Two professors of Linguistics have identified the "primal consonants" of human languages  ̶ a small set of five consonant types that most likely were the original consonant sounds in early, even pre-human, communication, and subsequently underwent change to form the modern-day inventory of 500 to 600 different consonants found in languages across the globe.

Distinguished Professor Emerita of Linguistics Joan Bybee from The University of New Mexico and University of Hawai'i Mānoa assistant professor of Linguistics Shelece Easterday, who completed her graduate studies at UNM, recently published their findings in a new article in the international journal Language Dynamics and Change.

Two age-old questions about the nature of human language are: Where does it come from? And how did it become the way it is? This research is a contribution to understanding the larger story of how human language could have evolved, Bybee said.

Bybee explained that the proposed primal consonants come from five sets: the stops made with full closure of the lips (labials), /p b m/; stops made with the tongue creating closure at the teeth or behind the teeth, /t d n/; stops made with the back of the tongue against the soft palate, /k g ŋ/; and two others, fricative /s/ and lateral /l/.

“Almost all languages use consonants from these five sets to make words,” she said. “Research on 81 unrelated languages identified sound changes that this small set of consonants undergoes to create new consonants… By contrast, it is very rare for consonants not included in the primal consonant set to change into one of the primal consonants. The discovery of these primal consonants is a major contribution to our understanding of the origins of human language.”

Over several years, Bybee and Easterday combed through descriptions of the sounds in 81 different languages from all over the world and created a database of all the changes that affect them ̶ for example, /t/ in the words water, attic, and pattern is very d-like. Then to conduct the research for this paper, they counted up all the changes that affect consonants and what consonants result from those changes.

“Words can stay in a language a long time, and preserve the same sounds over many generations of speakers,” Bybee explained. “The sounds can change gradually, but these changes are usually very systematic. If we compare the Germanic words exemplified by English father, foot, fish to the Romance words meaning the same thing, Latin pater, ped, pesc, we see that words in Latin that begin with /p/ in English begin with /f/. If we consult Sanskrit as well, we see that the /p/ is original and the /f/ occurs only in Germanic. So the ancestor of these languages ̶ Proto-Indo-European ̶ had a /p/ in these words. If such comparisons are carried out extensively, we have a good idea of how ancient languages were pronounced.”