The Apportionment of Human Diversity

By the 1960s, anthropologists such as Frank B. Livingstone had concluded that "there are no races, there are only clines" – smooth gradients of genetic variation in a species across its geographic range. Lewontin's mentor Theodosius Dobzhansky challenged this, arguing that there are human discrete populations that can be distinguished by differences in the frequency of genetic traits, which he called races. At that time the debate was largely semantic, stemming from their different ideas about what race is and how it would be manifested in humans genetics. The evidence that was available to Livingstone and Dobzhansky was mostly limited to qualitative observations of phenotypes thought to express genetic variation (such as skin colour). Foreshadowing his later work on human genetic variation, he also emphasised that, because there will always be measurable differences between any two populations, it is the degree of difference compared to other axes of variation that will determine whether a grouping is biologically significant. "The Apportionment of Human Diversity" was published in a volume dedicated to Simpson, perhaps prompting Lewontin to recall this previous work. ==Findings==

Lewontin performed a statistical analysis of the fixation index (FST) in populations drawn from seven classically defined "races" (Caucasian, African, Mongoloid, South Asian Aborigines, Amerinds, Oceanians, and Australian Aborigines). At that time, direct sequence data from the human genome was not sufficiently available, so he instead used 17 indirect markers, including blood group proteins. Lewontin found that the majority of the total genetic variation between humans (i.e., of the 0.1% of DNA that varies between individuals), 85.4%, is found within populations, 8.3% of the variation is found between populations within a "race", and only 6.3% was found to account for the racial classification. Numerous later studies have confirmed his findings. Based on this analysis, Lewontin concluded, "Since such racial classification is now seen to be of virtually no genetic or taxonomic significance either, no justification can be offered for its continuance." ==Reception==

In a 2003 paper titled "Human Genetic Diversity: Lewontin's Fallacy", A. W. F. Edwards criticized Lewontin's conclusion that the practice of dividing humanity into races is taxonomically invalid because any given individual will often have more in common genetically with members of other population groups than with members of their own. Edwards argued that this does not refute the biological reality of race since genetic analysis can usually make correct inferences about the perceived race of a person from whom a sample is taken, and that the rate of success increases when more genetic loci are examined. A 2007 paper in Genetics by David J. Witherspoon et al. also concluded that the two arguments are in fact compatible, and that Lewontin's observation about the distribution of genetic differences across ancestral population groups applies "even when the most distinct populations are considered and hundreds of loci are used". In a 2014 paper, Rasmus Grønfeldt Winther argues that "Lewontin's fallacy" is effectively a misnomer, as there really are two different sets of methods and questions at play in studying the genomic population structure of our species: "variance partitioning" and "clustering analysis". According to Winther, they are "two sides of the same mathematics coin" and neither "necessarily implies anything about the reality of human groups". ==Legacy==

Many subsequent studies confirmed Lewontin's main finding. The paper was not frequently cited in the years following its publication. Fifty years after its publication, the paper was found to be frequently referenced in social media. and a section of the book Remapping Race in a Global Context was devoted to discussing Lewontin's paper and defending it against Edwards' critique. ==References==