User:J.birch2/sandbox/Racial naturalism

Racial naturalism is a philosophical position regarding the ontology of human races. The racial naturalist maintains that human races are real biological kinds defined by objective patterns of genetic similarity and difference. The naturalist assertion that races are natural, biological kinds effectively implies that the existence and the exact categorisation of races is independent of what anyone might say or think. This can be sharply contrasted with the opposing view held by social constructionists, who believe that races are social, rather than biological kinds. Even more diametrically opposed is racial eliminativism, a theory claiming that races are not real and racial classifications are fictions. Because they are no longer conceptually relevant and can even produce harm it would be better to abandon them. Racial naturalism fell out of favour in the second half of the 20th century, when a consensus formed that human races were not defined by objective patterns of genetic similarity and difference. However, the view has attracted a new generation of defenders in the early 21st century, following the analysis of new genetic data from the Human Genome Diversity Project. Notable defenders of the view include A. W. F. Edwards and Neven Sesardić. In June 2005 Isosorbide dinitrate/hydralazine, also known as BiDil, became the first race-based drug approved by the FDA, to treat heart failure for Black patients. Critics have argued that prescribing medicines on the basis of a patient's race is scientifically flawed and there is no clear consensus among African American scholars about the societal consequences of race-based pharmaceuticals.

Historical background

Origins

Carl Linnaeus's Systema Naturae (1735) 

According to American anthropologist J. Marks, the practice of giving scientific explanations to racial differences originated in the 17th century when science started to being perceived as the most authoritative source of knowledge. As Marks explains, although humans have held "various groups on different degrees of regard" since ancient times, it was not before three centuries ago that scientists started to view differences between humans as due to racial differences. The concept of human races was the product of scientific progress and in particular the rise of biological taxonomy: the practice of classifying living creatures into smaller groups based on shared characteristics. Applying such methods of formal classification to human populations allowed for the diffusion of the concept of human races. According to Marks, this in turn led to the rise of scientific racism, namely "the act of justifying inequalities between natural groups of people by recourse to science", and made room for discriminating various groups of people on basis of their physical differences.

An example of this trend is Swedish botanist Carl Linnaeus' attempt at classifying humans. In his 1758 Systema Naturae, Linnaeus divided the species Homo Sapiens into four geographical sub-species (or 'varieties' as he calls them):

• Homo Sapiens Americanus
• Homo Sapiens Europaeus
• Homo Sapiens Asiaticus
• Homo Sapiens Afer

Linnaeus then assigned various behavioural and physical traits to the subspecies that reflected their 'idealized' characteristics. This means that the characteristics did not necessarily describe individual members of the subspecies, but rather represented their "underlying form or essence". However, as Marks points out, Linneaus simply inscribed "popular or folk prejudices upon the continental groups he was formally defining". For example, humans belonging to the Homo Sapiens Asiaticus sub-species were described by Linnaeus as having a 'melancholic and stern' temperament, 'dark eyes' and as 'being ruled by opinion', whereas Homo Sapiens Europaeus was defined as typically 'hearty and muscular' with 'blonde hair' and as being 'ruled by law'.

In the late 18th century, Linnaeus' work was taken up by Johann Friedrich Blumenbach who limited the classification of humans to being based on physical traits, but then added a ranking of the subspecies instead.

The 19th century saw the emergence of phrenology as a scientific discipline. This discipline attempted to infer mental traits from the physical consitution of human skulls. This made room for explaining racial differences as due to variations on the shape and size of the skulls of members of different human populations. Samuel Morton, a leading phrenologist of that time, built a case for white populations' superiority by analysing the anatomy of the human skulls. Despite the limited technology for reconstructing the brain, Morton inferred that it was possible to identify the size of the brain from that of the skull, and in particular claimed that a larger skull would allow a larger brain. By comparing the skulls of white individuals with those of nonwhite individuals, he found that the former had larger skulls than the latter had. He argued that from such discovery, it could be concluded that white people where superior, because they allegedly had larger brain and a larger brain would imply a greater quality of it, that is, a greater intelligence. In a similar fashion, Morton's colleague Josiah Nott developed the "theory of the fundamental craniological difference and inferiority of the African", which was then used as a means to justify slavery.

In 1854, Count Arthur de Gobineau published an influential essay, in which he developed a theory linking the success of different civilizations through times to the intellects of their leaders. The explanation he gave for the fall of civilizations was that the elite started to interbreed with the masses, resulting in their blood becoming dissipated. To secure the future of current civilizations, Gobineau argued, it was therefore important to recognize "the unequal ability of races" and preserve "the social hierarchy from which it sprang."

