Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth.Simply, it is also defined as the study of the history of life forms on Earth. Evolution is based on the theory that all species are related and they gradually change over time.

In linguistics, a synchronic analysis is one that views linguistic phenomena only at a given time, usually the present, but a synchronic analysis of a historical language form is also possible. It may be distinguished from diachronic, which regards a phenomenon in terms of developments through time. Diachronic analysis is the main concern of historical linguistics.