Lexicostatistics

Lexicostatistics is a methodological approach used in historical linguistics to estimate the degree of relatedness among languages and to reconstruct aspects of language evolution. It involves the systematic comparison of a standardized set of core vocabulary—often called a "swadesh list"—across different languages to determine the proportion of shared cognates. This percentage of shared vocabulary provides an approximate measure of how closely related the languages are and can aid in establishing language family trees.

The primary assumption underpinning lexicostatistics is that the rate of lexical replacement is relatively constant over time. By calculating the percentage of cognates retained between languages, linguists can estimate the time since the languages diverged from a common ancestor, a process known as glottochronology. However, the method's accuracy is subject to debate due to variations in vocabulary replacement rates and the influence of borrowing, which can distort true genetic relationships.

First introduced by Morris Swadesh in the mid-20th century, lexicostatistics aimed to provide a quantitative framework for linguistic subgrouping. Despite criticisms regarding its assumptions and limitations, it remains a useful tool for initial language classification and for informing more detailed historical linguistic analyses.

Today, lexicostatistics is often complemented by other methods such as phonological, grammatical, and computational approaches, which help provide a more comprehensive understanding of linguistic histories. While no longer regarded as definitive for dating language splits, lexicostatistics continues to contribute to the study of language relationships and evolution.