However, also in that period Charles Darwin's theory of evolution started to gain influence and was applied by Herbert Spencer to a theory called social darwinism. Social darwinism was not primarily a theory about race. Its premise was that the advance of society was based on competition, which placed civilization over "savagery and barbarism". However, social darwinism used race to explain the state of savagery of the colonized nations and justify the domination of Caucasians over "imperfect nations".

In the beginning of the 20th century, the most influential explanations of racial differences were provided by psychologists. Especially relevant was the development of intelligence tests, whose results were considered a reliable account of a person's mental capacity. American psychologists Lewis Terman and Robert Yerkes interpreted the score generated by an intelligence test reflected a person's inherited "overall mental output". Psychologists claimed to find that Americans were generally 'feeble-minded', but that it looked to be worse in the future, since immigrants arriving to America were also feeble-minded. Charles Davenport developed a theory about the inheritance of "feeble-mindedness’' and claimed to have isolated a recessive gene as the major cause. He claimed that the gene was most prominent among people outside Northern Europe, nonwhites, poor whites of the South and immigrants from Southern or Eastern Europe.

Finally, human genetics as a scientific discipline was also put in play to support the theory of racial naturalism. Charles Davenport argued that since people's lives were determined by their genes, genetics could also explain why certain societies progress while others do not. Davenport took the phrenologist theories one step further, claiming that "it was the genes that determined the structure of brains and skulls, and thus, of the thoughts contained in them". Yale-educated lawyer Madison Grant argued that while the Nordic 'race' was superior in body and mind, he was concerned about the arrival of Jewish and Italian immigrants. He called this a problem of 'racial genetics'. Such claims were used to articulate political demands for eugenics policies, which is the idea that human breeding should be controlled scientifically in order to secure the genetic future of humans.

In the United States, this led to the enactment of sterilization laws in thirty states and to restrictions on the immigration of people who were considered genetically inferior. In Germany, this led to the sterilization of both Jews and Gypsies among groups. After World War II, the influence that the tendency to explain racial differences using scientific theories had had on Nazism led to the enactment of the first UNESCO Statement on Race (see below).

Official statements

The UNESCO Statements on Race

From 1950 to 1967, UNESCO published "four statements on the race question" aimed at disseminating the most up to date scientific knowledge in terms of race, in order to fight racial prejudice. The first of these statements was written in response to Nazi racism, as well as other factors, following World War II. These statements, prepared by experts such as Franklin Frazier, are respectively known as the Statement on Race, published in Paris in July 1950; a Statement on the Nature of Race and Race Differences, published in Paris in June 1951; the Proposals on the Biological Aspects of Race, published in Moscow in August 1964; and the Statement on Race and Racial Prejudice, published in Paris in September 1967.

UNESCO's Statement on Race, Paris, July 1950

Main article: The Race Question

The 1950 UNESCO Statement on Race is a landmark statement on the relation between race and biology. The statement was written by a panel of prominent social scientists, including social anthropologists Claude Levi-Strauss and Ashley Montagu. The aim was to clarify what was scientifically known about race at that time and to correct serious misconceptions.

It consists of 15 paragraphs, each one meant to address some issues about the concept of race in the light of scientific knowledge. One of the main claims is the idea that mankind is only one, and all human beings "belong to the same species, homo sapiens". Within this species, humans have split up in different groups or populations, mainly because of evolutionary factors such as isolation or natural selection. Nevertheless, the differences that exist between groups of humans are far fewer than the similarities between them.

According to biology – the statement says – races are only accidental groups within the species homo sapiens. Their different biological stories have sometimes produced physical differences among them. Such differences are due to differences in the frequency in which some genes appear in a population, compared to another. However, such genetic difference on which the idea of race appeals to, is irrisory when contrasted with the vaste commonality of traits shared within human species. These groups, however, "appear, fluctuate, and often disappear in the course of time by reason of geographic and/or cultural isolation". Nevertheless, the term "race" has been used arbitrarily and in a non-scientific way: namely, to distinguish between different cultural, religious, national, or linguistic groups; since this meaning of the term has no basis in scientific knowledge, "it would be better when speaking of human races to drop the term ‘race’ altogether and speak of ethnic groups".

