Genes, language, and how we study human pre-history


The Wall Street Journal has a story out today about a study published in the journal Science that claims all modern languages evolved out of the same proto-language—the linguistic version of Out-of-Africa. Meanwhile, the BBC is reporting on a paper published in Nature which suggests features that are shared between languages actually evolved independently, rather than being concepts coded into our brains by biology.

I'm not sure whether these two sets of results can be easily compared to one another. The studies were aimed at answering very different questions, so you can't just line one up against the other. Depending on your point of view, these results may be contradictory … but that's not necessarily the case. What I do think is interesting about these two studies is the fact that both are based on research methodologies and theories that were born in the fields of evolutionary biology and genetic anthropology. For instance, the Wall Street Journal article says:

His research is based on phonemes, distinct units of sound such as vowels, consonants and tones, and an idea borrowed from population genetics known as "the founder effect." That principle holds that when a very small number of individuals break off from a larger population, there is a gradual loss of genetic variation and complexity in the breakaway group. Dr. Atkinson figured that if a similar founder effect could be discerned in phonemes, it would support the idea that modern verbal communication originated on that continent and only then expanded elsewhere.

And in the BBC story:

Lead author Michael Dunn, an evolutionary linguist at the Max Planck Institute for Psycholinguistics in the Netherlands, said the approach is akin to the study of pea plants by Gregor Mendel, which ultimately led to the idea of heritability of traits. Modern phylogenetics studies look at variations in animals that are known to be related, and from those can work out when specific structures evolved. For their [linguistic] studies, the team studied the characteristics of word order in four language families: Indo-European, Uto-Aztec, Bantu and Austronesian.

I'm curious how widespread this interdisciplinary approach is within linguistics, and whether most linguists think it's a reasonable way to study language evolution. I would think, at the very least, that you have to make some adjustments. After all, as the Wall Street Journal article points out, the forces that shape biological evolution work differently from those that shape cultural evolution.

Dr. Atkinson's approach has its limits. Genes change slowly, over many generations, while the diversity of phonemes amid a population group can change rapidly as language evolves. While distance from Africa can explain as much as 85% of the genetic diversity of populations, a similar distance measurement can explain only 19% of the variation in phonemic diversity. Dr. Atkinson said the measure is still statistically significant.

Wall Street Journal: The Mother of All Languages

BBC: Language Universality Idea Tested with Biology Method

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