In linguistics, the technique of glottochronology is used to estimate the time of divergence of two related languages. It is analogous to the use of C14 dating for measuring the age of organic materials, in that a "lexical half-life" is estimated and used to extrapolate to the point in time at which a given two languages diverged from a common proto-language.

The method presumes that the basic vocabulary may be used as a sort of clock, on the assumption that basic vocabulary changes at a more-or-less constant rate through time. The process makes use of the Swadesh list, a list of basic lexical terms compiled by Morris Swadesh. This core vocabulary was designed to encompass concepts common to every human language, eliminating concepts that vary by culture and time.

Glottochronology is highly controversial, as many linguists argue that there is no substantial evidence that language change occurs at a steady rate. For instance, there is evidence that unwritten languages tend to change more rapidly than written ones, and many linguists therefore regard the method as invalid, or at least view glottochronological data with strong scepticism.

Lexicostatistics involves measuring the percentage of cognates (words that have a common origin) in "basic word lists". The larger the percentage of cognates, the more recently the two languages being compared are presumed to have separated.

Bibliography

• Robert Lees (1953), The Basis of Glottochronology, Language, Vol. 29, No. 2., pp. 113-127.
• John McWhorter (2001), The Power of Babel. New York: Freeman. ISBN 0-7167-4473-2.
• Andree Sjoberg and Gideon Sjoberg (1956), Problems in Glottochronology, American Anthropologist , New Series, Vol. 58, No. 2., pp. 296-308.

External link

• Swadesh list in Wiktionary.
• Discussion with some statistics
• Indo-European lexicostatistical data