Moreover, the statement claims that any division within mankind is dynamic rather than static: that there is "no biological justification for prohibiting intermarriage between persons of different ethnic groups", and cultural differences among groups do not depend on the very fact of being members of a certain group. Furthermore, they say that any classification made by anthropologists does not concern mental characteristics, and particularly intelligence, temperament, personality, and character – which are not innate but largely depend on environmental influences and education. Finally, emphasising once again the "unity of mankind", the experts condemn "the myth of 'race'", a "social myth" which has already caused tremendous suffering (i.e., the Holocaust during World War II). The statement also includes the claim that "the biological fact of race and the myth of 'race' should be distinguished. For all practical social purposes 'race' is not so much a biological phenomenon as a social myth".

UNESCO Statement on the nature of race and race differences, Paris, June 1951

As explained in a preamble by L. C. Dunn, a second, revised statement was published in June 1951 because the first one had been criticized for allegedly neglecting the viewpoints of biologists and biological anthropologists and consequently, was not supported by the authorities in these two fields. With the chief conclusions sustained, the second statement was written by a panel of leading evolutionary biologists, geneticists, and biological anthropologists, including Julian Huxley, J.B.S. Haldane, and Theodosius Dobzhansky.

The unity of mankind and the membership of all human beings to only one species – homo sapiens – are also stressed in this second statement. According to the experts, the existing races are merely the result of two sets of processes:

1. the alternation of human genes by natural selection and by occasional changes.

2. the mix and isolation of populations.

They emphasize, once again, that "national, religious, geographical, linguistic and cultural groups do not necessarily coincide with racial groups; and the cultural traits of such groups have no demonstrated connexion with racial traits." They also assert that "the differences among individuals belonging to the same race are greater than the differences that occur between the observed averages for two or more races within the same major group."

Finally, they repeat that mental characteristics, such as intelligence, temperament, and cultural achievements, are not decided by memberships to a certain ethnic group. The statement closes with a reminder that a properly understood conception of race has significant social consequences:

"The denial at any point of this social bond between men and man brings with it disintegration. In this sense, every man is his brother’s keeper. For every man is a piece of the continent, a part of the main, because he is involved in mankind."

Nevertheless, there are also some differences in comparison to the first statement. The second statement no longer suggests that "for all practical social purposes 'race' is [...] a social myth" and denied the so-called "pure" races. It is less sceptical of the existence of races, treating them as a biological "classificatory device. The claim from the first statement that "there is no proof that the groups of mankind differ in their innate mental characteristics" was amended to that there is no evidence to believe that groups of mankind differ in their "innate capacity for intellectual and emotional development."

The 1998 AAA Statement on "race"

The American Anthropological Association (AAA) published a Statement on "Race" on May 17, 1998. The aim of the statement is to present the general position of the majority of anthropologists of the time, although the AAA acknowledged that the statement did not "reflect a consensus of all members of the AAA". In the statement, the AAA addresses the common view that races are natural divisions based on physical differences – which is not supported by scientific knowledge – and argues that "race" is not a biological category. Rather, the concept of "race" stems from historical, social, economic, educational, and political circumstances. The statement provides both historical and biological evidence to establish this claim.

The authors point to the history of colonialism, claiming that the concept of race originated partly in an attempt to "rationalize European attitudes and treatment of the conquered and enslaved people." The concept of race, in fact, has often been accompanied by a social meaning, and it has been used to justify hierarchies and inequalities between different populations – which have been assumed to be "natural or God-given" – and, subsequently, also to justify slavery. Adopting this notion of race, Europeans and Americans have assigned "superior traits with Europeans and negative and inferior ones to blacks and Indians." Later, a similar notion of the concept has been adopted and reinforced by Adolf Hitler and the Nazis to justify "the extermination of 11 million people of 'inferior races'".

The authors of the statement also cite biological findings to support that the variation of genes is greater within racial groups than between them. They claim: "most physical variation, about 94%, lies within so-called racial groups" and that "geographic 'racial' groupings differ from one another only in about 6% of their genes". This claim is based on Richard Lewontin's work, described below. But in fact, this is a misinterpretation of Lewontin's results, since 6% is not the percentage of genes that differ between races, but the percentage of the human genetic diversity that is accounted for by racial classification. Their position seems to be confirmed also by the fact that physical variations from a certain geographic area to another occur only gradually. Furthermore, any physical trait is inherited independently of the others.

