Empirical Studies of the Concept of Human Race and Genetics

The concept of the human race has been a widely known topic of debate in human genetics as there is a divided conversation on whether race is a biological attribute or a social construct. Throughout different studies, researchers have been trying to decode what the notion of 'race' determines in human genetics and what leads to racist ideologies in the scientific view. In this paper, I will be examining patterns of human genetic variations through different empirical studies and what they indicate in the concept of the human race, population differentiation, and phenotypic differences across populations.

Gravlee believed that human genetic variation does not equal race through the three claims of the classic critique of race. The first claim stated that there is rarely a gradual change in human variation across the genetic boundaries between populations. The second claim said that human genetic variation traits that determine race do not have predictive values in other facets of biology because some human genetic variations are discordant. The third claim stated that human genetic variation is widespread throughout our species, with only minor differences between racially designated groupings.

Gravlee also discussed the issue of resuscitating race, where all they must do is demonstrate that they can detect genetic differentiation between racially defined groups. However, it does not implicitly link racial categories to no genetic differentiation. Gravlee further stated that the conventional racial classification represents only 5-10% of human genetic variation in Lewontin's account. It suggests a level of genetic differentiation that clustering algorithms should detect. Therefore, evidence of gene clustering does not contradict the claim that most human genetic variation occurs within rather than between traditional racial categories. Even though past studies have proven that genetic distance between populations is strongly correlated to geographic distance, Gravlee stated that the correlation could be stronger if the studies take the possibility of migration into account that reflects on these findings. Gravlee used Ramachandran et al.'s study results, demonstrating that geographic distances due to migration traces account for 78% of the variation in genetic distances between populations. Gravlee also mentioned that other empirical studies show that the geographic distance between East African people accounts for 82-85% of the genetic diversity. Therefore, human genetic variations in East Africa are consistent with migration from their geographical origin.

Novembre's research study uses genotyping technology to understand the patterns of human genetic variations in the European population by genotyping European individuals to find genetic differentiation. The European population surveyed 3,192 European individuals in their Population Reference Sample project (POPRES). In the project, he genotype different locus using SNP chip technology. Analyzing the loci from the genotype data and eliminating external factors can designate the individuals' geographical origin. Novembre utilizes the principal component analysis (PCA) to determine population differentiation clusters, and it is feasible that the resolution of the genetic data may exceed that of the available geographic information in some cases. His findings result in analyzing two principal components and their correlation with the geographic axes as PC1 is correlated with north-northwestsouth-southeast Europe populations, and PC2 is correlated with Iberians and all Eastern people.

As a result, PC1 accounts for 0.30% (or first eigenvalue= 4.09) of the variation, which is about twice the amount of variation in PC2, which accounts for 0.15% (or second eigenvalue= 2.04) of the variation. In addition, Novembre also found that in the PC1 axis, there is a decrease in haplotype diversity in the PC1 axis population from south to north. The result based on the PC axes of the geographic map in clusters shows the overlapping of different clusters in different quadrants, which explains how genetically separate the different European races are to the geographical border. However, the clusters still overlap, which parallels genetic diversity to its geography. For example, on the border of Switzerland, there is German-speaking Swiss to the east and Italian-speaking Swiss to the south, but the map shows that both clusters are overlapping. Moreover, his finding shows that in his multiple-regression-based assignment approach, the accuracy to placed individuals of their reported origin was 540 kilometers for 50% of individuals and 840 kilometers for 90% of individuals across all populations. Therefore, the farther the geographical distance of their origin, the more accurate they can pinpoint an individual's origin.

Lewontin observed human genetic diversity in the research study 'The Apportionment of Human Diversity.' His purpose is to show that the genetic variation within alleged human races was far more significant than their variation. To support this, he analyzes phenotypes in 17 protein markers, which are from blood groups of different individuals in raced populations, and assesses their polymorphic locus. Lewontin also included equal numbers of population from African, European, Oceanian, Asian, and American Indian people to avoid bias in the calculation for proportion. Results show that when aboriginals, Amerinds, and Oceanians have been studied, they have consistently been found to have the lowest Hrace, which constitute the lowest average gene frequency over all the populations within these three races. There are very low locus diversities for 'Amerinds are in the 6PGD, Ak, and ABO; aborigines in Lutheran, MNS, and ABO; and Oceanians in Duffy, Kell, and Rh'. Whereas Africans with Duffy loci and the Mongoloids with Lutheran loci are the only cases where one of the three large races has a low diversity. In addition, Hrace also measures heterozygosity within the race; low diversities in Aborigines, Amerinds, and Oceanians suggest genetic isolation and small breeding size effect for these races.

Other findings show Oceanian and Amerind ratios (Hpop Hrace) is smaller than the three large races. Only a small ratio occurs in the Amerinds for Lutheran loci. On the other hand, Caucasians have a higher ratio than the other two large races, but this is due to classifying certain 'Caucasian' populations as one race. Therefore, Lewontin concludes that there is no evidence that sparse aboriginal populations are more genetically isolated from their neighbors than more widely dispersed large races. Hence, the aboriginal population's Hrace values may reflect their early history of being isolated as groups rather than being bred into many sub-groups of ancestors.

On the other hand, Lewontin's findings also show that the Oceanian population is more genetically homogenous than other races. When Lewontin observed the total diversity under categories of within-population, between-population, and between-race components, results found that the average proportion of complete species diversity contained within populations is 85.4%, with the Xm gene having a maximum of 99.7%, and Duffy having a minimum of 63.6%. Thus, the differences between human groups account for less than 15% of total human genetic diversity. Furthermore, the difference between populations within a race accounts for an additional 8.3%, leaving racial classification to account for only 6.3%. This means that 85% of the human genetic diversity is among individuals between populations that racial taxonomy is unjustified or serves no genetic or taxonomic significance.

The concept of race has been observed in different approaches by many researchers attempting to associate the notion of race with human genetics. In Gravlee's account, he believed that human genetic variation does not equal race as the concept of race is insufficient for describing the complex structure of human genetic variation; the human genetic system is most consistent with a geographic model of within-region diversity and clinal variation, with minor discontinuities at geographic barriers detectable by cluster analysis. Novembre's analysis shows the relationship between overlapping clusters 'mirrors' geographical regions of Europe, which is associated with the accuracy of pinpointing individuals' origins with the PCA. Lewontin's conclusion to his study shows that he finds 85% of the human genetic diversity can be found within a population, but remains unjustifiable.