The term
race refers to the concept of dividing people into
populations or
groups on the basis of various sets of characteristics and beliefs about common ancestry.
[AAPA Statement on Biological Aspects of Race America Association of Physical Anthropologists (AAPA)] The most widely used human racial
categories are based on visible
traits (especially
skin color,
facial features and hair texture), and self-identification.
[Bamshad, Michael and Steve E. Olson. Does Race Exist? , ''Scientific American Magazine'' (10 November 2003).]
Conceptions of race, as well as specific ways of
grouping races, vary by culture and over time, and are often
controversial for scientific as well as
social and
political reasons. The controversy ultimately revolves around whether or not races are natural types or socially constructed, and the degree to which observed differences in ability and achievement, categorized on the basis of race, are a product of inherited (i.e. genetic) traits or environmental, social and cultural factors.
Some argue that although "race" is a valid
taxonomic concept in other species, it cannot be applied to humans.
[S O Y Keita, R A Kittles, C D M Royal, G E Bonney, P Furbert-Harris, G M Dunston & C N Rotimi, 2004 "Conceptualizing human variation" in ''Nature Genetics'' 36, S17 - S20 Conceptualizing human variation ] Many scientists have argued that race definitions are imprecise, arbitrary, derived from
custom, have many exceptions, have many gradations, and that the numbers of races delineated vary according to the culture making the racial distinctions; thus they reject the notion that any definition of race pertaining to humans can have taxonomic rigour and validity.
[For example this statement expressing the official viewpoint of the American Anthropological Association at their webpage : "Evidence from the analysis of genetics (e.g., DNA) indicates that most physical variation lies within so-called racial groups. This means that there is greater variation within 'racial' groups than between them."] Today most scientists study human genotypic and phenotypic variation using concepts such as "population" and "
clinal gradation". Many anthropologists contend that while the features on which racial categorizations are made may be based on genetic factors, the idea of race itself, and actual divisions of persons into groups based on selected hereditary features, are
social constructs.
[Daniel A. Segal '''The European': Allegories of Racial Purity '' Anthropology Today, Vol. 7, No. 5 (Oct., 1991), pp. 7-9 doi:10.2307/3032780][Bindon, Jim. University of Alabama. "Post World War II . 2005. August 28, 2006.]
History
Etymology
Not until the
16th century did the word "race" enter into the
English language, from the
French "''race''" - "race, breed, lineage" (which in turn was probably a
loan from the
Italian "''razza''"). Meanings of the term in the 16th century included "wines with a characteristic flavour", "people with common occupation", and "generation". A meaning of "tribe" or "nation" emerged in the
17th century. The modern meaning, "one of the major divisions of mankind", dates to the late
18th century, but it never became exclusive (note the continued use of the expression "the human race"). The ultimate origin of the word is unknown; suggestions include
Arabic ''
ra'is'' meaning "head", but also "beginning" or "origin".
Race in ancient civilizations
Given visually complex social relationships, humans presumably have always observed and speculated about the physical differences among individuals and groups. But different societies have attributed markedly different meanings to these distinctions. For example, the
Ancient Egyptian sacred text called ''
Book of Gates'' identifies four
ethnic categories that are now conventionally labeled "Egyptians", "Asiatics", "Libyans", and "Nubians", but such distinctions tended to
conflate differences as defined by physical features such as skin tone, with
tribal and
national identity.
Classical civilizations from
Rome to
China tended to invest much more importance in
familial or tribal affiliation than with one's physical appearance (Dikötter 1992; Goldenberg 2003).
Ancient Greek and Roman authors also attempted to explain and categorize visible
biological differences among peoples known to them. Such categories often also included fantastical human-like beings that were supposed to exist in far-away lands. Some Roman writers adhered to an
environmental determinism in which
climate could affect the appearance and
character of groups (Isaac 2004). In many ancient civilizations, individuals with widely varying physical appearances became full members of a
society by growing up within that society or by adopting that society's
cultural norms (Snowden 1983; Lewis 1990).
Julian the Apostate was an early observer of racial differences and believed that they were the result of "Providence":
"Come, tell me why it is that the Celts and the Germans are fierce, while the Hellenes and Romans are, generally speaking, inclined to political life and humane, though at the same time unyielding and warlike? Why the Egyptians are more intelligent and more given to crafts, and the Syrians unwarlike and effeminate, but at the same time intelligent, hot-tempered, vain and quick to learn? For if there is anyone who does not discern a reason for these differences among the nations, but rather declaims that all this so befell spontaneously, how, I ask, can he still believe that the universe is administered by a providence?" (
http://www.tertullian.org/fathers/julian_apostate_galileans_1_text.htm).
Medieval models of "race" mixed
Classical ideas with the notion that humanity as a whole was descended from
Shem,
Ham and
Japheth, the three
sons of Noah, producing distinct
Semitic (
Asian),
Hamitic (
African), and
Japhetic (
European) peoples.
Age of Discovery
The word "race", along with many of the ideas now associated with the term, were products of
European imperialism and
colonization during the
age of exploration. (Smedley 1999) As Europeans encountered people from different parts of the
world, they speculated about the physical, social, and cultural differences among various human groups. The rise of the
Atlantic slave trade, which gradually displaced an earlier
trade in
slaves from throughout the world, created a further
incentive to categorize human groups in order to justify the subordination of African slaves. (Meltzer 1993) Drawing on Classical sources and upon their own internal interactions — for example, the hostility between the
English and
Irish was a powerful influence on early thinking about the differences between people (Takaki 1993) — Europeans began to sort themselves and others into groups associated with physical appearance and with deeply ingrained behaviors and capacities. A set of
folk beliefs took hold that linked inherited physical differences between groups to inherited
intellectual,
behavioral, and
moral qualities. (Banton 1977) Although similar ideas can be found in other cultures (Lewis 1990; Dikötter 1992), they appear not to have had as much influence upon their social structures as was found in Europe and the parts of the world colonized by Europeans. However, often brutal conflicts between ethnic groups have existed throughout history and across the world, and
racial prejudice against Africans also exists today in non-colonised countries such as
China and
Japan.
Scientific concepts of race
The first scientific attempts to classify humans by categories of race date from the 17th century, along with the development of European imperialism and colonization around the world. The first post-
Classical published classification of humans into distinct races seems to be
François Bernier's ''Nouvelle division de la terre par les différents espèces ou races qui l'habitent'' ("New division of Earth by the different species or races which inhabit it"), published in 1684.
17th and 18th century
According to philosopher
Michel Foucault, theories of both racial and class conflict can be traced to 17th century political debates about innate differences among ethnicities. In England radicals such as
John Lilburne emphasised conflicts between
Saxon and
Norman peoples. In France
Henri de Boulainvilliers argued that the Germanic
Franks possessed a natural right to leadership, in contrast to descendants of the
Gauls. In the 18th century, the differences among human groups became a focus of scientific investigation (Todorov 1993). Initially, scholars focused on cataloguing and describing "
The Natural Varieties of Mankind," as
Johann Friedrich Blumenbach entitled his 1775 text (which established the five major divisions of humans still reflected in some racial classifications). From the 17th through the 19th centuries, the merging of folk beliefs about group differences with scientific explanations of those differences produced what one scholar has called an "
ideology of race" (Smedley 1999). According to this ideology, races are primordial, natural, enduring and distinct. It was further argued that some groups may be the result of mixture between formerly distinct populations, but that careful study could distinguish the ancestral races that had combined to produce admixed groups.
19th century
The 19th century saw attempts to change race from a taxonomic to a biological concept. In the 19th century a number of
natural scientists wrote on race:
Georges Cuvier,
Charles Darwin,
Alfred Wallace,
Francis Galton,
James Cowles Pritchard,
Louis Agassiz,
Charles Pickering, and
Johann Friedrich Blumenbach. As the science of
anthropology took shape in the 19th century, European and American scientists increasingly sought explanations for the behavioral and cultural differences they attributed to groups (Stanton 1960). For example, using
anthropometrics, invented by Francis Galton and
Alphonse Bertillon, they measured the shapes and sizes of skulls and related the results to group differences in intelligence or other attributes (Lieberman 2001).
These scientists made three claims about race: first, that races are objective, naturally occurring divisions of humanity; second, that there is a strong relationship between biological races and other human phenomena (such as
forms of activity and interpersonal relations and culture, and by extension the relative
material success of cultures), thus biologizing the notion of "race", as Foucault demonstrated in his historical analysis; third, that race is therefore a valid scientific category that can be used to explain and predict individual and group behavior. Races were distinguished by
skin color,
facial type,
cranial profile and size, texture and color of hair. Moreover, races were almost universally considered to reflect group differences in moral character and
intelligence.
The
eugenics movement of the late 19th and early 20th centuries, inspired by
Arthur Gobineau's ''
An Essay on the Inequality of the Human Races'' (1853-1855) and
Vacher de Lapouge's "anthroposociology", asserted as self-evident the biological inferiority of particular groups (Kevles 1985). In many parts of the world, the idea of race became a way of rigidly dividing groups by culture as well as by physical appearances (Hannaford 1996). Campaigns of oppression and
genocide were often motivated by supposed racial differences (Horowitz 2001).
In
Charles Darwin's most controversial book, ''
The Descent of Man'', he made strong suggestions of racial differences and European superiority. In Darwin's view, stronger tribes of humans always replaced weaker tribes. As savage tribes came in conflict with civilized nations, such as England, the less advanced people were destroyed.
[Charles Darwin, ''The Descent of Man'', Chapter 7 - On the Races of Man. Consider, for instance, the following excerpt: "We thus see that many of the wilder races of man are apt to suffer much in health when subjected to changed conditions or habits of life, and not exclusively from being transported to a new climate. Mere alterations in habits, which do not appear injurious in themselves, seem to have this same effect; and in several cases the children are particularly liable to suffer. It has often been said, as Mr. Macnamara remarks, that man can resist with impunity the greatest diversities of climate and other changes; but this is true only of the civilised races."] Nevertheless, he also noted the great difficulty naturalists had in trying to decide how many "races" there actually were (Darwin was himself a
monogenist on the question of race, believing that all humans were of the same species and finding "race" to be a somewhat arbitrary distinction among some groups):
Man has been studied more carefully than any other animal, and yet there is the greatest possible diversity amongst capable judges whether he should be classed as a single species or race, or as two (Virey), as three (Jacquinot), as four (Kant), five (Blumenbach), six (Buffon), seven (Hunter), eight (Agassiz), eleven (Pickering), fifteen (Bory St. Vincent), sixteen (Desmoulins), twenty-two (Morton), sixty (Crawfurd), or as sixty-three, according to Burke. This diversity of judgment does not prove that the races ought not to be ranked as species, but it shews that they graduate into each other, and that it is hardly possible to discover clear distinctive characters between them.
Nevertheless, Darwin wrote that man had "diverged into distinct races, or as they may be more fitly called, sub-species" and that "some of these, such as the Negro and European, are so distinct that, if specimens had been brought to a naturalist without any further information, they would undoubtedly have been considered by him as good and true species." (Darwin, 1871/1874, p. 929)
[Darwin, C. (1871/1874). The Descent of Man, 2nd. Ed., London: John Murray.]
20th- and 21st-Century debates over race
Models of human evolution
In a recent article, Leonard Lieberman and Fatimah Jackson have called attention to the fact that although the concepts of cline, population, and ethnicity, as well as humanitarian and political concerns, have led many scientists away from the notion of race, a recent survey showed that physical anthropologists were evenly divided as to whether race is a valid biological concept. Noting that among physical anthropologists the vast majority of opposition to the race concept comes from population geneticists, any new support for a biological concept of race will likely come from another source, namely, the study of human evolution. They therefore ask what, if any, implications current models of human evolution may have for any biological conception of race.
