The four fields in American anthropology are usually classified as physical, cultural (or ethnology), linguistics and archeology.
Cultural Anthropology deals with the aspects of human lives that are learned. It examines the way different groups keep societal control, delegate responsibilities and other such learned behaviors.
Physical Anthropology studies the way humans have evolved over time and how different environmental and cultural influences affected human evolution.
Archeology is the study of things humans have created in the past.
Linguistics is the study of how languages are formed, evolve and how culture and language interact with each other.
The divisions are made this way for three main reasons. The first is obvious in that it is impossible for a single anthropologist to be well versed in all four at the same time. To the contrary most anthropologists will spend their entire lives studying one small part of one subfield of one of the above main fields. The four groups although they interact and are helpless without each other makes it much easier to determine where and when one group of anthropologists must pass control to another group of specialists.
The second reason is that there are many different ways to study human behavior and one single discipline cannot cover them all. The only real link between linguistics and archeology is that humans created both and both are products of a single culture.
The third reason is the simplistic. Prior to the creation of a “field” of Anthropology the groups already existed as separate disciplines. An archaeologists would receive a degree in archeology; not a degree in anthropology with a specialization in archeology. Still not all scientific cultures agree with this method. Universities in England, for example, still awards degrees specifically in Archeology keeping it separate from Anthropology.
However, there are other classifications that categorize each sub field into either physical or cultural. In this approach the first three items listed below in both Physical and Cultural anthropology are pure research, while the last item in both lists is applied.
- Medical Anthropology