race" the equivalent of a local population, minimal thresholds of differentiation are imposed. Human "races" are below the thresholds used in other species, so valid traditional subspecies do not exist in humans. A "subspecies" can also be defined as a distinct evolutionary lineage within a species. Genetic surveys and the analyses of DNA haplotype trees show that human "races" are not distinct lineages, and that this is not due to recent admixture; human races are not and never were "pure". Instead, human evolution has been and is characterised by many locally differentiated populations coexisting at any given time, but with sufficient genetic contact to make all humanity a single lineage sharing a common evolutionary fate.

Recent work in anthropological genetics suggests that the traditional, historic and socially-constructed ‘racial’ aggregates that have permeated the Western biomedical literature since the 18th century are largely genetic illusions. Important human biological variation exists, but classical races, as the term is used systematically and taxonomically in the natural sciences, appears inapplicable to modern humans.....Our species collective origins are too recent, the extent of gene flow between us is too great, and our current diversity is too evolutionarily superficial to warrant the racial or subspecies level of differentiation among contemporary humans. Human variability does not neatly package itself into separate and discrete categories, as the term race would indicate. In fact, from a scientific point of view, we humans are a single, highly variable, polytypic race—Homo sapiens sapiens. The second ‘sapiens’ is actually the subspecies or race category. What biodiversity exists among modern humans exists taxonomically below the subspecies level.

Even geneticists that support the concept of biological races maintain that subdividing the human population along the lines of continental races is simply the most convinient method.

...race is merely a shorthand that enables us to speak sensibly, though with no great precision, about genetic rather than cultural or political differences....Some critics believe that these ambiguities render the very notion of race worthless. I disagree. The physical topography of our world cannot be accurately described in words. To navigate it, you need a map with elevations, contour lines and reference grids. But it is hard to talk in numbers, and so we give the world's more prominent features—the mountain ranges and plateaus and plains—names. We do so despite the inherent ambiguity of words. The Pennines of northern England are about one-tenth as high and long as the Himalayas, yet both are intelligibly described as mountain ranges.

Some researchers have used the work of Cavalli-Sforza as support for the idea that races are objectively verifiable, however Cavalli-Sforza, himself, has said, "the idea of race in the human species serves no purpose" and that his research is "expected to undermine the popular belief that there are clearly defined races, to contribute to the elimination of racism". He has also said,

The classification into races has proved to be a futile exercise for reasons that were already clear to Darwin. Human races are still extremely unstable entities in the hands of modern taxonomists, who define from 3 to 60 more races. To some extent, this latitude depends on the personal preference of taxonomists, who may choose to be 'lumpers' or 'splitters'. Although there is no doubt that there is only one human species, there are clearly no objective reasons for stopping at any particular level of taxonomic splitting. In fact, the analysis we carry out..for the purposes of evolutionary study shows that the level at which we stop our classification is completely arbitrary." (Cavalli-Sforza, Menozzi, and Piazza, 1994, p. 19).

The following chart by Cavalli-Sforza shows the genetic distance between different groups:

File:DNAtree.gif

File:Fig.2.3.542pop.jpg

Additionally, according to an article published in The Economist, the work of Cavalli-Sforza "challenges the assumption that there are significant genetic differences between human races, and indeed, the idea that 'race' has any useful biological meaning at all." (The Human Genome Survey, 1 July 2000, pg. 11)

Neil Risch, who has published many papers regarding human genetic variation argues that one of the problems with race is definition (though the usual definition is that "race" equates to subspecies) others agree with Risch:

'Race' is not being defined or used consistently; its referents are varied and shift depending on context. The term is often used colloquially to refer to a range of human groupings. Religious, cultural, social, national, ethnic, linguistic, genetic, geographical and anatomical groups have been and sometimes still are called 'races'. In anthropology, the meaning of race became formalized for humans and restricted to units based on biological variation in keeping with general zoological practice8. Classifications were based on somatic traits......'Race' is applied in formal taxonomy to variation below the species level. In traditional approaches, substantively morphologically distinct populations or collections of populations occupying a section of a species range are called subspecies and given a three-part Latin name. In current systematic practice, the designation 'subspecies' is used to indicate an objective degree of microevolutionary divergence.....We argue that the correct use of the term 'race' is the most current taxonomic one, because it has been formalized. 'Race' gains its force from its natural science root. The term denotes 'natural' distinctions and connotes differences not susceptible to change. One is led to ask, therefore, whether everything that is called a 'racial' difference is actually natural. 'Racial' differences carry a different weight than cultural differences. In terms of taxonomic precision and best practice, is it scientifically correct to identify European Americans, Asians and Pacific Islanders, Han Chinese, Hispanics and African Americans of Middle Passage descent as different races? Although individuals may refer to themselves as belonging to a particular 'race', it is doubtful that this has been done with knowledge of, or concern for, zoological taxonomy, because the common use of the term has come from sociopolitical discourse. Individuals learned the 'race' to which they were assigned.