[Leonard Lieberman and Fatimah Linda C. Jackson (1995) "Race and Three Models of Human Origin" in ''American Anthropologist'' Vol. 97, No. 2, pp. 232-234]
Today, all
humans are classified as belonging to the species ''Homo sapiens sapiens.'' However, this is not the first species of hominids: the first species of genus ''Homo'', ''Homo habilis'' evolved in East Africa at least 2 million years ago, and members of this species populated different parts of Africa in a relatively short time. ''Homo erectus'' evolved more than 1.8 million years ago, and by 1.5 million years ago had spread throughout the Old World. Virtually all physical anthropologists agree that ''Homo sapiens'' evolved out of ''Homo erectus.'' Anthropologists have been divided as to whether ''Homo sapiens'' evolved as one interconnected species from ''H. erectus'' (called the Multiregional Model, or the Regional Continuity Model), or evolved only in East Africa, and then migrated out of Africa and replaced ''H. erectus'' populations throughout the Old World (called the Out of Africa Model or the Complete Replacement Model). Anthropologists continue to debate both possibilities, and the evidence is technically ambiguous as to which model is correct, although most anthropologists currently favor the Out of Africa model.
The multiregional model
Current advocates of the Multiregional model, primarily Milford Wolpof and his associates, have argued that the simultaneous evolution of ''H. sapiens'' in different parts of Europe and Asia would have been possible only if there was a degree of
gene flow between archaic populations.
[Thorne, Alan, and Milford Wolpoff (1992) "The Multiregional Evolution of humans" in ''Scientific American, April 76-93; Smith, Fred and Frank Spencer, eds (1984) ''The Origin of Modern Humans''] Frayer et al. (1993) cite as evidence anatomical continuity in the fossil record in South Central Europe (Smith 1982), East Asia and Australia (Wolpoff 1993) (anatomical affinity is taken to suggest genetic affinity). They argue that very strong genetic similarities among all humans do not prove recent common ancestry, but rather reflect the interconnectedness of human populations around the world, resulting in relatively constant gene flow (Thorne and Wolpoff 1992). They further argue that this model is consistent with clinal patterns of phenotypic variation (Wolpoff 1993). The Multiregional model should not be confused with
Polygenism, which states that ''H. sapiens sapiens'' evolved from ''isolated and separate'' groups of ''H. erectus'', whereas Multiregionalism asserts that the groups were not isolated, and that there was significant gene flow.
The most important element of this model for theories of race is that it allows a million years for the evolution of ''Homo sapiens'' around the world; this is more than enough time for the evolution of different races. Leiberman and Jackson (1995), however, have argued that the multiregional model nevertheless depends on several assumptions — (1) that marked morphological contrasts exist between individuals found at the center and at the perimeter of Middle Pleistocene range of the genus ''Homo''; (2) that many features can be shown to emerge at the edge of that range before they develop at the center; and (3) that these features exhibit great tenacity through time — each of which "implies a greater degree of racial differentiation than does the Out-of-Africa displacement model."
[Leonard Lieberman and Fatimah Linda C. Jackson (1995) "Race and Three Models of Human Origin" in ''American Anthropologist'' Vol. 97, No. 2, pp. 236-237] Against these assumptions, they argue that regional variations in these features can thus be taken as evidence for long term differences ''among'' genus Homo individuals that prefigure different races among present-day Homo sapiens individuals, and do not necessarily support the multi-regional model.
The out of Africa model
Archaic ''H. sapiens'' are believed by some to have evolved 400,000 to 600,000 years ago. According to the Out of Africa Model, developed by Christopher Stringer and Peter Andrews, modern ''H. sapiens'' evolved in Africa 200,000 years ago and then migrated to Europe and Asia, where it replaced existing hominid species.
[Christopher Stringer and Peter Andrews (1988) "Genetic and Fossil Evidence for the Origin of Modern Humans" in ''Science'' 239: 1263-1268] The Out of Africa Model has gained support by recent, though controversial, research by molecular biologists working with
mitochondrial DNA (mtDNA). Working with mtDNA, molecular biologists constructed a tree representing relations among 133 different types of mtDNA, and argued that the tree is "a genealogy linking maternal lineages in modern human beings to a common ancestral female. After assessing different mtDNA trees (i.e. different ways of organizing the results) they concluded that all were descended from a woman from Africa, dubbed
Mitochondrial Eve. They also calculated that modern Humans may have left Africa during one of two periods: 90,000-180,000 years ago, or 23,000-105,000 years ago; that humans colonized Australia 40,000 years ago, New Guinea 30,000 years ago, and the New World 12,000 years ago.
[Rebecca L. Cann, Mark Stoneking, Allan C. Wilson (1987) "Mitochondrial DNA and human evolution" in ''Nature'' 325: 31-36)]
According to Lieberman and Jackson, the Out of Africa Model has several implications for any understanding of races as biological phenomena. First, "the shallow time dimensions minimize the degree to which racial differences could have evolved." Second, it does present a major distinction between African and Eurasian groups, which "could be used to emphasize the degree of biological differences, and thereby provide support for the race concept."
[Leonard Lieberman and Fatimah Linda C. Jackson (1995) "Race and Three Models of Human Origin" in ''American Anthropologist'' Vol. 97, No. 2, pp. 235] They also observe that "racial stratification is used for initial grouping, and inherent bias is introduced from the very beginning of data collection and interpretation.
[Leonard Lieberman and Fatimah Linda C. Jackson (1995) "Race and Three Models of Human Origin" in ''American Anthropologist'' Vol. 97, No. 2, pp. 238]
Comparison of the two models
Lieberman and Jackson have argued that while advocates of both the Multiregional Model and the Out of Africa Model use the word race and make racial assumptions, none define the term.[Leonard Lieberman and Fatimah Linda C. Jackson (1995) "Race and Three Models of Human Origin" in ''American Anthropologist'' Vol. 97, No. 2, pp. 237] They conclude that
"Each model has implications that both magnify and minimize the differences between races. Yet each model seems to take race and races as a conceptual reality. The net result is that those anthropologists who prefer to view races as a reality are encouraged to do so" and conclude that students of human evolution would be better off avoiding the word race, and instead describe genetic differences in terms of populations and clinal gradations.[Leonard Lieberman and Fatimah Linda C. Jackson (1995) "Race and Three Models of Human Origin" in ''American Anthropologist'' Vol. 97, No. 2, pp. 239]
Systems of categorization preferred depends on scale
Discussions of race, how humans might be divided on an
infraspecies basis, are made more complicated because race research has taken place on at least two scales (global and national) and from the point of view of different research aims. Evolutionary scientists are typically interested in humanity as a whole; and taxonomic racial classifications are often either unhelpful to, or refuted by, studies that focus on the question of global human diversity. Policy-makers and applied professions (such as law-enforcement or medicine), however, are typically concerned only with
genotypic or
phenotypic variation at the national or sub-national scale, and find taxonomic racial categories useful.
These distinctions of research aims and scale can be seen by the example of three major research papers published since
2002: Rosenberg et al. (2002), Serre & Pääbo (2004), and Tang et al. (2005). Both Rosenberg et al. and Serre & Pääbo study global genetic variation, but they arrive at different conclusions. Serre & Pääbo attribute their differing conclusions to experimental design. While Rosenberg et al. studied individuals from populations across the globe without concentrating on particular geographical areas, Serre & Pääbo chose individuals for study from remote and discrete regions. By sampling individuals from major populations on each continent, Rosenberg et al. find evidence for genetic "clusters" (i.e., groupings that might plausibly be equated to earlier races). In contrast, Serre & Pääbo find that with respect to geography human genetic variation is continuous and "
clinal," which denies the presumed clear assignability of all individuals to traditional racial categories. The research interest of Rosenberg et al. is medicine (i.e.,
epidemiology), whereas the research interest of Serre & Pääbo is human evolution. Tang et al. studied genetic variation within the
United States with an interest in whether race/ethnicity or geography is of greater utility to epidemiological research. Tang et al. find that race/ethnic membership (or membership in one of the genetic "clusters" of Rosenberg et al.) is of greater utility within the United States than is one's current geographical location. Further recent research
[An Algorithm to Construct Genetically Similar Subsets of Families with the Use of Self-Reported Ethnicity Information , Andrew D. Skol, Rui Xiao, Michael Boehnke, and Veterans Affairs Cooperative Study 366 Investigators, Department of Biostatistics, University of Michigan, Ann Arbor in ''Am. J. Hum. Genet.'', 77:346-354, 2005.] correlating self-identified race with
population genetic structure
[Structure 2.1 ] echoed the conclusions in Tang. Indeed, the contrasting conclusions between global and national levels of analysis were predicted by Serre & Pääbo:
Three main components of the U.S. population having been drawn from remote parts of the world, the long clinal bridges between the groups that exist in Eurasia have disappeared and those populations seem rather starkly isolated when examined in their new environment.
[''Evidence for Gradients of Human Genetic Diversity Within and Among Continents.'' by David Serre and Svante Pääbo (2004) ''Genome Res.'' 14: 1679-1685 ]
Race as subspecies
With the advent of the
modern synthesis in the early 20th century, many biologists sought to use evolutionary models and populations genetics in an attempt to formalise taxonomy below the species level. The term subspecies is used by biologists when a group of organisms are classified in such a way. In biology the term "race" is very rarely used because it is ambiguous, "'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'".
Generally when it is used it is synonymous with subspecies.
[Templeton, 1998][Keita ''et al.'' 2004][Long and Kittles, 2003] One of the main obstacles to identifying subspecies is that, while it is a recognised taxonomic term, it has no precise definition.
Some species of organisms do not appear to fragment into subgroups, while others do seem to form such subspecific groups. A monotypic species comprises a single group or rather a single subspecies. Monotypic species can occur in several ways:
All members of the species are very similar and cannot be sensibly divided into biologically significant subcategories.
The individuals vary considerably but the variation is essentially random and largely meaningless so far as genetic transmission of these variations is concerned (many plant species fit into this category, which is why horticulturists interested in preserving, say, a particular flower color avoid propagation from seed, and instead use vegetative methods like propagation from cuttings).
The variation among individuals is noticeable and follows a pattern, but there are no clear dividing lines among separate groups: they fade imperceptibly into one another. Such clinal variation always indicates substantial gene flow among the apparently separate groups that make up the population(s). Populations that have a steady, substantial gene flow among them are likely to represent a monotypic species even when a fair degree of genetic variation is obvious.
A ''polytypic'' species has two or more subspecies. These are separate populations that are more genetically different from one another and that are more reproductively isolated, gene flow between these populations is much reduced leading to genetic differentiation.
Morphological subspecies
Traditionally subspecies are seen as geographically isolated and genetically differentiated populations.
Or to put it another way "the designation 'subspecies' is used to indicate an objective degree of microevolutionary divergence"
One objection to this idea is that it does not identify any degree of differentiation, therefore any population that is somewhat biologically different could be considered a subspecies, even to the level of a local population. As a result it is necessary to impose a threshold on the level of difference that is required for a population to be designated a subspecies.
This effectively means that populations of organisms must have reached a certain measurable level of difference in order to be recognised as subspecies.