The AAA concludes that "the 'racial' worldview was invented to assign some groups to perpetual low status, while others were permitted access to privilege, power, and wealth." In the United States, this biased view has tragically influenced public policies. Therefore, persisting inequalities between "so-called racial groups" are not a biological product but rather a consequence of social, economic and cultural factors. The AAA statement affirms that “any attempt to establish lines of division among biological populations” is “both arbitrary and subjective”.

Arguments against racial naturalism

Arguments against racial naturalism are often developed by appeal to the impossibility of kind essentialism. Proponents of racial scepticism hold that "races" are meaningless because they do not refer to a distinct and essential hereditary property of a given racial group. Upon statistical analysis, some racial sceptics recommend we discard racial naturalism on the basis that "race" could only refer to isolated communities and is therefore biologically and metaphysically inadequate. Others argue that even if racial naturalism has largely been discarded, the term "race" continues as a result of harmful custom. Often proponents of this view discuss biological inadequacy alongside normative and moral concerns regarding the term "race".

Livingstone's arguments

Biological anthropologist Frank Livingstone, in "On the Non-Existence of Human Races," claims that biology provides compelling arguments for "abandoning the concept of race." First suggested by E. O. Wilson and W. L. Brown, the idea that Livingstone's argument rely on asserts that the concept of race is synonymous with the concept of a subspecies. On his account, the classification by race is an inadequate classification for the purpose of molecular biologists. Livingstone further argues that "there are no races, that there are only clines." In Biology, a cline (from the Greek “klinein”, meaning “to lean”), which can be plotted on a map in the same "way that temperature is plotted on a weather map," is a measurable gradient in a single character (or biological trait) of a species across its geographical range. Livingstone believes that clines are more useful than race for representing the variability within human populations because racial classifications do not explain the distribution of genes which are linked to sickle-cell anaemia among humans. The distribution of these genes varies continuously across geographic regions, correlated with the incidence of malaria.

Livingstone begins his argument by discussing the correlation between different genes and the resulting traits. The same "breeding group" may possess different genetic makeups and may come from different geographical areas, which suggest that race cannot be identified with geographical location or the character traits of a group. Livingstone thinks that genetic variation in human populations is discordant, in that different characters vary largely and independently of each other. In other words, the geographic distribution of one gene tells very little about the geographic distribution of some other gene. For instance, the geographic distribution of different populations' melanin production (gene 1) forms a very different mapping from the geographic distribution of different populations' HbS allele frequency (gene 2). As a result, the patterns of genetic variation change drastically depending on the relevant character or gene being analysed. Livingstone thus claims that there is no non-arbitrary way to partition human populations into races-- the classification depends on an arbitrary choice of relevant characters. For him, dividing homo sapiens obscured rather than clarify genetic variation. He contends that it is "impossible to divide a single species into groups larger than the panmictic population." This is what he calls the "discordance problem."

Livingstone then discuss how race has been misused in explaining human variability. He points out that the presence of a specific "blood group gene or hair form" in a human population of a particular region is often explained as being a racial character. This type of explanation cites the "close common ancestry" of the given population as a reason why the gene is prevalent in that region and not in the rest of humanity. Livingstone claims that many characteristics that were believed to have such a racial explanation "have been found in many widely separated populations" and further suggest that facts about ancestry and migration alone do not adequately explain the geographic distribution of these genes. He believes that, instead of explaining human variation in terms of races, we should instead use "the mathematical theory of population genetics" and causal processes such as "mutation, natural selection, gene drift, and gene flow". As such racial categories result in the "explanation problem."

Dobzhansky's reply to Livingstone

Evolutionary biologist Theodosius Dobzhansky responds to Livingstone, arguing that we can regard all genetic variances between populations as racial differences. Although these racial differences are discoverable as biological phenomena, we should only label some of these racially different populations as races. Dobzhansky considers it convenient to label genetically distinct populations as races if one wants to write and speak about them.However, he also acknowledges that populations have been labelled races for malign reasons rather than for mere convenience. Notwithstanding, he believes that it is unwise to abandon the concept of races altogether as it would cause confusion and "play into hands of race bigots".

Livingstone´s reply to Dobzhansky

For Livingstone, Dobzhansky´s distinction between racial differences (biological phenomenon of genetic variance between population) and race (an arbitrary label) does not map onto the ordinary usage of these words. Furthermore, Livingstone argues that Dobzhansky´s conception of race, as a label to distinguish genetically different populations, is confusing, as the number of different races would be equal to the number of genes. For example, there could be a race of the "high-colour blind" or those with "high sickle cell gene frequency".. Lastly, Livingstone rejects Dobzhansky claim that his stance on abandoning the concept of race would embolden race bigots -- he wonders "how a position which denies the validity of a concept supports anyone using that concept".

