He recognised racial differences as varieties of humanity, and emphasised the close similarities between people of all races in mental faculties, tastes, dispositions and habits, while still contrasting the culture of the "lowest savages" with European civilization. At the end of the 19th century, proponents of scientific racism intertwined themselves with eugenics discourses of "degeneration of the race" and "blood heredity". Henceforth, scientific racist discourses could be defined as the combination of polygenism, unilinealism, social Darwinism, and eugenism. They found their scientific legitimacy on physical anthropology, anthropometry, craniometry, phrenology, physiognomy, and others now discredited disciplines in order to formulate racist prejudices. Before being disqualified in the 20th century by the American school of cultural anthropology (Franz Boas, etc.), the British school of social anthropology (Bronisław Malinowski, Alfred Radcliffe-Brown, etc.), the French school of ethnology (Claude Lévi-Strauss, etc.), as well as the discovery of the neo-Darwinian synthesis, such sciences, in particular anthropometry, were used to deduce behaviours and psychological characteristics from outward, physical appearances. The neo-Darwinian synthesis, first developed in the 1930s, eventually led to a gene-centered view of evolution in the 1960s. According to the Human Genome Project, the most complete mapping of human DNA to date indicates that there is no clear genetic basis to racial groups. While some genes are more common in certain populations, there are no genes that exist in all members of one population and no members of any other. The first theory of eugenics was developed in 1869 by Francis Galton (1822–1911), who used the then-popular concept of "degeneration". He applied statistics to study human differences and the alleged "inheritance of intelligence", foreshadowing future uses of "intelligence testing" by the anthropometry school. Such theories were vividly described by the writer Émile Zola (1840–1902), who started publishing in 1871, a twenty-novel cycle, "Les Rougon-Macquart", where he linked heredity to behavior. Thus, Zola described the high-born Rougons as those involved in politics ("Son Excellence Eugène Rougon") and medicine ("Le Docteur Pascal") and the low-born Macquarts as those fatally falling into alcoholism ("L'Assommoir"), prostitution ("Nana"), and homicide ("La Bête humaine").