Dean Amadon proposed in 1949 that subspecies would be defined according to the seventy-five percent rule which means that 75% of a population must lie outside 99% of the range of other populations for a given defining
morphological character or a set of characters. The 75 percent rule still has defenders but other scholars argue that it should be replaced with 90 or 95 percent rule.
[AMADON, D. 1949. The seventy-five percent rule for subspecies. Condor 51:250-258.][MAYR, E. 1969. Principles of Systematic Zoology. McGraw-Hill, New York.][Patten MA & Unitt P. (2002). Diagnosability versus mean differences of sage sparrow subspecies. Auk. vol 119, no 1. p. 26-35.]
When biologists study non-human populations, the standard threshold at which
morphological diversity between two different populations is considered differentiated enough to be classified as subspecies is set at 70-75%. Smith et al. write:
The non-discrete nature of subspecies is evident from their definition as geographic segments of any given gonochoristic (bisexually reproducing) species differing from each other to a reasonably practical degree (e.g., at least 70-75%), but to less than totality. All subspecies are allopatric (either dichopatric non-contiguous ranges or parapatric contiguous ranges , except for cases of circular overlap with sympatry); sympatry is conclusive evidence (except for cases of circular overlap) of allospecificity (separate specific status). Parapatric subspecies interbreed and exhibit intergradation in contact zones, but such taxa maintain the required level of distinction in one or more characters outside of those zones. Dichopatric populations are regarded as subspecies if they fail to exhibit full differentiation (i.e., exhibit overlap in variation of their differentiae up to 25-30%), even in the absence of contact (overlap exceeding 25-30% does not qualify for taxonomic recognition of either dichopatric populations or of parapatric populations outside of their zones of intergradation). Phenotypic adjustment to differing environmental conditions through natural selection is likely the primary factor in divergence of parapatric subspecies, and undoubtedly is involved in some dichopaffic subspecies. The founder effect and genetic drift are involved more in the latter than in the former.
Thus, according to the ''seventy-five percent rule'' two populations represent different subspecies if the morphological differences between them reach between 25-30%.
According to
Sewall Wright, who was born in 1889, there is no question that human populations that have long inhabited separated parts of the world should, in general, be considered to be of different subspecies by the usual criterion that most individuals of such populations can be allocated correctly by inspection. It does not require a trained anthropologist to classify an array of Englishmen, West Africans, and Chinese with 100% accuracy by features, skin color, and type of hair in spite of so much variability within each of these groups that every individual can easily be distinguished from every other. However, it is customary to use the term race rather than subspecies for the major subdivisions of the human species as well as for minor ones.
[Wright, S. 1978. Evolution and the Genetics of Populations, Vol. 4, Variability Within and Among Natural Populations. Univ. Chicago Press, Chicago, Illinois. p. 438]
Humans can be correctly assigned to races at much greater than 75% accuracy on the basis of morphological traits while
chimpanzee subspecies are morphologically indistinct, and difficult or impossible to classify when raised in captivity.
[Stone, A.C., R. Griffiths, S. Zegura, M. Hammer. 2002. High levels of Y chromosome nucleotide diversity in the genus Pan. Proceedings of the National Academy of Sciences 99:43-48.][66. Kaessmann, H., Wiebe, V., Paabo, S. 1999. Extensive Nuclear DNA Sequence Diversity Among Chimpanzees. Science 286:1159-1162.][Wright. 1978. p. 439]
On the other hand in practice subspecies are often defined by easily observable physical appearance, but there is not necessarily any evolutionary significance to these observed differences, so this form of classification is generally not accepted by evolutionary biologists.
Because of the difficulty in classifying subspecies morphologically, many biologists began to reject the concept altogether, citing problems such as:
Subspecies as isolated differentiated populations
Genetic differences between populations of organisms can be determined using the
fixation index of
Sewall Wright, which is often abbreviated to F
ST. This statistic is used to compare differences between any two given populations. For example it is often stated that the fixation index for humans is about 0.15. This means that about 85% of the variation measured in the human population is within any population, and about 15% of the variation occurs between populations.
Citing Smith, Templeton asserts that an F
ST value of 0.25 or 0.30 between populations is a “standard criterion” for subspecies classification. However, Smith doesn't mention the concept of F
ST in his paper, he is discussing variation in morphology and discusses the 75% rule. Templeton reported that
white tailed deer have an F
ST of about 60% and the
grey wolf has an F
ST approaching 90% for mtDNA. The F
ST of grey wolves is 0.168 in autosomal loci, however.
[Wayne, R.K., Lehmann, N., Allard, M.W., Honeycutt, R.L. 1992. Mitochondrial DNA Variability of the Gray Wolf: Genetic Consequences of Population Decline and Habitat Fragmentation. Conservation Biology 6:559-569.][82. Roy, M.S., Gefen, E., Smith, D., Ostrander, E.A., Wayne, R.K. 1994. Patterns of Differentiation and Hybridization in North American Wolflike Canids, Revealed by Analysis of Microsatellite Loci. Molecular Biology and Evolution 11:553-570.] On the other hand, in a paper reporting on the
phylogenetic structure of the Leopard ''
Panthera pardus'' species of Africa and Asia, Uphyrkina ''et al.'' found that 76.04% of mtDNA variation was distributed between leopard populations and 23.96% within populations, for
microsatellite autosomal data, 0.358 (35.8%) of the variation was found between populations.
[Olga Uphyrkina, Warren E. Johnson, Howard Quigley, Dale Miquelle, Laurie Marker, Mitchel Bush, Stephen J. O'Brien (2001) ''Phylogenetics, genome diversity and origin of modern leopard, ''Panthera pardus'''' ''Molecular Ecology'' 10 (11), 2617–2633. ] This compares to a mtDNA F
ST of between 0.24-0.27 (24-27%), and a genomic F
ST of about 0.15 (15%) for humans,
[Celine Becquet, Nick Patterson, Anne C Stone, Molly Przeworski, and David Reich (2007) ''Genetic Structure of Chimpanzee Populations. PLoS Genet.'' 3(4): e66..] The following guidelines were suggested by
Sewall Wright for interpreting F
ST:
“The range 0 to 0.05 may be considered as indicating little genetic differentiation.
The range 0.05 to 0.15 indicates moderate genetic differentiation.
The range 0.15 to 0.25 indicates great genetic differentiation.
Values of FST above 0.25 indicate very great genetic differentiation.”
Wright found differences in F
ST for various species from 0.023-0.501.
[Joseph L. Graves, (2006) ''What We Know and What We Don’t Know: Human Genetic Variation and the Social Construction of Race '' from ''Race and Genomics ''] For humans the F
ST is usually given as 0.15, of this 15% that is distributed between populations about 3-6% is distributed between geographically close populations occupying the same continent and about 6-10% is distributed between more distant continental groups, these figures vary somewhat depending on the type of genetic systems used, but the general observation has been reproduced in numerous studies.
[Lewontin, 2006] This indicates that some of the between population variation for humans is found within any "race" and about 6-10% of variation is found between "races", giving an F
ST of 0.06-0.1 for human "races".
[Pilar Ossorio and Troy Duster (2006) ''Race and Genetics Controversies in Biomedical, Behavioral, and Forensic Sciences'' ''American Psychologist'' 60 115–128 ]
It has also been noted that:
"First, compared with many other mammalian species, humans are genetically less diverse... For example, the chimpanzee subspecies living just in central and western Africa have higher levels of diversity than do humans (Ebersberger et al. 2002; Yu et al. 2003; Fischer et al. 2004)." Human variation is also distributed in an unusual and not easily understood fashion compared to other mammalian species: "The details of this distribution are impossible to describe succinctly because of the difficulty of defining a 'population,' the clinal nature of variation, and heterogeneity across the genome (Long and Kittles 2003).... This distribution of genetic variation differs from the pattern seen in many other mammalian species, for which existing data suggest greater differentiation between groups (Templeton 1998; Kittles and Weiss 2003)."[''The Use of Racial, Ethnic, and Ancestral Categories in Human Genetics Research '' by Race, Ethnicity, and Genetics Working Group. ''Am J Hum Genet.'' 2005 77(4): 519–532.]
"Since the 1980s, there have been indications that the genetic diversity of humans is low compared with that of many other species. This has been interpreted to mean that humans are a relatively young species, so populations have had relatively little time to differentiate from one another. For example, 2 randomly chosen humans differ at ~1 in 1,000 nucleotide pairs, whereas two chimpanzees differ at ~1 in 500 nucleotide pairs.[''DECONSTRUCTING THE RELATIONSHIP BETWEEN GENETICS AND RACE '' Michael Bamshad, Stephen Wooding, Benjamin A. Salisbury and J. Claiborne Stephens. ''Nature Genetics'' (2004) 5:598-609]
"'Race' is a legitimate taxonomic concept that works for chimpanzees but does not apply to humans (at this time). The nonexistence of 'races' or subspecies in modern humans does not preclude substantial genetic variation that may be localized to regions or populations....The DNA of an unknown individual from one of the sampled populations would probably be correctly linked to a population. Because this identification is possible does not mean that there is a level of differentiation equal to 'races'. The genetics of ''Homo sapiens'' shows gradients of differentiation."[Conceptualizing human variation '' by S O Y Keita, 2, R A Kittles1, C D M Royal, G E Bonney, P Furbert-Harris, G M Dunston & C N Rotimi. ''Nature Genetics'' 36, S17 - S20 (2004)]
"Humans are ~98.8% similar to chimpanzees at the nucleotide level and are considerably more similar to each other, differing on average at only 1 of every 500−1,000 nucleotides between chromosomes. This degree of diversity is less than what typically exists among chimpanzees.[''Implications of biogeography of human populations for 'race' and medicine '' by Sarah A Tishkoff & Kenneth K Kidd. ''Nature Genetics'' 36, S21 - S27 (2004)]
"The average proportion of nucleotide differences between a randomly chosen pair of humans (i.e., average nucleotide diversity, or π) is consistently estimated to lie between 1 in 1,000 and 1 in 1,500. This proportion is low compared with those of many other species, from fruit flies to chimpanzees...."[''Genetic variation, classification and 'race' '' by Lynn B Jorde & Stephen P Wooding. ''Nature Genetics' 36, S28 - S33 (2004)]
Another way to measure diversity is to measure
heterozygosity.
Microsatellites are short sequences of DNA that are repeated over a length of DNA, to analyse microsatellites the number of times a sequence is repeated is counted. The variation in repeat number is highly susceptible to mutation, and therefore microsatellites have a high mutation rate. Thus microsatellites are highly polymorphic. Microsatellites are also considered to be selectively neutral. Autosomal
microsatellite diversity (mean heterozygosity) for humans and chimpanzees is similar: humans 0.70-0.76 (based on 60 microsatellites) and chimpanzees 0.73. (based on 8 loci for ''Pan troglodytes'' and 28 loci for ''Pan paniscus'').
[Jorde, L., Rogers, A., Bamshad, M., Watkins, W.S., Krakowiak, P., Sung, S., Kere, J., Harpending, H. April 1997. Microsatellite Diversity and the Demographic History of Modern Humans. Proceedings of the National Academy of Sciences 94:3100-3103.][Reinartz, G.E., Karron, J.D., Phillips, R.B. and Weber, J.L. 2000. Patterns of microsatellite polymorphism in the range-restricted bonobo (''Pan paniscus''): considerations for interspecific comparison with chimpanzees (''P. troglodytes''). Molecular Ecology 9:315-328] On the other hand it has recently been shown that both Western and Central Chimpanzees show a reduced number of heterozygous genotypes, possibly due to inbreeding.