In response to the statement “Genome variation research does not support the existence of human races.” Risch says:

What is your definition of races? If you define it a certain way, maybe that's a valid statement. There is obviously still disagreement.....Scientists always disagree! A lot of the problem is terminology. I'm not even sure what race means, people use it in many different ways.

So Risch seems not to be using the standard biological definition of "race", but rather a socially constructed definition of "race" (see above), and to be applying this to the small level of genetic variation that is geographically distributed. Risch uses the term "race/ethnicity" for his social construct. He goes on to conclude that few biological definitions are precise:

In our own studies, to avoid coming up with our own definition of race, we tend to use the definition others have employed, for example, the US census definition of race. There is also the concept of the major geographical structuring that exists in human populations—continental divisions—which has led to genetic differentiation. But if you expect absolute precision in any of these definitions, you can undermine any definitional system. Any category you come up with is going to be imperfect, but that doesn't preclude you from using it or the fact that it has utility.

We talk about the prejudicial aspect of this. If you demand that kind of accuracy, then one could make the same arguments about sex and age!

You'll like this. In a recent study, when we looked at the correlation between genetic structure versus self-description, we found 99.9% concordance between the two. We actually had a higher discordance rate between self-reported sex and markers on the X chromosome! So you could argue that sex is also a problematic category. And there are differences between sex and gender; self-identification may not be correlated with biology perfectly. And there is sexism. And you can talk about age the same way. A person's chronological age does not correspond perfectly with his biological age for a variety of reasons, both inherited and non-inherited. Perhaps just using someone's actual birth year is not a very good way of measuring age. Does that mean we should throw it out? No. Also, there is ageism—prejudice related to age in our society. A lot of these arguments, which have a political or social aspect to them, can be made about all categories, not just the race/ethnicity one.

Risch is one of the scientists that deem that the genetic variation seen within the human population is of biomedical importance, but not all scientists agree with this position.

Underpinning the medical acceptance of biological race has been the assumption that substantial human genetic variability is at the core of racial group-level human differences. In the United States, the groups of choice, for comparative health status studies are usually identified by such terms as ‘Black’, ‘White’, ‘Latino’ or ‘Hispanic’, and ‘Asian’. Significant within-group variation is often ignored and this inherent variability is now returning to haunt researchers searching for broad racial generalizations. The key questions in using these macroethnic ‘racial’ groups have been (and continue to be): (1) Do these groups represent statistically valid biological categories? And (2) can they be used as reliable shortcuts to making predictions (probability statements) about group disease susceptibilities and health status? The answers to both of these questions are a resounding No.

Footnotes

1. Bindon, Jim. University of Alabama. "Post World War II". 2005. August 28, 2006.
2. Keita et al. (2004)
3. Templeton (1998)
4. Pigliuchi and Kaplan (2003)
5. Keita (1993). p. 425
6. Mayr (1969)
7. Dobzhansky (1970)
8. ^ Templeton (1998)
9. Avise and Ball (1990)
10. O’Brien and Mayr (1991)
11. Miththapala et al. (1996)
12. Bamshad et al. (2004)
13. Lewontin (2005)
14. ^ Long and Kittles (2003)
15. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12879450&dopt=Abstract
16. Rosenberg et al. (2005)
17. ^ Risch et al. (2002)
18. Travassos and Williams (2004)
19. Serre and Pääbö (2004)
20. ^ Leroi, (2005)
21. NATIONAL HUMAN GENOME CENTER, HOWARD UNIVERSITY. Position paper.
22. Smedley and Smedley 2005; Helms et al. 2005;
23. Templeton (1998)
24. ^ Jackson (2004), p. 218.
25. Keita et al. (2004)
26. The Whole Side of It—An Interview with Neil Risch

