Language evolution and climate: the case of desiccation and tone

Abstract

We make the case that, contra standard assumption in linguistic theory, the sound systems of human languages are adapted to their environment. While not conclusive, this plausible case rests on several points discussed in this work: First, human behavior is generally adaptive and the assumption that this characteristic does not extend to linguistic structure is empirically unsubstantiated. Second, animal communication systems are well known to be adaptive within species across a variety of phyla and taxa. Third, research in laryngology demonstrates clearly that ambient desiccation impacts the performance of the human vocal cords. The latter point motivates a clear, testable hypothesis with respect to the synchronic global distribution of language types. Fourth, this hypothesis is supported in our own previous work, and here we discuss new approaches being developed to further explore the hypothesis. We conclude by suggesting that the time has come to more substantively examine the possibility that linguistic sound systems are adapted to their physical ecology.

Languages, evolution and statistics: human sound systems were shaped by changes in bite configuration.Response to Tarasov & Uyeda (2020)

“…Lastly, if geographic isolation is taken as a proxy for bottleneck effects, this does not necessarily lead to the loss of phonemes in languages. Clearly, human migration within geographic areas may shape phonological inventories because the sounds of a language are transmitted from parents to children, because languages may come into contact (Thomason 2001) , and because sound systems are affected by various environmental and climatic variables (Everett, Blasi, and Roberts 2016;Dediu, Janssen, and Moisik 2017) , but human expansion out of Africa has left no strong signature on phonological inventories (Creanza et al 2015) .…”

Robust, Causal, and Incremental Approaches to Investigating Linguistic Adaptation

“…The best evidence might come from controlled experiments, but may also include causally informed statistical work or theoretical work. For example, there are several experiments that relate to the causal links between humidity and tone (see Everett et al, 2015 , 2016a ). For example, Hemler et al ( 1997 ) demonstrate that humidity affects vocal fold vibration accuracy.…”

“…This has been done for links between climate and phonetics (see Munroe et al, 2009 ; Maddieson and Coupé, 2015 ). More recently, Everett et al ( 2015 , 2016a ) reviewed research from laryngology showing that dry air affects the vocal folds, making careful control of pitch difficult. There are many cases of animal signals adapting to environmental conditions such as humidity (e.g., Snell-Rood, 2012 ).…”

“…However, most previous analyses in this vein have concentrated on functional pressures from cognition (e.g., Bickel et al, 2015 ), rather than physical pressures from the ambient climate. Accordingly, the link between tone and humidity has been criticized on many grounds, both methodological and theoretical (see Everett et al, 2016a and responses: Collins, 2016 ; de Boer, 2016 ; Donohue, 2016 ; Ember, 2016a ; Gussenhoven, 2016 ; Hammarström, 2016 ; Ladd, 2016 ; Moran, 2016 ; Progovac and Ratliff, 2016 ; Winter and Wedel, 2016 ). The aim of this paper is not to address those criticisms, but to attempt to use this research to illustrate the maximum robustness method.…”

Why Don't Languages Adapt to Their Environment?

“…On the other side of the sandwich, we have a sensorymotor system, which in oral languages corresponds to the vocalauditory system. It is conceivable that certain aspects of the physical environment may bias the kind of sounds most used in some languages (see Everett et al, 2016), but again there would be very limited effects on the morphosyntactic structure of languages.…”