Lewontin's arguments

In 1972, American biologist and geneticist Richard Lewontin published “The Apportionment of Human Diversity,” in which he presented a series of scientific findings which he thought successfully refuted racial naturalism. In his article, Lewontin addressed whether the remarkable genetic differences between races, on which racial naturalists based their claims, really existed. The results of his study indicate that only 6.3% of the differences in the genes of the population sample could be explained by race. He argued that if racial naturalism were true, the percentage by which race accounts for genetic diversity would be at least 10% higher.

Lewontin divided the study sample of humans in 7 races (Caucasian, African, Mongoloid, South Asian, Native Americans, Pacific Islanders, Australian Aborigine) and each race again in populations (Caucasians, for example, were subdivided in Arabs, Armenians, Basques, etc). Lewontin took samples of subjects' blood and identified gene differences in 17 key genes by analysing gene-associated protein variants. This gave gene frequencies for the 7 races, which were then compared against conventional racial groupings.

The results of the diversity measure showed that 85.4 % of the total genetic diversity among humans was contained within populations. Therefore, a maximum of 14,6 % was accounted for by differences between human groups (i.e. race and populations). Since 8.3% of that 14.6 % represented the diversity of populations within the same race, only 6.3% of genetic differences answered to racial classifications. Additionally, Lewontin explained that since he gave the same weight to every one of the 7 races, which meant that some were largely overrepresented, the percentage of genetic diversity that could be explained by racial diversity might be even less than 6.3%.

Lewontin claimed that his data stands against canonical taxonomies of race. For instance, if race classification were dictated by gene frequencies from the data in Lewontin's paper, Sámi people would be in the same racial groups as certain African groups. Furthermore, genetic diversity between races would increase if different groups were to be separated out or subsumed under groupings that are very different from how races are usually grouped. The racial component of the difference between groups would increase if Urdu and Hindustani people were grouped under the same race and if Melanesians were to be grouped under a different race than Oceanic people.

Lewontin concluded that:

“It is clear that our perception of relatively large differences between human races and subgroups, as compared to the variation within these groups, is indeed a biased perception and that, based on randomly chosen genetic differences, human races and populations are remarkably similar to each other, with the largest part by far of human variation being accounted for by the differences between individuals."^[9]

Yudell et al.'s arguments

Michael Yudell, Dorothy Roberts, Rob DeSalle, and Sarah Tishkoff argue that "the use of biological concepts of race in human genetic research – so disputed and so mired in confusion – is problematic at best and harmful at worst". They suggest biologists should look for new and more appropriate concepts such as ancestry.

Their claim rests on three arguments. First, they raise the concern that "phylogenetic and population genetic methods do not support a priori classifications of race". Racial categories are "genetically heterogeneous" and "lack clear-cut boundaries", yet this is sometimes poorly understood by medical practitioners and leads to under/over-diagnosis. Second, the use of racial categories by scientists is misinterpreted by the public. This contributes to racist beliefs, so much that leading human population geneticists felt compelled to publicly refute claims about the genetic basis of social differences. Finally, they claim "use of the race concept in genetics ... will not be obviated by new technologies." In other words, their major suggestion can be divided in an epistemic and a social concern. On the one hand, they claim that the use of the concept of race in human genetic research is "problematic" mainly from an epistemic perspective, as it is scientifically inaccurate. On the other hand, "at worst", the use of this concept could become socially harmful, as it would "continue to fuel racist beliefs".

Notably, the authors offer the important distinction between ancestry and race, for the two are usually wrongly used interchangeably in U.S. census surveys. Ancestry is a process-based concept, a statement about an individual’s relationship to another individuals in their genealogical history; thus, it is a very personal understanding of one’s genomic heritage. Race, on the other hand, is a pattern-based concept that has led scientists and laypersons alike to draw conclusions about hierarchical organization of humans, which connect an individual to a larger pre- conceived geographically circumscribed or socially constructed group.