Likewise heterozygosity is influenced by the level of polymorphism at a sampled locus, comparisons of heterozygosity between species are limited to loci that are shared in common, and are affected by the number and selection of loci.
According to a study of the autosomal microsatellite genetic diversity of the Mexican Wolf (using ten microsatellite markers), which also examined 42 dog breeds, the observed heterozygosity of the dog breeds was 0.401 against an expected heterozyosity of 0.616, indicating a divergence from the
Hardy-Weinberg principle.
[Garcia-Moreno, J., Matocq, M., Roy, M., Geffen, E., Wayne, R.K. 1996. Relationships and Genetic Purity of the Endangered Mexican Wolf based on Analysis of Microsatellite Loci. Conservation Biology 10:376-389.] It has been suggested that modern domestic dog breeds originate less than 200 years ago and that the dog was domesticated about 14,000 years ago from a limited number of domestication events, this would serve to decrease genetic diversity in the domestic dog population.
[A.-K. Sundqvist, S. Björnerfeldt, J. A. Leonard, F. Hailer, Å. Hedhammar, H. Ellegren, and C. Vilà. (2006) ''Unequal Contribution of Sexes in the Origin of Dog Breeds. Genetics'': 172(2): 1121–1128. ]
Subspecies as clade
By the 1970s many evolutionary scientists were avoiding the concept of "subspecies" as a
taxonomic category for four reasons:
very few data indicate that contiguous subspecies ever become species * geographically disjunct groups regarded as subspecies usually can be demonstrated to actually be distinct species * subspecies had been recognized on the basis of only 2-5 phenotypic characters, which often were adaptations to local environments but which did not reflect the evolutionary differentiation of populations as a whole * with the advent of molecular techniques used to get a better handle on genetic introgression (gene flow), the picture afforded by looking at genetic variation was often at odds with the phenotypic variation (as is the case with looking at genes versus percentage of epidermal melanin in human populations)These criticisms have coincided with the rise of cladistics
A
clade is a taxonomic group of organisms consisting of a single common ancestor and all the descendants of that ancestor. Every creature produced by sexual reproduction has two immediate lineages, one maternal and one paternal.
[http://www.anthrosource.net/doi/abs/10.1525/an.2006.47.2.7?journalCode=an accessed June 2007] Whereas
Carolus Linnaeus established a taxonomy of living organisms based on anatomical similarities and differences,
cladistics seeks to establish a taxonomy — the
phylogenetic tree — based on genetic similarities and differences and tracing the process of acquisition of multiple characteristics by single organisms. Some researchers have tried to clarify the idea of race by equating it to the biological idea of the
clade:
A
phylogenetic tree like the one shown above is usually derived from
DNA or
protein sequences from populations. Often
mitochondrial DNA or
Y chromosome sequences are used to study ancient human migration paths. These single-locus sources of DNA do not
recombine and are inherited from a single parent. Individuals from the various continental groups tend to be more similar to one another than to people from other continents, and tracing either mitochondrial DNA or non-recombinant Y-chromosome DNA explains how people in one place may be largely derived from people in some remote location. The tree is rooted in the common ancestor of
chimpanzees and humans, which is believed to have originated in
Africa. Horizontal distance corresponds to two things:
#
Genetic distance. Given below the diagram, the genetic difference between humans and chimpanzees is roughly 2%, or 20 times larger than the variation among modern humans.
#
Temporal remoteness of the most recent common ancestor. Rough estimates are given above the diagram, in millions of years. The
mitochondrial most recent common ancestor of modern humans lived roughly 200,000 years ago, latest common ancestors of humans and chimpanzees between four and seven million years ago.
Chimpanzees and humans belong to different
genera, indicated in Blue. Formation of
species and
subspecies is also indicated, and the formation of "races" is indicated in the green rectangle to the right (note that only a very rough representation of human
phylogeny is given, and the points made in the preceding section, insofar as they apply to an "African race", are understood here). Note that vertical distances are not meaningful in this representation.
Most evolutionary scientists have rejected the identification of races with clades for two reasons. First, as Rachel Caspari (2003) argued, clades are by definition monophyletic groups (a taxon that includes ''all'' descendants of a given ancestor) since no groups currently regarded as races are monophyletic, none of those groups can be clades.
For anthropologists Lieberman and Jackson (1995), however, there are more profound methodological and conceptual problems with using cladistics to support concepts of race. They emphasize that "the molecular and biochemical proponents of this model explicitly use racial categories ''in their initial grouping of samples''". For example, the large and highly diverse macroethnic groups of East Indians, North Africans, and Europeans are presumptively grouped as Caucasians prior to the analysis of their DNA variation. This limits and skews interpretations, obscures other lineage relationships, deemphasizes the impact of more immediate clinal environmental factors on genomic diversity, and can cloud our understanding of the true patterns of affinity.
They argue that however significant the empirical research, these studies use the term race in conceptually imprecise and careless ways. They suggest that the authors of these studies find support for racial distinctions only because they began by assuming the validity of race.
For empirical reasons we prefer to place emphasis on clinal variation, which recognizes the existence of adaptive human hereditary variation and simultaneously stresses that such variation is not found in packages that can be labeled ''races''.[''Race and Three Models of Human Origin'', Lieberman and Jackson (1995).]
Indeed, recent research reports evidence for smooth, clinal genetic variation even in regions previously considered racially homogeneous, with the apparent gaps turning out to be artifacts of sampling techniques (Serre & Pääbo 2004). These scientists do not dispute the importance of cladistic research, only its retention of the word race, when reference to populations and clinal gradations are more than adequate to describe the results.
Race and Population Genetics: population and cline
At the beginning of the 20th century, anthropologists questioned, and eventually abandoned, the claim that biologically distinct races are isomorphic with distinct linguistic, cultural, and social groups. Thereafter, the rise of
population genetics led some mainstream evolutionary scientists in
anthropology and
biology to question the very validity of race as a scientific concept describing an objectively real phenomenon. Those who came to reject the validity of the concept race did so for four reasons: empirical, definitional, the availability of alternative concepts, and ethical (Lieberman and Byrne 1993).
The first to challenge the concept of race on empirical grounds were
anthropologists Franz Boas, who demonstrated phenotypic plasticity due to environmental factors (Boas 1912), and
Ashley Montagu (1941, 1942), who relied on evidence from genetics.
Zoologists Edward O. Wilson and W. Brown then challenged the concept from the perspective of general animal systematics, and further rejected the claim that "races" were equivalent to "subspecies" (Wilson and Brown 1953).
One of the crucial innovations in reconceptualizing genotypic and phenotypic variation was anthropologist C. Loring Brace's observation that such variations, insofar as it is affected by
natural selection, migration, or
genetic drift, are distributed along geographic gradations; these gradations are called "
clines" (Brace 1964). This point called attention to a problem common to phenotype-based descriptions of races (for example, those based on hair texture and skin color): they ignore a host of other similarities and differences (for example, blood type) that do not correlate highly with the markers for race. Thus, anthropologist Frank Livingstone's conclusion that, since clines cross racial boundaries, "there are no races, only clines" (Livingstone 1962: 279). In 1964, biologists Paul Ehrlich and Holm pointed out cases where two or more clines are distributed discordantly—for example, melanin is distributed in a decreasing pattern from the equator north and south; frequencies for the haplotype for beta-S hemoglobin, on the other hand, radiate out of specific geographical points in Africa (Ehrlich and Holm 1964). As anthropologists Leonard Lieberman and Fatimah Linda Jackson observe, "Discordant patterns of heterogeneity falsify any description of a population as if it were genotypically or even phenotypically homogeneous" (Lieverman and Jackson 1995).
Population geneticists have debated as to whether the concept of population can provide a basis for a new conception of race. In order to do this a working definition of population must be found. Surprisingly there is no generally accepted concept of population that biologists use. It has been pointed out that the concept of population is central to ecology, evolutionary biology and conservation biology, but also that most definitions of population rely on qualitative descriptions such as "a group of organisms of the same species occupying a particular space at a particular time"
[''What is a population? An empirical evaluation of some genetic methods for identifying the number of gene pools and their degree of connectivity.'' by ROBIN S. WAPLES and OSCAR GAGGIOTTI. ''Molecular Ecology'' (2006) 15, 1419–1439. ] Waples and Gaggiotti identify two broad types of definitions for populations, those that fall into an ''ecological paradigm'' and those that fall into an ''evolutionary paradigm''. Examples such definitions are:
''Ecological paradigm'': A group of individuals of the same species that co-occur in space and time and have an opportunity to interact with each other.
''Evolutionary paradigm'': A group of individuals of the same species living in close enough proximity that any member of the group can potentially mate with any other member.
In a response to Livingston,
Theodore Dobzhansky argued that when talking about "race" one must be attentive to how the term is being used: "I agree with Dr. Livingston that if races have to be 'discrete units,' then there are no races, and if 'race' is used as an 'explanation' of the human variability, rather than vice versa, then the explanation is invalid." He further argued that one could use the term race if one distinguished between "race differences" and "the race concept." The former refers to any distinction in gene frequencies between populations; the latter is "a matter of judgment." He further observed that even when there is clinal variation, "Race differences are objectively ascertainable biological phenomena .... but it does not follow that racially distinct populations must be given racial (or subspecific) labels."
[Theodosious Dobzhansky "Comment" in ''Current Anthropology'' 3(3): 279-280] In short, Livingston and Dobzhansky agree that there are genetic differences among human beings; they also agree that the use of the race concept to classify people, and how the race concept is used, is a matter of social convention. They differ on whether the race concept remains a meaningful and useful social convention.
Richard Lewontin, claiming that 85 percent of human variation occurs within populations, and not among populations, argued that neither "race" nor "subspecies" were appropriate or useful ways to describe populations (Lewontin 1973). Nevertheless, barriers—which may be cultural or physical— between populations can limit gene flow and increase genetic differences. Recent work by population geneticists conducting research in Europe suggests that ethnic identity can be a barrier to gene flow
[Koertvelyessy, TA and MT Nettleship 1996 Ethnicity and mating structure in Southwestern Hungary. Rivista di Antropologia (Roma) 74:45-53][Koertvelyessy, T 1995 Etnicity, isonymic relationships, and biological distance in Northeastern Hungary. Homo 46/1:1-9.][Pettener. D 1990 Temporal trends in marital structure and isonymy in S. Paolo Albanese, Italy. Human Biology 6:837-851.][Biondi, G, P Raspe, GW Lasker, and GGN Mascie-Taylor 1990 Relationships estimated by isonymy among the Italo-Greco villages of southern Italy. Human Biology 62:649-663.]. Others, such as
Ernst Mayr, have argued for a notion of "geographic race"
http://www.goodrumj.com/Mayr.html. Some researchers report the variation between racial groups (measured by
Sewall Wright's population structure statistic F
ST) accounts for as little as 5% of human genetic variation².
Sewall Wright himself commented that if differences this large were seen in another species, they would be called subspecies.
[Wright S. 1978. Evolution and the Genetics of Populations, Vol. 4, Variability Within and Among Natural Populations. Chicago, II: Univ. Chicago Press]
A. W. F. Edwards argued in 2003 that Lewontin's argument ignores the fact that most of the information that distinguishes populations is hidden in the
correlation structure of the data and not simply in the variation of the individual factors. Edwards concludes that it is not true that "racial classification is . . . of virtually no genetic or taxonomic significance" or that "you can't predict someone’s race by their genes".
