Does race exist? Anyone asked this question should immediately respond with: Define “race.” While the concept of race is widely regarded as problematic across various scientific and social-scientific disciplines on the grounds that it is scientific obsolete, this is obviously true only of very crude folk conceptions of race. The concept of “race” surely needs to be defined with rigor and precision in a way that goes beyond folk understandings of race, according to which an individual can be accurately pigeonholed as White, Black, Hispanic, etc. but this does not mean that the concept of race is completely useless or obsolete.
To be sure, a taxonomy which views race in terms of discrete, discontinuous differences is going to be problematic scientifically. Instead, if one is to continue using the term “race,” it must be employed in such a way that allows for racial differences to be continuous rather than discrete. If the word continues to be used (and one might take seriously the possibility that it may be fruitful employed in certain contexts), it must be a definition which nonetheless acknowledges that any classification is going to be imperfect and contain interesting exceptions. For example, a significant minority of the members of one race may exhibit both genotypic and phenotypic distinctives that are atypical for that racial group and more similar to those of another racial group.
Racial classification, if it is to continue, must surely be necessarily exhibit the imperfections, irregularities and discontinuities that come from the classification of distributions of continuous, rather than discrete, differences. But the fact that differences are continuous rather than discrete does not mean that it must therefore be utterly arbitrary and useless.
There are clearly geographically identifiable groups of individuals who share common genetic traits. For the purpose of this article, we will bracket the word “race” and instead use the term “genetic ancestry” or “population.” If the argument that the word “race” ought to be dispensed with is to have any plausibility, however, it is not because genetic ancestry has no bearing on someone’s traits, but because “race” is so saddled with a 19th century typological understanding of racial/genetic differences being discrete rather than continuous, that newer language, such as “genetic ancestry,” might be better suited in order to rid ourselves of a discrete view of race, and revise our understanding of population-genetic differences by understanding such difference as continuous rather than discrete.
In other words, while different populations can clearly be very genetically different from one another, this does not mean it is always useful or accurate to simplistically separate races into Black, White, Asian, Hispanic, etc., as though discrete essences inhere in members of each race which clearly separates them from others. To be sure, genes do matter; individuals are different largely because of genes, and individuals in geographical populations oftentimes exhibit important genetic similarities to one another and differences to those outside the population. Let us look at some examples in which folk categories of race become problematic.
It is clear that phenotypic shorthands such as skin color, hair texture, the size and shape of one’s nose, and so one, function as popular markers for folk racial categories. But do these shorthands actually correlate accurately with genotype? The answer is a resounding “it depends.” It all depends on the specific population region being surveyed: According to Parra et al,
“The results of this study have implications for the use of pigmentation as a ‘marker’ of ancestry in admixed populations. Depending on the degree of population structure present in the admixed population, the correlation between constitutive pigmentation and individual ancestry may be strong, weak or even absent”(2004). The researchers “found no correlation between ‘color’ (described as a multivariate evaluation based on skin pigmentation, hair color and texture, and the shape of nose and lips) and African ancestry (based on 10 AIMs) in an admixed sample from Brazil“(2002).
To summarize their research:
Skin pigmentation is a central element of most discussions on ‘race’ and genetics. Research on the genetic basis of population variation in this phenotype, which is important in mediating both social experiences and environmental exposures, is sparse. We studied the relationship between pigmentation and ancestry in five populations of mixed ancestry with a wide range of pigmentation and ancestral proportions (African Americans from Washington, DC; African Caribbeans living in England; Puerto Ricans from New York; Mexicans from Guerrero; and Hispanics from San Luis Valley). The strength of the relationship between skin color and ancestry was quite variable, with the correlations ranging in intensity from moderately strong (Puerto Rico, rho = 0.633) to weak (Mexico, rho = 0.212). These results demonstrate the utility of ancestry-informative genetic markers and admixture methods and emphasize the need to be cautious when using pigmentation as a proxy of ancestry or when extrapolating the results from one admixed population to another(Parra, 2002).
Thus, in the study, there was relatively weak correlation between ancestry and complexion in Mexican Americans and Mexicans, although the correlation was stronger among Puerto Ricans. It was modest among Africans.
