The American cultural anthropologists also have not been able to contribute much to the theoretical stock of anthropology.
Whatever little theoretical contribution that we find in anthropology is through the development of theories on culture growth. There are several theories which explain the diffusion and spread of culture traits. Culture, as we find it today, has not grown or developed overnight.
It has taken thousands of years. From Cro-Magnon man to the present man millions of years have passed. Each generation has contributed something to the stock of culture. Culture processes, all through history, have contributed to the development of culture.
Systematic investigation of the problem of cultural transmission or cultural borrowing dates from about the beginning of the 20th century. In other words, the culture growth theories have taken about hundred years in their construction.
Before that only ethnographic data were generated. Whatever theories of culture growth we find today may be divided into three classes as under:
(1) Pan-Egyptian or Heliolithic Theory
(2) German-Austrian Culture Historical Theory
(3) Functional Theory
We now proceed to these theories in some details. The idiom of these theories is diffusion. In other words, culture growth all over the world has been explained with reference to culture diffusion.