Anthropology is the study of humans and their societies in the past and present. Its main subdivisions are social anthropology and cultural anthropology, which describes the workings of societies around the world, linguistic anthropology, which investigates the influence of language in social life, and biological or physical anthropology, which concerns long-term development of the human organism. Archaeology, which studies past human cultures through investigation of physical evidence, is thought of as a branch of anthropology in the United States, while in Europe, it is viewed as a discipline in its own right, or grouped under other related disciplines such as history.