[Human genetic diversity: Lewontin's fallacy. , Edwards AW., Gonville and Caius College, Cambridge, in ''PubMed'', 2003 Aug;25(8):798-801.] Likewise
Neil Risch of
Stanford University has proposed that self-identified race/ethnic group could be a valid means of categorization in the USA for public health and policy considerations, as a clustering analysis of 326
microsatellite markers can accurately place individuals in the USA into different groups.
[''Genetic Structure, Self-Identified Race/Ethnicity, and Confounding in Case-Control Association Studies '' by Hua Tang, Tom Quertermous, Beatriz Rodriguez, Sharon L. R. Kardia, Xiaofeng Zhu, Andrew Brown, James S. Pankow, Michael A. Province, Steven C. Hunt, Eric Boerwinkle, Nicholas J. Schork, and Neil J. Risch Am J Hum Genet. 2005 February; 76(2): 268–275.][''Categorization of humans in biomedical research: genes, race and disease '' by Neil Risch, Esteban Burchard, Elad Ziv and Hua Tang]'' Genome Biology 2002, 3:comment] While a 2002 paper by
Noah Rosenberg's group makes a similar claim "The structure of human populations is relevant in various epidemiological contexts. As a result of variation in frequencies of both genetic and nongenetic risk factors, rates of disease and of such phenotypes as adverse drug response vary across populations. Further, information about a patient’s population of origin might provide health care practitioners with information about risk when direct causes of disease are unknown." The study uses DNA samples from 52
ethnic groups and statistically groups them into six clusters.
[Noah A. Rosenberg, Jonathan K. Pritchard, James L. Weber, Howard M. Cann, Kenneth K. Kidd, Lev A. Zhivotovsky, Marcus W. Feldman. ''Genetic Structure of Human Populations. Science'' (2002) 298:2381-5]
Conversely Witherspoon ''et al.'' (2007) have shown that while it is possible to classify people into genetic clusters this does not resolve the observation that any two individuals from different populations are often genetically more similar to each other than to two individuals from the same population:
Discussions of genetic differences between major human populations have long been dominated by two facts: (a) Such differences account for only a small fraction of variance in allele frequencies, but nonetheless (b) multilocus statistics assign most individuals to the correct population. This is widely understood to reflect the increased discriminatory power of multilocus statistics. Yet Bamshad et al. (2004) showed, using multilocus statistics and nearly 400 polymorphic loci, that (c) pairs of individuals from different populations are often more similar than pairs from the same population. If multilocus statistics are so powerful, then how are we to understand this finding?
All three of the claims listed above appear in disputes over the significance of human population variation and "race"...The Human Genome Project (2001, p. 812) states that "two random individuals from any one group are almost as different genetically as any two random individuals from the entire world."
Risch ''et al.'' (2002) state that "two Caucasians are more similar to each other genetically than a Caucasian and an Asian", but Bamshad ''et al'' (2004)
[Bamshad, Wooding, Salisbury§ and Stephens (2004) ''Deconstructing the relationship between genetics and race. Nature Reviews Genetics'' 8:598-609. ] used the same data set as Rosenberg ''et al.'' (2002) to show that Europeans are more similar to Asians 38% of the time than they are to other Europeans when only 377 microsatellite markers are analysed.
|colspan="4" align="center"|Percentage similarity between two individuals from different clusters.[The table gives the percentage likelihood that two individuals from different clusters are genetically more similar to each other than to someone from their own population when 377 microsatellite markers are considered from Bamshad ''et al.'' (2004), original data from Rosenberg (2002).]
|-
! x !! Africans !! Europeans !! Asians
|-
! Europeans
| 36.5 || - || -
|-
! Asians
| 35.5 || 38.3 || -
|-
! Indigenous Americans
| 26.1 || 33.4 || 35
|
In agreement with the observation of Bamshad ''et al.'' (2004), Witherspoon ''et al.'' (2007) have shown that many more than 326 or 377 microsatellite loci are required in order to show that individuals are always more similar to individuals in their own population group than to individuals in different population groups, even for three distinct populations.
[''Genetic Similarities Within and Between Human Populations '' by D. J. Witherspoon, S. Wooding, A. R. Rogers, E. E. Marchani, W. S. Watkins, M. A. Batzer, and L. B. Jorde Genetics. 2007 May; 176(1): 351–359.]
Witherspoon ''et al.'' conclude that the answer to the question "How often is a pair of individuals from one population genetically more dissimilar than two individuals chosen from two different populations?" depends on the number of genes studied and the distinctness of the populations. With ten
loci and three distinct populations the answer is about 30%, with 100 loci it is about 20% and with a thousand loci it is about 10%. For individuals from within a group to never be more different to each other than to members of a different groups, thousands of loci need to be studied form geographically separated populations. Witherspoon also concludes that if the world population were studied with it's many closely related groups varying clinally, the use of even 10,000 loci does not produce the answer "never". Witherspoon also makes the observation: "In a similar vein, Romualdi et al. (2002)
[''Patterns of Human Diversity, within and among Continents, Inferred from Biallelic DNA Polymorphisms'' by Chiara Romualdi, David Balding, Ivane S. Nasidze, Gregory Risch, Myles Robichaux, Stephen T. Sherry, Mark Stoneking, Mark A. Batzer, and Guido Barbujani1. ''Genome Res.'' (2002) 12: 602-612 ] and Serre and Paabo (2004)
[''Evidence for Gradients of Human Genetic Diversity Within and Among Continents.'' by David Serre and Svante Pääbo (2004) ''Genome Res.'' 14: 1679-1685 ] have suggested that highly accurate classification of individuals from continuously sampled (and there fore closely related) populations may be impossible."
.
Also, it has been argued that the calculation of within group and between group diversity has violated certain expectations regarding human genetic variation. Calculation of this variation is known as F
ST and Long and Kittles (2003) have questioned the validity of this value as a reproducible statistic. The first problem is that effective population size is assumed to be equal in all instances of the calculation of F
ST, but 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 (2003). ''Human genetic variation and the nonexistence of human races'' (PDF): '''Human Biology, V. 75, no. 4, pp. 449-471.]
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 selected a single population to preserve, 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
They also state that none of the race concepts they discuss are compatible with their results.
These empirical challenges to the concept of race forced evolutionary sciences to reconsider their definition of race. Mid-century, anthropologist William Boyd defined race as:
Lieberman and Jackson (1994) have pointed out that "the weakness of this statement is that if one gene can distinguish races then the number of races is as numerous as the number of human couples reproducing." Moreover, anthropologist Stephen Molnar has suggested that the discordance of clines inevitably results in a multiplication of races that renders the concept itself useless (Molnar 1992).
The distribution of many physical traits resembles the distribution of genetic variation within and between human populations (American Association of Physical Anthropologists 1996; Keita and Kittles 1997). For example, ~90% of the variation in human head shapes occurs within every human group, and ~10% separates groups, with a greater variability of head shape among individuals with recent African ancestors (Relethford 2002).
Characteristics under selective pressure
Prominent exceptions to the common distribution of physical characteristics within and among groups are those under selective pressure, such as skin color. Approximately 10% of the variance in skin color occurs within groups, and ~90% occurs between groups (Relethford 2002). This distribution of skin color and its geographic patterning—with people whose ancestors lived predominantly near the equator having darker skin than those with ancestors who lived predominantly in higher latitudes—indicates that this attribute has been under strong selective pressure. Darker skin appears to be strongly selected for in equatorial regions to prevent sunburn, skin cancer, the photolysis of folate, and damage to sweat glands (Sturm ''et al.'' 2001; Rees 2003). A leading hypothesis for the selection of lighter skin in higher latitudes is that it enables the body to form greater amounts of vitamin D, which helps prevent rickets (Jablonski 2004). Evidence for this hypothesis includes the finding that a substantial portion of the differences of skin color between Europeans and Africans resides in a single gene,
SLC24A5 the threonine-111 allele of which was found in 98.7 to 100% among several European samples, while the alanine-111 form was found in 93 to 100% of samples of Africans, East Asians and Indigenous Americans (Lamason ''et al.'' 2005). However, the vitamin D hypothesis is not universally accepted (Aoki 2002), and lighter skin in high latitudes may correspond simply to an absence of selection for dark skin (Harding ''et al.'' 2000).
Melanin, which serves as the pigment, is located in the
epidermis of the skin, and is based on
hereditary gene expression.
Because skin color has been under strong selective pressure, similar skin colors can result from convergent adaptation rather than from genetic relatedness. Sub-Saharan Africans, tribal populations from southern India, and Indigenous Australians have similar skin pigmentation, but genetically they are no more similar than are other widely separated groups.Furthermore, in some parts of the world in which people from different regions have mixed extensively, the connection between skin color and ancestry has been substantially weakened (Parra ''et al.'' 2004). In Brazil, for example, skin color terms, ranging from black to white, mark racial identity - yet researchers discovered a "significant dissociation" between race and ancestry "estimated by genetic markers" (Parra ''et al.'' 2003).
Considerable speculation has surrounded the possible adaptive value of other physical features characteristic of groups, such as the constellation of facial features observed in many eastern and northeastern Asians (Guthrie 1996). However, any given physical characteristic generally is found in multiple groups (Lahr 1996), and demonstrating that environmental selective pressures shaped specific physical features proves to be difficult, since such features may have resulted from sexual selection for individuals with certain appearances or from genetic drift (Roseman 2004).
In the face of these issues, some evolutionary scientists have simply abandoned the concept of race in favor of "
population." What distinguishes population from previous groupings of humans by race is that it refers to a breeding population (essential to genetic calculations) and not to a biological
taxon. Other evolutionary scientists have abandoned the concept of race in favor of
cline (meaning, how the frequency of a trait changes along a geographic gradient). (The concepts of population and cline are not, however, mutually exclusive and both are used by many evolutionary scientists.)
According to Jonathan Marks,
:By the 1970s, it had become clear that (1)most human differences were cultural; (2) what was not cultural was principally polymorphic - that is to say, found in diverse groups of people at different frequencies; (3) what was not cultural or polymorphic was principally clinal - that is to say, gradually variable over geography; and (4) what was left - the component of human diversity that was not cultural, polymorphic, or clinal - was very small.
:A consensus consequently developed among anthropologists and geneticists that race as the previous generation had known it - as largely discrete, geographically distinct, gene pools - did not exist.
[ Marks, Jonathan (2007) "Grand Anthropological Themes" in ''American Ethnologist'' 34(2): 234, cf. Marks, Jonathan (1995) ''Human Biodiversity: Genes, Race, and History''. New York: Aldine de Gruyter]
In the face of this rejection of race by evolutionary scientists, many social scientists have replaced the word race with the word "
ethnicity" to refer to self-identifying groups based on beliefs concerning shared culture, ancestry and history. Alongside empirical and conceptual problems with "race," following the
Second World War, evolutionary and social scientists were acutely aware of how beliefs about race had been used to justify discrimination, apartheid, slavery, and genocide. This questioning gained momentum in the
1960s during the U.S.
civil rights movement and the emergence of numerous anti-colonial movements worldwide. They thus came to understood that these justifications, even when expressed in language that sought to appear objective, were
social constructs.
[Gordon 1964]
Race and Molecular Genetics: lineages and clusters
Work by molecular biologists such as Cann et al.
