While it is closely related to sociology, cultural anthropology differs in that the groups under study are usually non-Western. Theories about the world that are based on assumptions and values of one's own culture. Archaeology is not limited, like history, to the written records of the last 5000 years, but can go back as far as 2.5 million years. Conversely, it can investigate modern issues as garbage studies demonstrate. Forensic archaeology is also an integral part of forensic anthropological investigations.
Linguistic anthropology studies human language.
While some animals, like the apes, possess sounds and gestures that serve functions comparable to speech, no animal system of symbolic communication is so complex as that of humans. Language can show what is important in a culture. Ethnology seeks to offer a systematic firsthand description of a culture. The culture is studied through participant observation , in which the researcher learns about the culture by living in it for an extended period. This approach is termed the holistic perspective .