Softer, processed foods changed the way ancient humans spoke

The human capacity for language divides our species from the rest of the animal kingdom. Language has not only allowed us to conquer all corners of the globe, but to devise writing, mathematics and all things thereafter.

But researchers can find many of language’s basic design features in the communication systems of other animals. For example, many animals have particular calls for specific objects and meanings, and some even seem to combine calls in meaningful, albeit rudimentary ways. These lines of continuity, however thin, drive home the point that, at its essence, language is part of our biology.

Our new research suggests that a biological perspective is indeed necessary to resolve why languages have the range of sounds they have. We draw on evidence from paleoanthropology, speech biomechanics, ethnography and historical linguistics to suggest that new speech sounds emerged in our ancient ancestors as their jaws and teeth evolved to deal with new kinds of diets.

Biology and language

To study the origins of language and understand how it evolved into the remarkable faculty that we have today, it makes sense to investigate language from a perspective that includes biology as well as culture. But language doesn’t figure into the typical biology curriculum. It’s mostly considered a purely intellectual and cultural phenomenon, grouped together with literature and art as part of the humanities.

But this categorization is peculiar because, like the communication systems of other animals, language is simply part of our nature. We process it with the neural wiring in our brains, and we produce it with our bodies: mostly with our mouths, but in the case of sign languages, also with our hands and other gestures.

Language is also often seen as a fixed skill – it arose with the emergence of our species and has been stable in its basic design since its origin.

This traditional view is part of what researchers call the uniformitarian assumption in linguistics and anthropology. The assumption is that languages today are the same – in terms of their types and distributions of linguistic structures – as they were in the past.

Food and language

Our research group’s work directly challenges this uniformitarian assumption. We believe the range of available speech sounds used in human language has not remained stable since its origin. Our research shows that labiodental sounds – such as “f” and “v,” which are made by raising the bottom lip to the upper teeth – began to arise only after the transition to agriculture, between 10,000 and 4,000 years ago (depending on the world region).

While labiodentals are rather common today and appear in roughly half of the world’s languages, we show that in the case of Indo-European languages, they’ve been innovated mainly since the Bronze Age.

Why? What caused this sudden emergence of a new class of speech sounds?