Valence-dependent mutation in lexical evolution

A central goal of linguistics is to understand how words evolve over time, and how geographic, demographic, and cognitive variables have influenced this process of evolution. Whereas past research has focused on how macro-level factors like frequency of word usage, population size, and borrowing impact lexical evolution, we draw on insights from cognitive and affective science to test whether the valence (positivity-negativity) of concepts explains variation in rates of lexical evolution. Using estimates of cognate replacement rates for 200 concepts on an Indo-European language tree spanning 6-10 millennia of language evolution, we find that words for negative concepts (e.g., dirty, bad) evolve more quickly than words for positive concepts (e.g., clean, good). In two large online studies, we find that people are more likely to choose to replace words for negative concepts than positive concepts. These effects hold controlling for frequency of use, borrowing, and other semantic properties. Our findings suggest that the valence of concepts affects micro-scale processes of guided variation, which scales up to produce macro-level patterns of lexical evolution. This process informs linguistics research on language change and psychological research on the affective and cognitive properties of lexical semantics.