The origins of language are shrouded in mystery, with linguists unable to probe beyond about 10,000 years ago. But a radical new study reveals language sounds spread just like human genes, suggesting Africa was the sole birthplace of language.
Historical linguistics has been able to pull off some absolutely incredible feats of language reconstruction - perhaps most famously linking together many of the languages of Europe with those of central Asia to reveal the Indo-European language family - but its range is limited to "only" about 10,000 years ago. With no recorded evidence of what languages sounded like before that, there's no way to know whether the various huge language families all developed independently out of the proto-language of early humans, or whether humanity ever had something akin to a single common language.
Now University of Auckland researcher Quentin Atkinson has found some evidence that might support the latter possibility. He considered phonemes, which are the individual sounds that make up language and allow us to distinguish different words, and charted their distribution throughout 504 languages all over the world. He found conclusively that there is much greater phoneme diversity in Africa, while South America and Oceania have the smallest phonemic diversity.
Intriguingly, this is a near perfect match for how genetic diversity spreads out across the globe, with Africa, the birthplace of humanity, having the highest diversity while those areas that were settled last by humans have the least. With genetics, this is usually attributed to what's known as the founder effect, in that human migration requires a smaller population to leave the original, thus reducing the genetic diversity of the breakaway group.
As Atkinson explains in his paper, published today in Science, the same founder effect could operate with phonemes and, by extension, language itself:
If phoneme distinctions are more likely to be lost in small founder populations, then a succession of founder events during range expansion should progressively reduce phonemic diversity with increasing distance from the point of origin, paralleling the serial founder effect observed in population genetics. A founder effect has already been used to explain patterns of variation in other cultural replicators, including human material culture and birdsong. A range of possible mechanisms predicts similar dynamics governing the evolution of phonemes and language generally. This raises the possibility that the serial founder-effect model used to trace our genetic origins to a recent expansion from Africa could also be applied to global phonemic diversity to investigate the origin and expansion of modern human languages.
The fact that phoneme diversity consistently decreases the further you get from Africa is intriguing evidence that language really was only developed once, and this occurred long before humanity left Africa. After all, if language was developed in multiple independent events, then there should be multiple areas with high phoneme diversity, but that just is what the data shows.
Indeed, Atkinson doesn't just suggest that language predated humanity colonizing the planet - it might actually have helped power the migrations:
To the extent that language can be taken as an example of cultural evolution more generally, these findings support the proposal that a cultural founder effect operated during our colonization of the globe, potentially limiting the size and cultural complexity of societies at the vanguard of the human expansion. An origin of modern languages predating the African exodus 50,000 to 70,000 years ago puts complex language alongside the earliest archaeological evidence of symbolic culture in Africa 80,000 to 160,000 years ago. Truly modern language, akin to languages spoken today, may thus have been the key cultural innovation that allowed the emergence of these and other hallmarks of behavioral modernity and ultimately led to our colonization of the globe.
It's worth stressing that, while this does support a single origin for language in either central or southern Africa, this definitely doesn't get us any closer to knowing what that language sounded like. To do that, we would need to have some means to reconstruct it back to 50,000 or 100,000 years ago. Considering language reconstruction techniques can't get us back much further than about 6,500 years ago, the original language of humanity most likely must remain lost in the mists of prehistory.