手法を比較

	Phylogenetic Linguistics	Glottochronology (Lexical Dating)
分野	言語学	言語学
系統	Process / pipeline	Process / pipeline
提唱年	2003	1952
提唱者	Russell Gray & Quentin Atkinson (modern Bayesian application); rooted in computational phylogenetics	Morris Swadesh
種類	Computational inference of language family trees and divergence dates from coded linguistic data	Estimation of time depth of language separation from cognate retention
原典	Gray, R. D., & Atkinson, Q. D. (2003). Language-tree divergence times support the Anatolian theory of Indo-European origin. Nature, 426(6965), 435–439.	Swadesh, M. (1955). Towards greater accuracy in lexicostatistic dating. International Journal of American Linguistics, 21(2), 121–137.
別名	Linguistic Phylogenetics, Computational Language Phylogenetics, Phylogenetic Language Classification	Glottochronology, Lexicostatistic Dating, Linguistic Dating
関連	4	4
概要	Computational phylogenetic linguistics borrows the statistical machinery developed in evolutionary biology — Bayesian inference, maximum likelihood, and distance-based network methods — and applies it to coded linguistic data, chiefly cognate-judged basic vocabulary, to infer language family trees and estimate when branches diverged. By treating linguistic characters like the molecular characters in a gene alignment and modelling their change probabilistically along a tree, the approach produces classifications with explicit measures of uncertainty and, when calibrated, dated phylogenies. Its best-known applications are the Gray and Atkinson and Bouckaert et al. analyses of Indo-European origins.	Glottochronology is Morris Swadesh's method for estimating the time depth at which two related languages separated, derived from the proportion of basic-vocabulary cognates they still share. Building directly on lexicostatistics, it adds a crucial extra assumption — a 'glottoclock' — that basic vocabulary is lost at an approximately constant rate over time, analogous to radioactive decay. Plugging the observed cognate proportion into a logarithmic decay formula yields an estimated separation date in years. The method is historically important but has been heavily criticized, and most historical linguists today treat its dates with great caution.