The authors make two recommendations regarding the future of science and the use of the concept of race. They argue that scientific journals and professional societies should encourage using different terminology – like "ancestry" or "population", instead of "race" – in order to avoid confusion, contradiction and inconsistency within the terminology of race. In this way they hope racial classification will phase out. Furthermore, they call for the US National Academies of Sciences, Engineering, and Medicine to convene a panel of experts "from biological sciences, social sciences, and humanities to recommend ways for research into human biological diversity to move past the use of race as a tool for classification in both laboratory and clinical research" . Furthermore, such an effort "would bring stakeholders together for a simple goal: to improve the scientific study of human difference and commonality" .

Ludovica and Bacchini's argument

The risk of death from complex diseases is sometimes patterned along racial lines. Ludovica and Bacchini aim to investigate the significance of racial self-identification as a variable in the research into the aetiology of complex diseases. They distinguish between race-based studies (RBS) and race-neutral studies (RNS) to make this investigation clearer. RBS involves studies investigating the aetiology of complex diseases that use race as a relevant variable in their study. These studies assume race to be a proxy for specified or unspecified causal factors resulting in disease. Conversely, RNS involves investing the aetiology of complex diseases in which race is not a relevant variable, and is not a proxy for a specified or unspecified causal factor resulting in disease. The distinction between RBS and RNS is explicated where RBS tend to adopt the genetic hypothesis, as they assume genetic differences covarying with genetic ancestry, in which self-identified races are supposed to be good proxies, largely cause differences in risk to complex diseases. However, Ludovica and Bacchini aim to show that the genetic hypothesis is not an indisputable notion and that the idea that self-identified races are proxies for any causal factors leading to complex diseases is mistaken. But, this does not entail self-identified races are not useful in research concerned with the aetiology of complex diseases. Through RNS biomedics have gathered support for the contribution of non-genetic variation to the risk of complex diseases. Therefore, self-identified races can play an essential, nongenetic role in encompassing the multifaceted effects of both past and present racism on people’s health by acting as proxies for risk-related environmental and epigenetic variation.

In Defence of Racial Naturalism

Racial naturalism is a biological conception of race as a natural kind. Ron Mallon lays out the recent philosophical discourse regarding race. He describes the racial naturalist position as defending the existence of "biobehavioural essences": innate, natural or perhaps hereditary features, such that these properties are biologically exclusive and distinct to members of a race. According to the racial naturalist these properties are also able to explain behavioural or cultural dispositions of individual members of racial groups. This type of strong racial naturalism has largely been refuted by both philosophers and scientists. However, some philosophers have recently endorsed the possibility that biological groups could exist which would apparently merit the revival of the term race. This new form of racial naturalism is usually understood in terms of evolutionary mechanisms and it is described by Sesardic as "biologically informed but non-essentialist" .

Human Genome Diversity Project

A map showing the 52 source locations of the samples used in the HGDP. Results from the analysis of the sample are mapped, as well as displayed below the map. It might be argued that, because the map shows that the 52 populations can be roughly split into 6 distinct groups which align with geographical regions, it lends support to racial naturalism.

Following the dwindling tide of support for racial naturalism in the 20th century, largely due to the aforementioned findings presented by Lewontin and Livingstone, the 21st century has seen the emergence of more powerful experimental technology, allowing for a larger scale of genetic data to be harnessed. The most salient of these is the Human Genome Diversity Project, which makes use of multi-loci analysis to analyse correlations across several loci simultaneously, as opposed to Lewontin's single-locus statistics, which took a 'locus-by-locus' approach. This experiment "studied human population structure using genotypes at 377 autosomal microsatellite loci in 1056 individuals from 52 populations." Essentially, analysing all 377 genetic traits together, instead of considering 17 of them individually (like Lewontin), allowed the identification of 6 main genotypic clusters, and five of these correspond to major geographic regions: Africa, Eurasia, East Asia, Oceania, and America. Rosenberg et al. also computed the proportion of genetic variation among these five clusters ($\sigma _{a}^{2}$) compared to variation among the 52 populations ($\sigma _{b}^{2}$) and all individuals ($\sigma _{c}^{2}$). Together they make the total genetic variation ($\sigma ^{2}$). Their findings were as follows:

