Clever Study Uses Genetics Trick to Trace Language Back to Its Very Beginning, in Africa

one...two...tree · April 16, 2011

What’s the News: Southern Africa may be the birthplace of human language, according a new study published yesterday in Science. The study further suggests that language may have arisen only once, with one ancestral language giving rise to all modern tongues, an idea linguists have long debated. This finding parallels the human migrations out of Africa supported by genetic and fossil evidence.

How the Heck:

The study’s author, evolutionary psychologist Quentin Atkinson of the University of Auckland in New Zealand, looked at 504 modern languages from around the world.
He then tallied the phonemes—the distinct sounds of consonants, vowels and tones—that make up each language. Languages vary widely in how many phonemes they have: Some of the Khoisan languages in Africa (widely known for their click sounds) have more than a hundred phonemes, while languages spoken in many Pacific islands have far fewer, such as Hawaiian’s 13. (English is somewhere in the middle, with about 45.)
To build a model for the origins of language, Atkinson borrowed an idea from population genetics: the founder effect, which says that when a small group branches off from a population, it loses genetic diversity.
Performing mathematical analysis to bring together the number of phonemes a language had and its location on the globe, Atkinson found a linguistic founder effect: The farther from Africa, the fewer phonemes a language had—the less diverse its sounds were. This distance from Africa explained 30% of the variation in number of phonemes a language had, and still explained nearly 20% of the variation when modern population size was taken into account (since smaller populations are also linked to a smaller number of phonemes).

What’s the Context:

Language is believed to be at least 50,000 years old, and could be 100,000 years old, predating the human migrations out of Africa that began about 50,000 years ago. The development of language in Africa, Atkinson told the Wall Street Journal, “was the catalyst that spurred the human expansion that we all are a product of.”
Using the traditional methods of tracking how words evolve, linguists have only been able to trace particular languages back less than 10,000 years, since words change so quickly (and there are no written records going back further). By taking a different approach, Atkinson may have gleaned information about language much further back in time.

Not So Fast:

While Atkinson’s idea stems from population genetics, the mechanisms of change in the two fields are very different: A population’s genetic diversity changes over generations, while phonemes can change far more rapidly. The founder effect accounts for a different amount of the variation between groups, as well, explaining up to 85% of the genetic diversity in populations but only about 20% of the phoneme diversity in languages.
Many linguists aren’t yet sure if they should believe what they hear. As University of Pennsylvania linguist Donald A. Ringe told the New York Times, “It’s too early to tell if Atkinson’s idea is correct, but if so, it’s one of the most interesting articles in historical linguistics that I’ve seen in a decade.”

Reference: Quentin D. Atkinson. “Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa,” Science, April 15, 2011. DOI:10.1126/science.1199295

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