Historicism is an approach to the study of anthropology and culture that dates back to the mid-nineteenth and early twentieth centuries. It encompasses two distinct forms of historicism: diffusionism and historical particularism.
While socio-cultural evolution offered an explanation of what happened and where, it was unable to describe the particular influences on and processes of cultural change and development. To accomplish this end, an historical approach was needed for the study of culture change and development in order to explain not only what happened and where but also why and how. Diffusionism was the first approach devised to accomplish this type of historical approach to cultural investigation and was represented by two distinct schools of thought: the German school and the British school.
The British school of diffusionism was led by G. E. Smith and included other figures such as W. J. Perry and, for a while, W. H. R. Rivers. These individuals argued that all of culture and civilization was developed only once in ancient Egypt and diffused throughout the rest of the world through migration and colonization. Therefore, all cultures were tied together by this thread of common origin (inferring the psychic unity of mankind) and, as a result, worldwide cultural development could be viewed as a reaction of native cultures to this diffusion of culture from Egypt and could only be understood as such. This school of thought did not hold up long due to its inability to account for independent invention.
The German school, led by Fritz Graebner, developed a more sophisticated historical approach to socio-cultural development. To account for the independent invention of culture elements, the theory of culture circles was utilized. This theory argued that culture traits developed in a few areas of the world and diffused in concentric circles, or culture circles. Thus, worldwide socio-cultural development could be viewed as a function of the interaction of expanding culture circles with native cultures and other culture circles.
American diffusionists believed that people are given to learning and borrowing elements from cultures they come into contact with. As the frequency and duration of contact between two or more cultures increases the likelihood of borrowing and learning from each other also rises. Herskovits – one of the students of Boas, wrote (1955:296) that cultures in an area tended to form clusters that are “sufficiently homogenous that regions on which they occur can be delimited on a map”. Culture area refers to the geographical space in which similar cultures are found. The rationale of the American school of diffusion was that by the mapping spatial distribution of traits in specific geographical areas (i.e., culture areas) it would be possible to explain the similarities and differences between cultures, particularly Native American Cultures. Wissler proposed the age-area hypothesis to explain the relative age of a cultural trait. The age-area hypothesis rests on the assumption that a trait which is more widely distributed around the culture center is older in age than the one which is of limited distribution.
Historical particularism was an approach popularized by Franz Boas as an alternative to the worldwide theories of socio-cultural development as promoted by both evolutionists and extreme diffusionists, which he believed were simply improvable. Boas argued that in order to overcome this, one had to carry out detailed regional studies of individual cultures to discover the distribution of culture traits and to understand the individual processes of culture change at work. In short, Boas sought to reconstruct the histories of cultures. He stressed the meticulous collection and organization of ethnographic data on all aspects of many different human societies. Only after information on the particulars of many different cultures had been gathered could generalizations about cultural development be made with any expectation of accuracy.(source:books)