References

• Avise, J.C., Ball, R.M. 1990. Principles of genealogical concordance in species concepts and biological taxonomy. Oxford Surveys in Evolutionary Biology 7:45-67.
• Bamshad M., Wooding, S., Salisbury, B. A. and Stephens, J. C. (2004). Deconstructing the relationship between genetics and race. Nature Reviews Genetics, Vol 5 pp. 598-605. Retrieved 28 December 2006.
• Collins, F. S. (2004). "What we do and don't know about 'race', 'ethnicity', genetics and health at the dawn of the genome era". Nature Genetics. doi:10.1038/ng1436. {{cite journal}}: Cite has empty unknown parameter: |month= (help)

• Dobzhansky, T. (1970). Genetics of the Evolutionary Process. New York, NY: Columbia University Press.
• Helms, J. E., Jernigan, M. and Mascher, J. (2005). "The Meaning of Race in Psychology and How to Change It: A Methodological Perspective" (PDF). American Psychologist. 60 (1): 27–36. doi:10.1037/0003-066x.60.1.27. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
• Jackson, F. L. C. (2004). Book chapter: Human genetic variation and health: new assessment approaches based on ethnogenetic layering British Medical Bulletin 2004; 69: 215–235 DOI: 10.1093/bmb/ldh012. Retrieved 29 December 2006.
• Keita, S. O. Y. (1993) The subspecies concept in zoology and anthropology, a brief historical review and test of a classification scheme. Journal of Black Studies 23:416-445.
• Keita, S. O. Y., Kittles, R. A., Royal, C. D. M., Bonney, G. E., Furbert-Harris, P., Dunston, D. M., and Rotimi, C. M. (2004). Conceptualizing human variation: Nature Genetics 36, S17 - S20 (2004) doi:10.1038/ng1455
• Lewonin, R. C. (2005). Confusions About Human Races from Race and Genomics, Social Sciences Research Council. Retreived 28 December 2006.
• Leroy, A. M. (2005). A Family Tree in Every Gene. Published: March 14, 2005, The New York Times, p. A23. . Retrieved 08 January 2006.
• Long and Kittles (2003). Human genetic variation and the nonexistence of human races: Human Biology, V. 75, no. 4, pp. 449-471. [PDF. Retrieved 10 January 2007.
• Mayr, E. (1969). Principles of Systematic Zoology. New York, NY: McGraw-Hill.
• Miththapala, S., Seidensticker, J., O’Brien, S.J. 1996. Phylogeographic Subspecies Recognition in Leopards (Panthera pardus): Molecular Genetic Variation. Conservation Biology 10:1115-1132.
• O’Brien, S.J., Mayr, E. 1991. Bureaucratic Mischief: Recognizing Endangered Species and Subspecies. Science. 2 51:1187-1188.
• * Pigliucci, Kaplan On the Concept of Biological Race and Its Applicability to Humans
• Risch, N., Burchard, E., Ziv, E. and Tang, H. (2002). "Categorization of humans in biomedical research: genes, race and disease". Genome Biology. 3 (7): comment2007.2001 - comment2007.2012. {{cite journal}}: Cite has empty unknown parameter: |month= (help)CS1 maint: multiple names: authors list (link)
• Rosenberg1, N. A., Mahajan, s., Ramachandran, S., Zhao, C., Pritchard, J. K., Feldman, M. W. (2005) Clines, Clusters, and the Effect of Study Design on the Inference of Human Population Structure. PLoS Genet 1(6): e70: doi:10.1371/journal.pgen.0010070
• Serre, D and Pääbö, S. (2004) Evidence for Gradients of Human Genetic Diversity Within and Among Continents Genome Research 14:1679-1685, 2004 doi:10.1101/gr.2529604. Retrieved 08 January 2006.
• Smedley, A. and Smedley, B. D. (2005). "Race as Biology Is Fiction, Racism as a Social Problem Is Real: Anthropological and Historical Perspectives on the Social Construction of Race" (PDF). American Psychologist. 60 (1): 16–26. doi:10.1037/0003-066x.60.1.16. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
• Templeton, A.R. (1998). Human races: A genetic and evolutionary perspective. Am. Anthropol. 100, 632–650.Partial access to article. Retrieved 01 January 2007.
• Travassos, C. and Williams, D. R. (2004). The concept and measurement of race and their relationship to public health: a review focused on Brazil and the United States: Cadernos de Saúde Pública v.20 n.3. doi:10.1590/S0102-311X2004000300003

• Articles to be merged from December 2006
• Race