It is important to consider the implications of the wide variation in the strength of the correlation between constitutive pigmentation and individual ancestry in these admixed samples. This variability is presumably a reflection of differences in the degree of population structure present in each population or of the levels of pigmentation differences between the parental populations and the number of genes involved. For example, the strong correlation observed in Puerto Ricans seems to indicate that continuous gene flow, assortative mating or both factors are important in this population. On the contrary, the correlation between melanin content and ancestry in Hispanics, though significant, is weak. This is consistent with historical data indicating that this population appeared as a result of a relatively old admixture event and that independent assortment has greatly decreased the association between unlinked markers created by the admixture process…Alternatively, the differences in the extent of the correlation between constitutive pigmentation and ancestry may be due in part to admixture histories involving populations with widely different pigmentation levels. The Puerto Rican individuals have substantial contributions from three parental groups (Europeans, West Africans and Indigenous Americans). The African American and African Caribbean individuals have contributions mainly from West Africans and Europeans, and the Mexican and Hispanic individuals have primarily European and Indigenous American ancestry.
In another similar study:
This work was undertaken to ascertain to what degree the physical appearance of a Brazilian individual was predictive of genomic African ancestry. Using a panel of 10 population-specific alleles, we assigned to each person an African ancestry index (AAI). The procedure was able to tell apart, with no overlaps, 20 males from northern Portugal from 20 males from São Tomé Island on the west coast of Africa. We also tested 10 Brazilian Amerindians and observed that their AAI values fell in the same range as the Europeans. Finally, we studied two different Brazilian population samples. The first consisted of 173 individuals from a rural Southeastern community, clinically classified according to their Color (white, black, or intermediate) with a multivariate evaluation based on skin pigmentation in the medial part of the arm, hair color and texture, and the shape of the nose and lips. In contrast to the clear-cut results with the African and European samples, our results showed large variances and extensive overlaps among the three Color categories. We next embarked on a study of 200 unrelated Brazilian white males who originated from cosmopolitan centers of the four major geographic regions of the country. The results showed AAI values intermediate between Europeans and Africans, even in southern Brazil, a region predominantly peopled by European immigrants. Our data suggest that in Brazil, at an individual level, color, as determined by physical evaluation, is a poor predictor of genomic African ancestry, estimated by molecular markers.
In one case, “observed a significant positive correlation between melanin index and Indigenous American or West African ancestry, but the strength of the relationship was quite variable: Puerto Rico, rho = 0.633; African Americans, rho = 0.440; African Caribbeans, rho = 0.375; Mexico, rho = 0.212).” The relationship among Puerto Ricans was decently high. The relationship among Mexicans was relatively low.
Or in another study:
Genetic association studies can be used to identify factors that may contribute to disparities in disease evident across different racial and ethnic populations. However, such studies may not account for potential confounding if study populations are genetically heterogeneous. Racial and ethnic classifications have been used as proxies for genetic relatedness. We investigated genetic admixture and developed a questionnaire to explore variables used in constructing racial identity in two cohorts: 50 African Americans and 40 Nigerians. Genetic ancestry was determined by genotyping 107 ancestry informative markers. Ancestry estimates calculated with maximum likelihood estimation were compared with population stratification detected with principal components analysis. Ancestry was approximately 95% west African, 4% European, and 1% Native American in the Nigerian cohort and 83% west African, 15% European, and 2% Native American in the African American cohort. Therefore, self-identification as African American agreed well with inferred west African ancestry. However, the cohorts differed significantly in mean percentage west African and European ancestries…and in the variance for individual ancestry…Among African Americans, no set of questionnaire items effectively estimated degree of west African ancestry, and self-report of a high degree of African ancestry in a three-generation family tree did not accurately predict degree of African ancestry. Our findings suggest that self-reported race and ancestry can predict ancestral clusters but do not reveal the extent of admixture. Genetic classifications of ancestry may provide a more objective and accurate method of defining homogenous populations for the investigation of specific population-disease associations
In this case, while ethnic self-identification did correlate with genetic ancestry, it was not able to accurately predict admixture. The average African-American possessed approximately 20% Europeean ancestry, and 10% of African-American possessed at least 50% European heritage.