In the early 1950s, geneticists and physical anthropologists recognized their professional dilemma. On the one hand, they still found it important to study human biological variation empirically, and even more so in the light of the new evolutionary synthesis. On the other hand, "race," the term that had prevailed until then in political and scientific debates, now provoked nothing but suspicion and criticism from other scholars and the public. The scientists met this challenge by activities on the political level, by discussing the issues at stake within the scientific community and by empirical work.
Historians have already taken notice of the first two kinds of activities in the last decade. In several UNESCO initiatives and statements, and accompanied by a number of popular publications, scientists from a variety of disciplines took a decidedly anti-racist stance. At the same time, they advanced internal debates on methodological and conceptual issues. In contrast to their discourse oriented approach, this project concentrated on the empirical work of the same geneticists and physical anthropologists in the 1950s and 1960s.
In general, historians have noted a shift from notions of "race" to notions of "population" after World War II, along with methodological shifts from anthropometric to serological and later to molecular methods. But these shifts did not take place all at once; it was quite a complex process that led to conceptual inconsistencies on the side of the scientists. Lisa Gannett has argued that "race" was by no means replaced by population, but that the typological race concept was transformed into a concept of population that was supposed to be grounded in statistics. Other accounts show that scientists began to conceive of human diversity as structured in clines (instead of few, easily distinguishable races) not before 1962. In the previous decade, physical anthropologists, human geneticists, and serologists struggled to claim their respective discipline and its methods as the best way to explore human diversity. From the establishment of racial anthropology in the 1920s up to the 1960s, serology enjoyed the status of an objective way to study human races, but it could be employed for very different ends.
While racial concepts were not abandoned—contrary to what some historians have suggested—the attention of geneticists, like Dobzhansky and Dunn, shifted to problems of human evolution and genetics (selection, isolation, mixing, migration, drift, and so forth). Their empirical work, and what it reveals about practices and understandings of human diversity at the time, was at the center of this project. It was also contextualized within a broader history of diversity studies, racial serology, and human genetics in the twentieth century, which has recently gained new attention with the Human Genome Diversity Project.
In contrast to the political and scientific debates, and in contrast to the national concerns that historians have used thus far, investigations of human biological diversity did not only take place in the US, Germany or elsewhere in the Western world. To a large extent, human diversity research has been pursued in colonial and postcolonial contexts or in other politically explosive circumstances, where scientists hoped to find "isolated" or "mixed" groups that could be studied under clearly defined conditions. For example, in 1954 geneticist Leslie C. Dunn examined the “Jewish community” of Rome as an example for an inbreeding population. At the same time, colleagues viewed the caste system in India as “the largest biological experiment ever” for human geneticists to study. Investigating human biological diversity was not a laboratory endeavor: it required social interaction and confronted scientists with tensions between minorities and majorities. The project therefore contextualized their work within the contemporary political situation and analyzed the biohistorical narratives that the respective actors employed on the spot to force their point.