In the European Christian tradition from which anthropology emerged the answer was already framed around body and soul. That is what was seen to make them different.
Physical anthropology studies the evolution of the human biological form .
Like other sciences, anthropology accepts Darwinian evolution. It also studies variations and distributions of physical differences in human groups, and the cause and significance of these differences. They look at human populations in terms of gene pools, not cultures. There are just too many cultures and too few races, and the cultural variability within the races is about the same as that between them. No correspondence between the two when one factors out historical cultural contact.