$\sigma ^{2}=\sigma _{c}^{2}+\sigma _{b}^{2}+\sigma _{a}^{2}$

$1=0.932+0.025+0.043$

Although ($\sigma _{a}^{2}$) is comparatively small, it has been argued to be sufficient to establish that the human population can be divided into the five major groups mentioned above. As such, this study has been purported to lend increasing support for racial naturalism, because of its seemingly naturalised and legitimised depiction of racial classification. However, Rosenberg's reserach project has been widely criticised on methodological grounds. A replication study by Tishkoff et al. has found that if 134 instead of 52 ethnic groups are examined, one obtains five different racial categories which do not comply with the US racial groups. Tishkoff et al. demonstrated that by altereing the methodological approach to genetic clustering analysis, one can prove that the five categories should be Caucasians, Mongloids and three distinct clusters of black Africans. Furthermore, Kittles and Weiss criticised the use of Isolation by distance in the Rosenberg et al. study, and argued it is based on biased geographic sampling. Spencer qualified this claim by noting that half of the sample would be of African and New Guinean origin, had it been strictly randomly selected. Hence, the findings of the Human Genome Diversity Project have by no means resulted in a consensus that races are indeed biological, natural kinds. Rather, a new debate has ensued, thereby revealing several limitations of the studies in question.

Biological Racial Realism

Quayshawn Spencer is a contemporary defender of "biological racial realism", a term he prefers to racial naturalism. He takes the view that the five continental genotypic clusters identified by Rosenberg et al. (African, Eurasian, East Asian, Native American, Oceanic) are biologically real. He ascribes the origin of this partition to the German anthropologist Johann Friedrich Blumenbach, which is why Spencer suggests to name it 'the Blumenbach partition'. Furthermore, these clusters are 'races' in the American sense of the word . Spencer argues that the five racial categories are what constitutes the "racial discourse" in the US. He supports this claim by citing that 93.8% of people have identified with only one of the 5 groups in the 2010 US census, although they had the option to identify with two or more categories. He argues that philosophers of race often reject the view that the US meaning of 'race' is biologically real, and thus deny that the definition of race provided by the Office of Management and Budget can be found in the US population. Spencer argues that these philosophers have four common objections to scholars who "interpret recent human genetic clustering results in population genetics as evidence for biological racial realism" . He states that these four common objections are either semantic or metaphysical.

Semantic objections

• The discreteness objection states that racial classifications (i.e. US racial groups) cannot be applied to humans because create mutually exclusive categories. Hence, they do not allow for identification with more than one group. One argument Spencer gives for this claim is that even if there had been mutually exclusive groups, due to "genetic admixture" they would not exists anymore. This claim stands in contrast to Graves who argued that racial categories had never been biologically real in the history of human kind.

• The visibility objection claims that US racial groups cannot be defined by visible traits, such as skin colour and physical attributes.. It is argued that because "human continental populations are defined according to geography and ancestry", a mismatch develops "between the meanings of the US race terms and human population terms" This view is espicially supported by the philosophers Joshua Glasgow and Naomi Zack. Glasgow defends his view by stating that "each race, by and large, has a distinctive set of visible traits which is conceptually non-negotiable" . Zack argues that "ancestral genetic tracking material has no effect on phenotypes, or biological traits of organisms". Kitcher sees visible phenotypical differences as the necessary result of in-breeding in geographically limited places over time, however does not argue that these differences must correspond to US racial groups.

Metaphysical objections

• The very important objection claims that being a biological realist about US racial groups requires evidence of the biological importance of this classification. Although studies, such as Rosenberg et al. , have found overlaps between US racial groups and genetic patterns across the human population, they have not established the importance of the division for contemporary biology. This view is held by Philosophers of Science such as John Dupré, who believes that no matter which racial categories might be verifiable, they do not form "significant biological kinds". According to Spencer, biological importance is established by the existence of e.g. subspecies, clades and high genetic variation, all of which US racial groups do not seem to have .

• The objectively real objection states that biological racial groups as defined in the US are not real because they cannot exist independently of "human interest, belief, or some other mental state of humans" . The objection goes on to state that US racial groups are dependent on some mental states of humans, which suggests a social constructivist view of race. On these grounds, Root advanced his anti-realist view of race by stating "there are no biological races, only man-made races". Other proponents of this second metaphysical objection include Naomi Zack and Ron Sundstrom.

Spencer's criticism

Racial naturalists, such as Quayshawn Spencer, have responded to each of these objections with counter-arguments.

• Spencer does not agree that racial naturalism is false on the grounds that membership in US racial groups is discrete, while membership in continental populations is continous. He shows that in two recent studies "a critical mass of Americans" does not believe they belong to only one race. One study, by Guang Guo (2014), showed that 62% of people with some sub-Saharan African ancestors do not identify as "black" (i.e. choose the one-drop rule). Instead they identified as part of at least two racial groups. Hence, according to Spencer, US racial groups need not be seen as discrete and therefore comply with the overlaps between continental populations.

