Automated Dating of the World’s Language Families Based on Lexical Similarity

Abstract

This paper describes a computerized alternative to glottochronology for estimating elapsed time since parent languages diverged into daughter languages. The method, developed by the Automated Similarity Judgment Program (ASJP) consortium, is different from glottochronology in four major respects: (1) it is automated and thus is more objective, (2) it applies a uniform analytical approach to a single database of worldwide languages, (3) it is based on lexical similarity as determined from Levenshtein (edit) distances rather than on cognate percentages, and (4) it provides a formula for date calculation that mathematically recognizes the lexical heterogeneity of individual languages, including parent languages just before their breakup into daughter languages. Automated judgments of lexical similarity for groups of related languages are calibrated with historical, epigraphic, and archaeological divergence dates for 52 language groups. The discrepancies between estimated and calibration dates are found to be on average 29% as large as the estimated dates themselves, a figure that does not differ significantly among language families. As a resource for further research that may require dates of known level of accuracy, we offer a list of ASJP time depths for nearly all the world's recognized language families and for many subfamilies. The greater the degree of linguistic differentiation within a stock, the greater is the period of time that must be assumed for the development of such differentiations.

Universals versus historical contingencies in lexical evolution

“…The specificity and historically contingent nature of lexical change seemingly contradict observations regarding regularities underlying lexical change which cut across languages and time periods, i.e. universals of lexical change [1,2,9,10,17,18,24]. The contradiction, however, is only apparent, because the points of view are distinct.…”

“…But, such studies raise the question of whether the rate of change might still be sufficiently constant that it is useful for dating language group divergence with reasonable accuracy provided that averages over several languages are used and the time spans measured are great enough. A recent study from the project known as the Automated Similarity Judgment Program (ASJP) [9] uses a measure of phonological distance between words as another way of deriving dates of language group divergence. Glottochronology uses a count of cognates (related words) as its input.…”

“…Thus, the ASJP approach is also sensitive to cognacy and therefore comparable to glottochronology. It was found in reference [9] that for 52 groups of languages whose divergence dates are approximately known, there is a -0.84 correlation between log similarity and time. Thus, the assumption of glottochronology of an approximately regular rate of change is vindicated in this study, which is the first to provide a test across many language groups.…”

Multiple lines of evidence for the origin of domesticated chili pepper,Capsicum annuum, in Mexico

“…Brown (22) surveyed the reconstructed vocabularies of 30 protolanguages of Mesoamerica (southern half of Mexico and northern Central America) and abutting areas for terms for 41 different crops, including chili pepper. His survey presented for each protolanguage the estimated date it was spoken at the latest, making it possible to stratify reconstructed words for crops chronologically (Table 1) (27,28).…”

“…The presence of words for a species in an ancestral language is an indication of the species' significance to speakers of that language (25,26), if not their status as domesticated plants. PBL uses Automated Similarity Judgment Program (ASJP) chronology for estimating the latest date at which a protolanguage was spoken based on lexical similarity (27). Lexical similarity found among related languages is calibrated with historical, epigraphic, and archaeological divergence dates for 52 language groups.…”