[Rebecca L. Cann, Mark Stoneking, Allan C. Wilson (1987) "Mitochondrial DNA and human evolution" in Nature 325: 31-36) ] on mtDNA has led some scientists, such as Johnson et al., to a new definition of race as lineage; after constructing a phylogeny of mtDNA types, Johnson et al. suggested that "the three central types are among those most likely to have been present prior to the formation of the extant human races".
[Johnson MJ; Wallace Dc; Ferris Sd; Rattazzi Mc; Cavallisforza Ll (1983) “Radiation Of Human Mitochondria Dna Types Analyzed By Restriction Endonuclease Cleavage Patterns” ''Journal Of Molecular Evolution'' 19 (3-4): 255-271]. Although most molecular biologists avoid making, or question, using this data to support racial classifications, this view has gained some traction among research in biomedicine, such as Risch et al.
[Risch, N., Burchard, E., Ziv, E. & Tang, H. Categorization of humans in biomedical research: genes, race, and disease. Genome Biol. 3, 1−12 (2003)] and Burchard et al.
[Burchard, E. G. et al. The importance of race and ethnic background in biomedical research and clinical practice. N. Engl. J. Med. 348, 1170−1175 (2003).]
In the case of mtDNA research, lineages consist of people descended from one female ancestor.This work is being supplemented by recent research by molecular biologists studying the human
genome.
[ Nadia Abu el-Haj (2007) Rethinking Genetic Genealogy" in ''American Ethnology'' 34(2): 224] With a genome of approximate 3 billion nucleotides, on average two humans differ at approximately 3 million nucleotides. Some of these
single nucleotide polymorphisms (SNPs) are functional and influence the phenotypic differences between humans, which means that they are also subject to natural selection. However, most of these SNPs are
neutral, meaning they do not express themselves phenotypically and are not subject to natural selection (see
International HapMap Project).
[ Nadia Abu el-Haj (2007) Rethinking Genetic Genealogy" in ''American Ethnology'' 34(2): 224] Because this so-called "junk DNA" is not subject to natural selection, it changes very little over the generations.
[ Nadia Abu el-Haj (2007) Rethinking Genetic Genealogy" in ''American Ethnology'' 34(2): 224] Consequently, scientists can use the distribution of neutral polymorphisms among contemporary humans to map additional "lineages" (in the case of nuclear DNA, descent from an apical male ancestor).
[ Nadia Abu el-Haj (2007) Rethinking Genetic Genealogy" in ''American Ethnology'' 34(2): 224-225] The result has been a new industry in which individuals can send genetic samples to laboratories that identify the person's
Y chromosome or
mtDNA lineage, popularized by scientists such as
Spencer Wells.
[Spencer Wells (2002) ''The Journey of Man: A Genetic Odyssey'', Penguin, UK; Random House, USA]
Genetic data can be used to infer population structure and assign individuals to groups that often correspond with their self-identified geographical ancestry. Recently, Lynn Jorde and Steven Wooding argued that "Analysis of many loci now yields reasonably accurate estimates of genetic similarity among individuals, rather than populations. Clustering of individuals is correlated with geographic origin or ancestry."
[Lynn B Jorde & Stephen P Wooding, 2004, "Genetic variation, classification and 'race'" in ''Nature Genetics'' 36, S28 - S33 Genetic variation, classification and 'race' ]
The inference of population structure from multilocus genotyping depends on the selection of a large number of informative genetic markers. These studies usually find that groups of humans living on the same continent are more similar to one another than to groups living on different continents. Many such studies are criticized for assigning group identity ''a priori''. However, even if group identity is stripped and group identity assigned ''a posteriori'' using only genetic data, population structure can still be inferred. For example, using 377 markers, Rosenberg et al. (2002) were able to assign 1,056 individuals from 52 populations around the globe to one of six genetic clusters, of which five correspond to major geographic regions.
Genetic techniques that distinguish clustering between continents can also be used to describe clustering within continents. However, the study of intra-continental ancestry may require a greater number of informative markers. Indigenous populations from neighboring geographic regions on average share more recent common ancestors. As a result, allele frequencies will be correlated between these groups. This phenomenon is often seen as a cline of allele frequencies. The existence of allelic clines has been offered as evidence that individuals cannot be allocated into genetic clusters (Kittles & Weiss 2003). However, others argue that low levels of differentiation between groups merely make the assignment to groups more difficult, not impossible (Bamshad et al. 2004). Also, clines and clusters, seemingly discordant perspectives on human genetic diversity may be reconciled. A recent comprehensive study has stated: "At the same time, we find that human genetic diversity consists not only of clines, but also of clusters."
[Clines, Clusters, and the Effect of Study Design on the Inference of Human Population Structure http://genetics.plosjournals.org/perlserv/?request=get-document&doi=10.1371%2Fjournal.pgen.0010070]
Summary of different definitions of race
|+ Biological definitions of race (Long & Kittles, 2003) ''et al.''
! Concept || Reference || Definition
|-
| Essentialist || Hooton (1926) || "A great division of mankind, characterized as a group by the sharing of a certain combination of features, which have been derived from their common descent, and constitute a vague physical background, usually more or less obscured by individual variations, and realized best in a composite picture."
|-
| Taxonomic || Mayr (1969) || "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."
|-
| Clade || Levin (2002) || Race "connotes geographic ancestry, by continent or large continental subregion" and "is used to denote continental or subcontinental clades". In "Cladistic taxonomy ... the basic taxon is the genealogical unit, ancestors-plus-line- (or tree) -of-descent, what according to the present analysis races are."
|-
| Population || Dobzhansky (1970) || "Races are genetically distinct Mendelian populations. They are neither individuals nor particular genotypes, they consist of individuals who differ genetically among themselves."
|-
| Lineage || Templeton (1998) || "A subspecies (race) is a distinct evolutionary lineage within a species. This definition requires that a subspecies be genetically differentiated due to barriers to genetic exchange that have persisted for long periods of time; that is, the subspecies must have historical continuity in addition to current genetic differentiation."
|
Current views across disciplines
One result of debates over the meaning and validity of the concept "race" is that the current literature across different disciplines regarding human variation lacks
consensus, though within some fields, such as biology, there is strong consensus. Some studies use the word race in its early
essentialist taxonomic sense. Many others still use the term race, but use it to mean a population,
clade, or
haplogroup. Others eschew the concept of race altogether, and use the concept of population as a less problematical unit of analysis.
In the 19th century, race was a central concept of
anthropology. In 1866,
James Hunt, the founder of the
Anthropological Society of London, declared that anthropology’s primary truth “is the existence of well-marked psychological and moral distinctions in the different races of men.” However, this view was largely rejected by the community of social sciences in the second half of the 20th century.
Scientific support for the Caucasoid, Negroid, Mongoloid terminology of racial classification has diminished over the past century. These terms originally denoted skull types and sprang from the technique known as ''
craniofacial anthropometry'', but these disciplines have been abandoned by the mainstream scientific community. Today they have only two common uses. They are used in ''
forensic anthropology'' as an indicator of ethnicity of skeletal remains. And they can be used as euphemisms for making racially based distinctions that are now regarded as being
racist and baseless by mainstream culture.
Since 1932, some
college textbooks introducing physical anthropology have increasingly come to reject race as a valid concept: from 1932 to 1976, only seven out of thirty-two rejected race; from 1975 to 1984, thirteen out of thirty-three rejected race; from 1985 to 1993, thirteen out of nineteen rejected race. According to one academic journal entry, where 78 percent of the articles in the 1931 ''Journal of Physical Anthropology'' employed these or nearly synonymous terms reflecting a bio-race paradigm, only 36 percent did so in 1965, and just 28 percent did in 1996.
[Leonard Lieberman, Rodney C. Kirk, and Alice Littlefield, "Perishing Paradigm: Race—1931-99," ''American Anthropologist'' 105, no. 1 (2003): 110-13. A following article in the same issue, by Mat Cartmill and Kaye Brown, questions the precise rate of decline, but from their biased perspective agree that the Negroid/Caucasoid/Mongoloid paradigm has fallen into near-total disfavor.] The American Anthropological Association, drawing on biological research, currently holds that "The concept of race is a social and cultural construction. . . . Race simply cannot be tested or proven scientifically," and that, "It is clear that human populations are not unambiguous, clearly demarcated, biologically distinct groups. The concept of 'race' has no validity . . . in the human species".
[American Anthropological Association Statement on Race ]
In an ongoing debate, some geneticists argue that race is neither a meaningful concept nor a useful
heuristic device,
[(Wilson ''et al.'' 2001), (Cooper ''et al.'' 2003) (given in summary by Bamshad ''et al.'' 2004 p.599)] and even that genetic differences among groups are biologically meaningless,
[(Schwartz 2001), (Stephens 2003) (given in summary by Bamshad ''et al.'' 2004 p.599)] on the grounds that more genetic variation exists within such races than among them, and that racial traits overlap without discrete boundaries.
[(Smedley and Smedley 2005), (Helms ''et al.'' 2005), http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-311X2004000300003&lng=es&nrm=iso. Lewontin, for example argues that there is no biological basis for race on the basis of research indicating that more genetic variation exists within such races than among them (Lewontin 1972).]
Other geneticists, in contrast, argue that categories of self-identified race/ethnicity or biogeographic ancestry are both valid and useful,
[(Risch ''et al.'' 2002), (Bamshad 2005). Neil Risch argues: "One could make the same arguments about sex and age! ... you can undermine any definitional system... In a recent study... we actually had a higher discordance rate between self-reported sex and markers on the X chromosome than between genetic structure on microsatellite markers versus racial self-description, had a 99.9% concordance... 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? ... 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"(Gitschier 2005).] that these categories correspond with clusters
inferred from multilocus genetic data,
[(Harpending and Rogers 2000), (Bamshad ''et al.'' 2003), (Edwards 2003), (Bamshad ''et al.'' 2004), (Tang ''et al.'' 2005), (Rosenberg ''et al.'' 2005): "If enough markers are used... individuals can be partitioned into genetic clusters that match major geographic subdivisions of the globe".] and that this correspondence implies that genetic factors might contribute to unexplained phenotypic variation between groups.
[(Mountain and Risch 2004)]
In February, 2001, the editors of the medical journal ''Archives of Pediatrics and Adolescent Medicine'' asked authors to no longer use "race" as an explanatory variable and not to use obsolescent terms. Some other peer-reviewed journals, such as the ''New England Journal of Medicine'' and the ''American Journal of Public Health'', have made similar endeavours.
[ Frederick P. Rivara and Laurence Finberg, "Use of the Terms Race and Ethnicity," ''Archives of Pediatrics & Adolescent Medicine'' 155, no. 2 (2001): 119. For similar author's guidelines, see Robert S. Schwartz, "Racial Profiling in Medical Research," ''The New England Journal of Medicine'', 344 (no, 18, May 3, 2001); M.T. Fullilove, "Abandoning 'Race' as a Variable in Public Health Research: An Idea Whose Time has Come," ''American Journal of Public Health'', 88 (1998), 1297-1298; and R. Bhopal and L. Donaldson, "White, European, Western, Caucasian, or What? Inappropriate Labeling in Research on Race, Ethnicity, and Health." ''American Journal of Public Health'', 88 (1998), 1303-1307.] Furthermore, the National Institutes of Health recently issued a program announcement for grant applications through February 1, 2006, specifically seeking researchers who can investigate and publicize among primary care physicians the detrimental effects on the nation's health of the practice of medical racial profiling using such terms. The program announcement quoted the editors of one journal as saying that, "analysis by race and ethnicity has become an analytical knee-jerk reflex."
