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

Bibliographic Collection: 
Publication Type: Journal Article
Authors: Everett, Caleb; Blasi, Damián E; Roberts, Seán G
Year of Publication: 2015
Journal: Proc Natl Acad Sci U S A
Volume: 112
Issue: 5
Pagination: 1322-7
Date Published: 2015 Feb 3
Publication Language: eng
ISSN: 1091-6490

We summarize a number of findings in laryngology demonstrating that perturbations of phonation, including increased jitter and shimmer, are associated with desiccated ambient air. We predict that, given the relative imprecision of vocal fold vibration in desiccated versus humid contexts, arid and cold ecologies should be less amenable, when contrasted to warm and humid ecologies, to the development of languages with phonemic tone, especially complex tone. This prediction is supported by data from two large independently coded databases representing 3,700+ languages. Languages with complex tonality have generally not developed in very cold or otherwise desiccated climates, in accordance with the physiologically based predictions. The predicted global geographic-linguistic association is shown to operate within continents, within major language families, and across language isolates. Our results offer evidence that human sound systems are influenced by environmental factors.

DOI: 10.1073/pnas.1417413112
Alternate Journal: Proc. Natl. Acad. Sci. U.S.A.