Climate, vocal folds, and tonal languages: Connecting the physiological and geographic dots

TLDR

The sound systems of human languages are not generally thought to be ecologically adaptive. The study provides extensive evidence that language sound systems are ecologically adaptive and influenced by climate. Using laryngology data showing aridity impairs vocal cord movement, the authors predict complex tone patterns are unlikely to evolve in arid climates. Statistical sampling of climatic and phonological data for over half of the world’s languages supports this prediction, concluding that human sound systems are influenced by environmental variables.

Abstract

Significance The sound systems of human languages are not generally thought to be ecologically adaptive. We offer the most extensive evidence to date that such systems are in fact adaptive and can be influenced, at least in some respects, by climatic factors. Based on a survey of laryngology data demonstrating the deleterious effects of aridity on vocal cord movement, we predict that complex tone patterns should be relatively unlikely to evolve in arid climates. This prediction is supported by careful statistical sampling of climatic and phonological data pertaining to over half of the world’s languages. We conclude that human sound systems, like those of some other species, are influenced by environmental variables.