[ See program announcement and requests for grant applications at the NIH website, at URL: http://grants1.nih.gov/grants/guide/pa-files/PA-03-057.html.]
A
survey, taken in 1985 (Lieberman ''et al.'' 1992), asked 1,200 American anthropologists how many
disagree with the following proposition: "There are biological races in the species ''Homo sapiens''." The responses were:
physical anthropologists 41%
cultural anthropologists 53%[Bindon, Jim. University of Alabama. "Post World War II . 2005. August 28, 2006.]
The figure for physical anthropologists at
PhD granting departments was slightly higher, rising from 41% to 42%, with 50% agreeing. This survey, however, did not specify any particular definition of race (although it did clearly specify ''biological race'' within the ''species'' ''Homo Sapiens''); it is difficult to say whether those who supported the statement thought of race in taxonomic or population terms.
The same survey, taken in 1999
[http://www.ssc.uwo.ca/psychology/faculty/rushtonpdfs/Lieberman2001CA.pdf], showed the following changing results for anthropologists:
physical anthropologists 69%
cultural anthropologists 80%
In
Poland the race concept was rejected by only 25 percent of anthropologists in 2001, although: "Unlike the U.S. anthropologists, Polish anthropologists tend to regard race as a term without taxonomic value, often as a substitute for population."
["'Race'—Still an Issue for Physical Anthropology? Results of Polish Studies Seen in the Light of the U.S. Findings" by Katarzyna A. Kaszycka. American Anthropologist March 2003, Vol. 105, No. 1, pp. 116-124]
Races as social constructions
Even as the idea of "race" was becoming a powerful organizing principle in many societies, the shortcomings of the concept were apparent. In the Old World, the gradual transition in appearances from one group to adjacent groups emphasized that "one variety of mankind does so sensibly pass into the other, that you cannot mark out the limits between them," as Blumenbach observed in his writings on human variation (Marks 1995, p. 54). As anthropologists and other evolutionary scientists have shifted away from the language of race to the term ''population'' to talk about genetic differences,
Historians,
anthropologists and
social scientists have re-conceptualized the term "race" as a cultural category or
social construct, in other words, as a particular way that some people have of talking about themselves and others. As Stephan Palmie has recently summarized, race "is not a thing but a social relation";
[Palmie, Stephan (2007) "Genomics, Divination, 'Racecraft'" in ''American Ethnologist'' 34(2): 214] or, in the words of Katya Gibel Mevorach, "a metonym," "a human invention whose criteria for differentiation are neither universal nor fixed but have always been used to manage difference."
[Mevorach, Katya Gibel (2007) "Race, Racism and Academic Complicity" in ''American Ethnologist'' 34(2): 239-240] As such it cannot be a useful analytical concept; rather, the use of the term "race" itself must be analyzed. Moreover, they argue that biology will not explain why or how people use the idea of race: history and social relationships will. For example, the fact that in many parts of the United States, categories such as
Hispanic or
Latino are viewed to constitute a race, while others view "Hispanic" as referring to an
ethnic group, has more to do with the changing position of Hispanics in U.S. society, especially in the context of the
civil rights movement and
the debate over immigration.
Race in the United States
:''see also
Admixture in the United States''
The immigrants to the New World came largely from widely separated regions of the Old World—western and northern Europe, western Africa, and, later, eastern Asia and southern Europe. In the Americas, the immigrant populations began to
mix among themselves and with the
indigenous inhabitants of the continent. In the United States, for example, most people who self-identify as African American have some European ancestors—in one analysis of genetic markers that have differing frequencies between continents, European ancestry ranged from an estimated 7% for a sample of Jamaicans to ∼23% for a sample of African Americans from New Orleans (Parra ''et al.'' 1998). Similarly, many people who identify as European American have some African or Native American ancestors, either through openly interracial marriages or through the gradual inclusion of people with mixed ancestry into the majority population. In a survey of college students who self-identified as
white in a northeastern U.S. university, ∼30% were estimated to have less than 90% European ancestry.
[Shriver ''et al.'' 2003]
In the United States since its early history, Native Americans, African-Americans and European-Americans were classified as belonging to different races. For nearly three centuries, the criteria for membership in these groups were similar, comprising a person’s appearance, his fraction of known non-White ancestry, and his social circle.
2 But the criteria for membership in these races diverged in the late 19th century. During Reconstruction, increasing numbers of Americans began to consider anyone with "
one drop" of "Black blood" to be Black.
3 By the early 20th century, this notion of invisible blackness was made statutory in many states and widely adopted nationwide.
4 In contrast,
Amerindians continue to be defined by a certain percentage of "Indian blood" (called ''
blood quantum'') due in large part to
American slavery ethics. Finally, for the past century or so, to be White one had to have "pure" White ancestry. (Utterly European-looking Americans of Hispanic or Arab ancestry are exceptions in being seen as White by most Americans despite traces of known African ancestry.)
Efforts to sort the increasingly mixed population of the United States into discrete categories generated many difficulties (Spickard 1992). By the standards used in past censuses, many millions of children born in the United States have belonged to a different race than have one of their biological parents. Efforts to track mixing between groups led to a proliferation of categories (such as "mulatto" and "octoroon") and "blood quantum" distinctions that became increasingly untethered from self-reported ancestry. A person's racial identity can change over time, and self-ascribed race can differ from assigned race (Kressin ''et al.'' 2003). Until the 2000 census, Latinos were required to identify with a single race despite the long history of mixing in Latin America; partly as a result of the confusion generated by the distinction, 32.9% (U.S. census records) of Latino respondents in the 2000 census ignored the specified racial categories and checked "some other race". (Mays ''et al.'' 2003 claim a figure of 42%)
The difference between how Native American and Black identities are defined today (blood quantum versus one-drop) has demanded explanation. According to anthropologists such as
Gerald Sider, the goal of such racial designations was to concentrate power, wealth, privilege and land in the hands of Whites in a society of White hegemony and White privilege (Sider 1996; see also Fields 1990). The differences have little to do with biology and far more to do with the history of
racism and specific forms of
White supremacy (the social, geopolitical and economic agendas of dominant Whites vis-à-vis subordinate Blacks and Native Americans) especially the different roles Blacks and Amerindians occupied in White-dominated nineteenth-century America. The theory suggests that the blood quantum definition of Native American identity enabled Whites to acquire Amerindian lands, while the one-drop rule of Black identity enabled Whites to preserve their agricultural labor force. The contrast presumably emerged because as peoples transported far from their land and kinship ties on another continent, Black labor was relatively easy to control, thus reducing Blacks to valuable
commodities as agricultural laborers. In contrast, Amerindian labor was more difficult to control; moreover, Amerindians occupied large territories that became valuable as agricultural lands, especially with the invention of new technologies such as railroads; thus, the blood quantum definition enhanced White acquisition of Amerindian lands in a doctrine of
Manifest Destiny that subjected them to marginalization and multiple episodic localized campaigns of extermination.
The political economy of race had different consequences for the descendants of aboriginal Americans and African slaves. The 19th-century blood quantum rule meant that it was relatively easier for a person of mixed Euro-Amerindian ancestry to be accepted as White. The offspring of only a few generations of intermarriage between Amerindians and Whites likely would not have been considered Amerindian at all—at least not in a legal sense. Amerindians could have
treaty rights to land, but because an individual with one Amerindian great-grandparent no longer was classified as Amerindian, they lost any legal claim to Amerindian land. According to the theory, this enabled Whites to acquire Amerindian lands. The irony is that the same individuals who could be denied legal standing because they were "too White" to claim property rights, might still be Amerindian enough to be considered as "breeds," stigmatized for their Native American ancestry.
The 20th-century one-drop rule, on the other hand, made it relatively difficult for anyone of known Black ancestry to be accepted as White. The child of an African-American sharecropper and a White person was considered Black. And, significant in terms of the economics of sharecropping, such a person also would likely be a sharecropper as well, thus adding to the employer's labor force.
In short, this theory suggests that in a 20th-century economy that benefited from sharecropping, it was useful to have as many Blacks as possible. Conversely, in a 19th-century nation bent on westward expansion, it was advantageous to diminish the numbers of those who could claim title to Amerindian lands by simply defining them out of existence.
It must be mentioned, however, that although some scholars of the Jim Crow period agree that the 20th-century notion of invisible Blackness shifted the color line in the direction of paleness, thereby swelling the labor force in response to Southern Blacks' great migration northwards, others (Joel Williamson, C. Vann Woodward, George M. Fredrickson, Stetson Kennedy) see the one-drop rule as a simple consequence of the need to define Whiteness as being pure, thus justifying White-on-Black oppression. In any event, over the centuries when Whites wielded power over both Blacks and Amerindians and widely believed in their inherent superiority over people of color, it is no coincidence that the hardest racial group in which to prove membership was the White one.
In the United States, social and legal conventions developed over time that forced individuals of mixed ancestry into simplified racial categories (Gossett 1997). An example is the "
one-drop rule" implemented in some state laws that treated anyone with a single known African American ancestor as black (Davis 2001). The decennial censuses conducted since 1790 in the United States also created an incentive to establish racial categories and fit people into those categories (Nobles 2000). In other countries in the Americas where mixing among groups was more extensive, social categories have tended to be more numerous and fluid, with people moving into or out of categories on the basis of a combination of socioeconomic status, social class, ancestry, and appearance (Mörner 1967).
The term "Hispanic" as an ethnonym emerged in the twentieth century with the rise of migration of laborers from Spanish-speaking countries to the United States; it thus includes people who had been considered racially distinct (Black, White, Amerindian) in their home countries. Today, the word "Latino" is often used as a synonym for "Hispanic". In contrast to "Latino," "Anglo" is now used in a similar way to refer to the descendants of British colonists, and values and practices derived from British culture.
Race in Brazil
Compared to 19th-century United States, 20th-century
Brazil was characterized by a relative absence of sharply defined racial groups. According to anthropologist Marvin Harris (1989) this pattern reflects a different history and different
social relations. Basically, race in Brazil was "biologized," but in a way that recognized the difference between ancestry (which determines
genotype) and
phenotypic differences. There, racial identity was not governed by a rigid descent rule. A Brazilian child was never automatically identified with the racial type of one or both parents, nor were there only a limited number of categories to choose from. Over a dozen racial categories would be recognized in conformity with all the possible combinations of hair color, hair texture, eye color, and skin color. These types grade into each other like the colors of the spectrum, and no one category stands significantly isolated from the rest. That is, race referred to appearance, not heredity.
Through this system of racial identification, parents and children and even brothers and sisters were frequently accepted as representatives of completely different racial types. In a fishing village in the state of
Bahia, an investigator showed 100 people pictures of three sisters and asked them to identify the races of each. In only six responses were the sisters identified by the same racial term. Fourteen responses used a different term for each sister (Harris 1964: 57). In another experiment nine portraits were shown to a hundred people. Forty different racial types were elicited (Harris 1964: 58). It was found, in addition, that a given Brazilian might be called by as many as thirteen different terms by other members of the community (Harris 1964: 57). These terms are spread out across practically the entire spectrum of theoretical racial types. A further consequence of the absence of a descent rule was that Brazilians apparently not only disagreed about the racial identity of specific individuals, but they also seemed to be in disagreement about the abstract meaning of the racial terms as defined by words and phrases. For example, 40% of a sample ranked ''moreno claro'' ("light" person of primarily European ancestry with dark hair) as a lighter type than ''mulato claro'' ("light" person of mixed European and African ancestry), while 60% reversed this order (Harris 1964: 58). A further note of confusion is that one person might employ different racial terms to describe the same person over a short time span (Harris 1964: 59; Goldstein 1999: 566-568).}
a solid discussion of Brazilian racial terms, see Livio Sansone's ''Blackness Without Ethnicity'' (2003) and France Winddance Twine's ''Racism in a Racial Democracy'' (1998). The choice of which racial description to use may vary according to the relationship (be it personal, class-based, or otherwise) between the speaker and the person concerned and moods of the individuals involved (Harris 1964: 59).
