Language is not isolated from its wider environment: Vocal tract influences on the evolution of speech and language

Abstract

Language is not a purely cultural phenomenon somehow isolated from its wider environment, and we may only understand its origins and evolution by seriously considering its embedding in this environment as well as its multimodal nature. By environment here we understand other aspects of culture (such as communication technology, attitudes towards language contact, etc.), of the physical environment (ultraviolet light incidence, air humidity, etc.), and of the biological infrastructure for language and speech. We are specifically concerned in this paper with the latter, in the form of the biases, constraints and affordances that the anatomy and physiology of the vocal tract create on speech and language. In a nutshell, our argument is that (a) there is an under-appreciated amount of inter-individual variation in vocal tract (VT) anatomy and physiology, (b) variation that is non-randomly distributed across populations, and that (c) results in systematic differences in phonetics and phonology between languages. Relevant differences in VT anatomy include the overall shape of the hard palate, the shape of the alveolar ridge, the relationship between the lower and upper jaw, to mention just a few, and our data offer a new way to systematically explore such differences and their potential impact on speech. These differences generate very small biases that nevertheless can be amplified by the repeated use and transmission of language, affecting language diachrony and resulting in cross-linguistic synchronic differences. Moreover, the same type of biases and processes might have played an essential role in the emergence and evolution of language, and might allow us a glimpse into the speech and language of extinct humans by, for example, reconstructing the anatomy of parts of their vocal tract from the fossil record and extrapolating the biases we find in present-day humans

How research on language evolution contributes to linguistics

“…The results of such studies are difficult to interpret in a straightforward way, but they suggest that some cognitive, language-related biases are coded genetically and that these biases can affect the trajectory of language change (cf. Dediu 2008;Dediu et al 2017). As already noted, SLE researchers take a rather broad perspective on how environment impacts language.…”

Experimental Phonetics in Applied Linguistic Research

“…The growing interest to speech implies the development of such a competence in a philologist that would allow him/her to successfully implement a wide range of problems that originate in the sound structure of the language and through it emerge to create communicative tactics and strategies: models of communication, phonetics and presuppositions; phonetics and universal-object code, etc. [Dediu 2017]. …”

Weak biases emerging from vocal tract anatomy shape the repeated transmission of vowels

“…In this model we can precisely control the VT anatomy and observe (and propagate) its effects on the production of actual speech sounds. We concentrate here on one component of the oral VT, the hard palate (HP, which is under genetic and environmental controls, and shows inter-individual and inter-group variation 5,19,22,23 ), and in particular, on the midsagittal hard palate shape (MSHPS; Fig. 1).We use a model of MSHPS we developed previously 19 that allows us to accurately describe the midsagittal shape of any human hard palate (and to generate novel ones) using only four meaningful parameters (angle, fronting, concavity and weight) controlling a customized Bézier curve.…”

“…There are currently about 7,000 spoken languages 3 , an essential aspect of this diversity being represented by their speech sounds (phonetics and phonology). There is wide cross-linguistic variation at this level 4 , and a crucial question concerns the factors and processes driving the emergence and maintenance of this diversity 5 . Most sound changes are due to languageinternal factors, such as co-articulation and misperception 6 , but recent studies suggest that external factors might also generate pressures to which sound systems adapt 5 .…”

“…There is wide cross-linguistic variation at this level 4 , and a crucial question concerns the factors and processes driving the emergence and maintenance of this diversity 5 . Most sound changes are due to languageinternal factors, such as co-articulation and misperception 6 , but recent studies suggest that external factors might also generate pressures to which sound systems adapt 5 . As such, it has been suggested that aspects of the physical environment that vary spatially (e.g., altitude or air humidity) affect the physiology of speech production differently in different populations, resulting in differences between the speech sounds that occur in different languages 5,7,8 .…”