An analysis of language from around the world suggests that human speech originated—just once—in central and southern Africa. This verbal communication then likely spread around the globe, evolving alongside migrating human populations, according to the new research.
A comprehensive study of phonemes, or the perceptually distinct units of sound that differentiate words, used in 504 human languages today revealed that the dialects containing the most phonemes are spoken in Africa. Those with the fewest phonemes are spoken in South America and on tropical islands in the Pacific Ocean.
The analysis, reported in the 15 April issue of Science, finds that this pattern of phoneme usage around the world mirrors the pattern of human genetic diversity, which also declined as humans expanded their range from Africa to colonize other regions.
Quentin Atkinson from the University of Auckland in New Zealand compiled data on vowel, consonant, and tone inventories from the World Atlas of Language Structures—a large dataset of the structural properties of languages—and considered them in the context of modern language location, taxonomic affiliation, and speaker demography. The picture that emerged reveals an exodus of language from the African continent to other areas of the world.
“Just as geneticists see a decline in genetic diversity, with such diversity decreasing as you move away from Africa, language diversity shows a similar decline,” Atkinson said. “It seems like the obvious explanation is that people carried language—along with their genes—with them as they expanded out of Africa.”
In general, the areas of the globe that were most recently colonized incorporate fewer phonemes into the local languages. On the other hand, regions that have hosted human life for millennia (particularly sub-Saharan Africa) still use the most phonemes.
Outside Africa, the highest levels of phonemic diversity are found in language families associated with the indigenous people of Southeast Asia. This detail also agrees with genetic evidence indicating that Southeast Asia experienced a major migration of modern humans from Africa about 50,000 to 70,000 years ago.
Atkinson says that this decline in phoneme usage moving away from Africa cannot be explained by demographic shifts or other local factors, and it provides strong evidence for an African origin of modern human languages—as well as parallel mechanisms that slowly shaped both genetic and linguistic diversity among modern humans.
His study frames complex language as one of the earliest archaeological symbols of modern human culture, suggesting that it was a key cultural innovation that ultimately led to our colonization of the globe.
“Modern humans are just one big, genetic family with a single common ancestor,” Atkinson said. “One of the things I like about these results is that, to the extent that language is an identity, we all seem to be part of one big, cultural family as well.”
Read the report, “Phonemic Diversity Supports Serial Founder Effect Model of Language Expansion from Africa,” by Quentin Atkinson.