Structural linguistic diversity and human genetic diversity are inversely correlated

What is it about?

Languages are diverse: thousands are spoken worldwide, and they differ widely in the structures they use, for example in the word orders they use. Human DNA variation preserves the history of populations and individuals. This paper assesses whether and how these two dimensions of human diversity are related? Does the diversity of languages correlate with the diversity of their speakers? The answer is yes, but not in the way one might expect. Regions with low genetic diversity across speakers show languages with high diversity, and vice versa. In other words, the more diverse our DNA, the more similarly we speak!

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Photo by Issa K_T on Unsplash

Photo by Issa K_T on Unsplash

Why is it important?

The relationship between the diversity and history of human populations and their languages have captured the interest of scientists and the public for over a century. This paper combines new large-scale genetic and linguistic datasets with global coverage to analyse how genetic variation across individuals relates to structural variation across languages within each region. Adjusting for other possible influences like geographic proximity, population density and environmental factors, thereby allows to truly isolate the role of demographic history on shaping landscapes of linguistic diversity. The result is a clear global signal: the same forces that shape the genetics of human populations – contact, migration and isolation – also shape the diversity of language structures, but in opposite ways: Contact increases genetic diversity, but it also promotes the spread of linguistic features, making languages more similar. Isolation, by contrast, limits genetic diversity while allowing languages to evolve independently. This dynamic helps explain why some regions of the world stand out as hotspots of linguistic diversity. Areas such as New Guinea or the Himalayas are genetically relatively isolated; at the same time their languages are hotspots of diversity. Such hotspots give us a glimpse of what languages can do when evolving under conditions of relative isolation: They preserve a wider range of ways of organizing grammar, sound and meaning, a range that cannot be observed elsewhere because it got reduced by long histories of contact. Beyond documenting a striking global pattern, the study highlights a broader implication: linguistic diversity is deeply intertwined with human history.

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