The chronological comparison of languages by comparing their specific basic vocabularies, called lexicostatistics. Since languages theoretically change at a predictable rate, this allows linguists to estimate the time depth between two divergent languages. Hokan A language phylum that may have been a living language during or soon after the Ice Age. Its earliest known territories were in present southern California. It includes, in California, the Achomawi, Atsugewi, Chumash, DigueƱos, Esselen, Pomo, Shastans, Washoe, and Yumans.
Glottochronology is a method in linguistics used to estimate the rate at which languages change, based on the assumption that the basic vocabulary of a language changes at a roughly constant rate. This assumption, originally put forward by Morris Swadesh, is based on an analogy with the use of carbon dating for measuring the age of organic materials, in that a "lexical half-life" is estimated. This is assumed to be the "average" time that any one word is in existence in a particular language.