and Georg Forster, and in France by Julien-Joseph Virey. In the US, Samuel George Morton, Josiah Nott and Louis Agassiz promoted this theory in the mid-19th century. Polygenism was popular and most widespread in the 19th century, culminating in the founding of the Anthropological Society of London (1863), which, during the period of the American Civil War, broke away from the Ethnological Society of London and its monogenic stance, their underlined difference lying, relevantly, in the so-called "Negro question": a substantial racist view by the former, and a more liberal view on race by the latter. Modern scholarship Models of human evolution Today, all humans are classified as belonging to the species Homo sapiens. However, this is not the first species of homininae: the first species of genus Homo, Homo habilis, evolved in East Africa at least 2 million years ago, and members of this species populated different parts of Africa in a relatively short time. Homo erectus evolved more than 1.8 million years ago, and by 1.5 million years ago had spread throughout Europe and Asia. Virtually all physical anthropologists agree that Archaic Homo sapiens (A group including the possible species H. heidelbergensis, H. rhodesiensis and H. neanderthalensis) evolved out of African Homo erectus (sensu lato) or Homo ergaster. Anthropologists support the idea that anatomically modern humans (Homo sapiens) evolved in North or East Africa from an archaic human species such as H. heidelbergensis and then migrated out of Africa, mixing with and replacing H. heidelbergensis and H. neanderthalensis populations throughout Europe and Asia, and H. rhodesiensis populations in Sub-Saharan Africa (a combination of the Out of Africa and Multiregional models). Biological classification In the early 20th century, many anthropologists taught that race was an entirely biological phenomenon and that this was core to a person's behavior and identity, a position commonly called racial essentialism. This, coupled with a belief that linguistic, cultural, and social groups fundamentally existed along racial lines, formed the basis of what is now called scientific racism. After the Nazi eugenics program, along with the rise of anti-colonial movements, racial essentialism lost widespread popularity. New studies of culture and the fledgling field of population genetics undermined the scientific standing of racial essentialism, leading race anthropologists to revise their conclusions about the sources of phenotypic variation. A significant number of modern anthropologists and biologists in the West came to view race as an invalid genetic or