• As to the visibility objection, Spencer admits that some racial discourses require visible groups, but disagrees that this is a requirement in the US racial discourse. He argues this by showing that according to the US Census Bureau 'Blacks' and 'Pacific Islanders' are races that Americans acknowledge. He claims that Malanesians, who should define as 'Pacific Islanders', fit well within the commonly visible phenotypes among 'Blacks'. Hence, the US racial discourse does not support the claim that each race must possess a distinctive set of visible traits.

• Spencer also doubts that wether or not US racial groups are importance to contemporary biology is not a necessary condition for them to be biologically real. What is important is to provide an argument against 'biological racial anti-realism'. One example for this would be the Rosenberg et al. study, which supports the view that the five US racial groups can be genetically verified. However Spencer admits that although one might as well find evidence for more or fewer groups, the fact that five groups can be established, negates the 'biological racial anti-realist' view that no groups can be genetically identified.

• As to the objectively real objection, Spencer claims that we should study whether an entity is biologically real or not real, instead of biologically real or socially constructed. He supports this view by arguing that biologically real entities are in part socially constructed. Hence, in order to accurately capture real biological entities, social factors must also be considered. This means that biological realism and social constructivism are not contradictory claims. Spencer suggests the contrast that should be studied is that between bological racial realism and biological racial anti-realism.

David E. Reich New York Times article

David Reich, professor at the Harvard department of genetics, has argued that studies on biological differences between human populations are of vital importance in medicine. To the concerns that there is a possibility of using research in this field to justify discriminatory and evil acts (e.g. in the past, slave trade or the genocide of Jews during Nazism) or racist prejudices, he replies that it is impossible to ignore the average genetic differences among "races" mainly because of their medical relevance and the benefits of their acknowledgment.

His main thesis is supported by the results of his own research, showing that the existence of genetic differences between populations can explain differences in prostate cancer rates in African-American men compared to Europeans. The study proved the existence of a location in the genome with 2.8 percent more African ancestry than the average. Reich argues that the research conducted identified real risk factors for disease that differed in frequency across the populations. These type of discoveries have the potential to improve health and save lives. Therefore, even though the research may be conducted by using socially constructed racial categorisation, the results are real and meaningful and thus should not be neglected. His claim is that it is clear that there are some differences in races, just like there are differences between males and females.

He argues that instead of neglecting these differences and inviting "racist misuse of genetics", scientists should make the findings explicit without prejudging the outcome. Furthermore, he calls for the same treatment for races regardless of their inherent differences - “We should both recognize that genetic differences between males and females exist and we should accord each sex the same freedoms and opportunities regardless of those differences.”

A.W.F. Edwards and Lewontin's Fallacy

Popular scientific articles on human genetics state that 85% of total genetic diversity can be attributed to individual differences within populations while only 15% to differences between populations. This claim can be traced back to Lewontin's (1972) paper "The Apportionment of Human Diversity" and affirms the assumption, prevalent in the social sciences, that there is no genetic basis for racial categorization. A.W.F. Edwards rejects such a conclusion and claims that Lewontin "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 accepts Lewontin's statistical analysis of variation within and between populations. However, he claims that it does not follow that race is a meaningless concept. Human racial categorization may have no social value, but it is wrong to state that it is of "virtually no genetic or taxonomic importance". Edwards reasons as follows: "However small the racial partition of total variation may be, if such racial characteristics as there are highly correlated with other racial characteristics, they are by definition informative and therefore of taxonomic significance".

Edward's view could be illustrated with a simple mathematical example by Neven Sesardic, where

• X alone is a bad predictor of group membership (i.e. triangles or squares)
• Y alone is also a bad predictor of group membership
• Yet X + Y is an excellent predictor of group membership
• All triangles are such that X + Y > 3, whereas all squares are such that X + Y < 3.

Edwards’s point is that human populations may be like this: objective genotypic clusters located in different regions of ‘genotypic space’, which are impossible to see when we look at individual genetic markers in isolation.

As such, although Edwards does not appear to disagree with Lewontin's actual results, he instead challenges Lewontin's premise that if racial classification is biologically real, it should be able to explain a considerable portion of human genetic diversity at any single locus. As shown above, he asserts that the classification may only start displaying any predictive power when several loci are analysed together.

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