So, although the identification of a person by race is far more fluid and flexible in Brazil than in the U.S., there still are racial stereotypes and prejudices. African features have been considered less desirable; Blacks have been considered socially inferior, and Whites superior (Harris 1964: 59-60). These white
supremacist values seem to be an obvious legacy of European colonization and the slave-based
plantation system (Harris 1964: 54-57). The complexity of racial classifications in Brazil is reflective of the extent of
miscegenation in
Brazilian society, a society that remains highly, but not strictly,
stratified along color lines. Henceforth, the Brazilian
narrative of a perfect "post-racist" country, composed of the "
cosmic race" celebrated in 1925 by
José Vasconcelos, must be met with caution, as sociologist
Gilberto Freyre demonstrated in 1933 in ''Casa Grande e Senzala''.
The Marketing of Race: genetic lineages as social lineages
New research in molecular genetics, and the marketing of genetic identities through the analysis of one's Y'chromasome or MtDNA, has reignited the debate surrounding race. Most of the controversy surrounds the question of how to interpret these new data, and whether conclusions based on existing data are sound. Although the vast majority of researchers endorse the view that continental groups do not constitute different subspecies, and molecular geneticists generally reject the identification of mtDNA lineages with "races", some anthropologists have suggested that the marketing of genetic analysis to the general public in the form of "Personalized Genetic Histories" (PGH) is leading to a new social construction of race.
Typically, a consumer of a commercial PGH service sends in a sample of DNA which is analyzed by molecular biologists and is sent a report, of which the following is a sample
:"African DNA Ancestry Report"
:The subject's likely haplotype L2 is associated with the so-called Bantu expansion from West and Central sub-Saharan Africa east and south, dated 2,000-4,000 years ago .... Between the 15th and 19th centuries C.E, the Atlantic slave trade resulted in the forced movement of approximately 13 million people from Africa, mainly to the Americas. Only approximately 11 million survived the passage and many more died in the early years of captivity. Many of these slaves were traded to the West African Cape Verde ports of embarkation through Portuguese and Arab middlemen and came from as far sough as Angola. Among the African tribal groups, all Bantu-speaking, in which L2 is common are: Hausa, Kanuri, Fulfe, Songhai, Malunjin (Angola), Yoruba, Senegalese, Serer and Wolof.
Although no single sentence in such a report is technically wrong, through the combination of these sentences, anthropologists and others have argued, the report is telling a story that connects a haplotype with a language and a group of tribes. This story is generally rejected by research scientists for the simple reason that an individual receives his or her Y chromasome or mtDNA from only one ancestor in every generation; consequently, with every generation one goes back in time, the percentage of ones ancestors it representes halves; if one goes back hundreds (let alone thousands) of years, it represents only a tiny fragment of one's ancestry. As Mark Shriver and Rick Kittles recently remarked,
:For many customers of lineage-based tests, there is a lack of understanding that their maternal and paternal lineages do not necessarily represent their entire genetic make-up. For example, an individual might have more than 85% Western European 'genomic' ancestry but still have a West African mtDNA or NRY lineage.
Nevertheless, they acknowledge, such stories are increasingly appealing to the general public
[Mark D. Shriver & Rick A. Kittles, "Genetic ancestry and the search for personalized genetic histories" in ''Nature Reviews Genetics'' 5, 611-618 ]. Thus, in his book "Blood of the Isles", however, Bryan Sykes discusses how people who have been mtDNA tested by his commercial laboratory and been found to belong to the same haplogroup have parties together because they see this as some sort of "bond", even thought these people may not actually share very much ancestry.
Through these kinds of reports, new advances in molecular genetics are being used to create or confirm stories have about social identities. Although these identities are not racial in the biological sense, they are in the cultural sense in that they link biological and cultural identities. Nadia Abu el-Haj has argued that the significance of gentetic lineages in popular conceptions of race owes to the perception that while genetic lineages, like older notions of race, suggests some idea of biological relatedness, unlike older notions of race they are not connected to claims about human behavior or character. Abu el-Haj has thus argued that "postgenomics does seem to be giving race a new lease on life." Nevertheless, Abu el-Haj argues that in order to understand what it means to think of race in terms of genetic lineages, one must understand that
:Race science was never just about classification. It presupposed a distinctive relationship between "nature" and "culture," understanding the differences in the former to ground and to generate the different kinds of persons ("natural kinds") and the distinctive stages of cultures and civilizations that inhabit the world.
Abu el-Haj argues that genomics and the mapping of lineages based on junk DNA liberates "the new racial science from the older one by disentangling ancestry from culture and capacity." As an example, she refers to recent work by Hammer et al., which aimed to test the claim that present-day Jews are more closely related to one another than to neighboring non-Jewish populations. Hammer et. al found that the degree of genetic similarity among Jews shifted depending on the locus investigated, and suggested that this was the result of natural selection acting on particular locii. They therefore focused on the nonrecombining Y chromosome to "circumvent some of the complications associeted with selection"
[Hammer, M.F., A.J. Redd, E.T. Wood, M. R. Bonner, H. Jarjanazi, T. karafet, S. Santachiara-Benerecetti, A. Oppenheimer, M.A. Jobling, T. Jenkins, H. Ostrer, and B. Bonne-Tamir (2000) "Jewish and Middle Eastern Non-Jewish Populations Share a Common pool of Y-Chromosome Biallelic Haplotypes" in ''Proceedings of the National Cacademy of Sciences'' 97(12): 6769-6774]. As another example she points to work by Thomas et al., who sought to distinguish between the Y chromosomes of Jewish priests (in Judaism, membership in the priesthood is passed on through the father's line) and the Y chromosomes of non-Jews.
[ Thomas, M. K. Skoprecski, K. Ben-Ami, H. Parfitt, T. Bradman, and D.B. Goldstein (1988) "Oriigins of Old Testament priests" in ''Nature'' 394(6689): 138-140]Abu el-Haj concluded that this new "race science" calls attention to the importance of "ancestry" (narrowly defined, as it does not include all ancestors) in some religions and in popular culture, and peoples' desire to use science to confirm their claims about ancestry; this "race science," she argues is fundamentally different from older notions of race that were used to explain differences in human behavior or social status:
:As neutral markers,
DNA cannot generate cultural, behavioral, or, for that matter, truly biological differences between groups .... mtDNA and Y-chromosome markers relied on in such work are not "traits" or "qualities" in the old racial sense. They do not render some populations more prone to violence, more likely to suffer psychiatric disorders, or for that matter, incapable of being fully integrated - because of their lower evolutionary development - into a European cultural world. Instead, they are "marks," signs of religious beliefs and practices .... it is via biological noncoding genetic evidence that one can demonstrate that history itself is shared, that historical traditions are (or might well be) true."
[ Nadia Abu el-Haj (2007) Rethinking Genetic Genealogy" in ''American Ethnology'' 34(2): 224-225]
The question is, how highly do genetic lineages correlate with self-identified races? Scientists are divided. Some recent research indicates that self-described race is a near-perfect indicator of an individual's genetic profile, at least in the United States. Using 326 genetic markers, Tang et al. (2005) identified 4 genetic clusters among 3,636 individuals sampled from 15 locations in the United States, and were able to correctly assign individuals to groups that correspond with their self-described race/ethnicity (white, African American, East Asian, or Hispanic) for all but 5 individuals (an error rate of 0.14%). They conclude that ancient ancestry, which correlates tightly with self-described race and not current residence, is the major determinant of genetic structure in the U.S. population. Charles Rotimi, of Howard University's National Human Genome center, has highlighted the methodological flaws in such research — that "the nature or appearance of genetic clustering (grouping) of people is a function of how populations are sampled, of how criteria for boundaries between clusters are set, and of the level of resolution used" all bias the results — and concluded that people should be very cautious about relating genetic lineages to their own sense of identity.
[Charles Rotimi (2003) "Genetic Ancestry Tracing and the Abridan identity: A Double-Edged Sword?" in ''Developing World Bioethics'' 3(2): 153-154.]
Thus, in analyses that assign individuals to groups it becomes less apparent that self-described racial groups are reliable indicators of ancestry. One cause of the reduced power of the assignment of individuals to groups is
admixture. Some racial or ethnic groups, especially
Hispanic groups, do not have homogenous ancestry. For example, self-described African Americans tend to have a mix of West African and European ancestry. Shriver et al. (2003)
found that on average African Americans have ~80% African ancestry. Also, in a survey of college students who self-identified as “white” in a northeastern U.S. university, ~30% of whites had less than 90% European ancestry.
[http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1275602]
Moreover, many have criticized this notion of lineage which is based on the identification of one male or one female ancestor while disregarding (because unavailable using genomic technology) countless other ancestors every individual has and shares with others, including people of different "lineages."
[Mark D. Shriver & Rick A. Kittles, "Genetic ancestry and the search for personalized genetic histories" in ''Nature Reviews Genetics'' 5, 611-618 ]
Stephan Palmie has responded to Abu el-Haj's claim that genetic lineages make possible a new, politically, economically, and socially benign notion of race and racial difference by suggesting that efforts to link genetic history and personal identity will inevitably "ground present social arrangements in a time-hallowed past," that is, use biology to explain cultural differences and social inequalities.
[Stephan Palmie (2007) "Genomic Moonlighting, Jewish Cyborgs, and Peircian Abduction" in ''American Ethnologist'' 34(2): 249]
Political and practical uses of race
Race and racism
During
the Enlightenment, racial classifications were used to justify
enslavement of those deemed to be of "inferior", non-White races, and thus supposedly best fitted for lives of toil under White supervision. These classifications made the distance between races seem nearly as broad as that between species, easing unsettling questions about the appropriateness of such treatment of humans. The practice was at the time generally accepted by both scientific and lay communities.
Arthur Gobineau's ''
An Essay on the Inequality of the Human Races'' (1853-1855) was one of the milestones in the new
racist discourse, along with
Vacher de Lapouge's "anthroposociology." They posited the historical existence of national races such as German and French, branching from basal races supposed to have existed for millennia, such as the
Aryan race, and believed political boundaries should mirror these supposed racial ones.
Later, one of
Hitler's favorite sayings was, "Politics is applied biology".Hitler's ideas of racial purity led to unprecedented atrocities in Europe. Hitler and others enacted race laws used to persecute and murder millions of Jews, who were seen as a race. Since then,
ethnic cleansing has occurred in the
Balkans and
Rwanda. ''Ethnic cleansing'' might be seen as another name for the tribal warfare and mass murder that has afflicted human society for ages, but, in modern times, atrocities have regularly been associated with the attempted use of racial inferiority claims to dehumanize some group. Claiming a scientific basis for negative evaluations can give greater credence to such an ideological agenda.
Racial inequality has been a concern of United States politicians and legislators since the country's founding. In the 19th century most White Americans (including
abolitionists) explained racial inequality as an inevitable consequence of biological differences.Since the mid-20th century, political and civic leaders as well as scientists have debated to what extent racial inequality is cultural in origin. Some argue that curr