The author investigates whether geographic factors--namely high elevation or 1500 m+ above sea level (reduced atmospheric pressure)-- impact the production, use, and ubiquity of ejective phonemes in eight non-contiguous language clusters. It is suggested that increased use of ejective phonemes has a physiological benefit: the reduction of water vapor loss via exhaled air. Evidence is presented in support of the hypothesized geographic-phonetic linkage.

Utilizing two independently-coded databases representing 3700+ languages, authors investigate whether cold ecologies or otherwise-desiccated ecologies are less amenable to complex tonality in language. Languages with complex tonality are primarily found to be located in tropical regions and generally absent in desiccated environments, regardless of latitude.

This study sampled over 4,012 language varieties, comparing their version of 40 generally universal words, such as body parts, water, the sun, pronouns, and common behaviors or animals. These language variations were tested in their association to "specific humidity," the variable used to represent ambient humidity of a language location. Results suggest negative association between the dryness of climate and the utilization of vowels, consitent with the idea that dry air affects the behavior of the larynx.