December 12, 2003

Good glottochronology

Again and again, the world is presented with another example of the same old drama: a fascinating hypothesis about deep history is bravely advanced and defended by a few methodologically adventurous souls, who come under relentless attack from a posse of hidebound linguistic nay-sayers firing footnotes from their hiding places in the library stacks.

At least that's how some people seem to see the story. The facts, as usual, are more complex and more interesting, even when it's biologists as hypothesizers and linguists as critics. See the recent Language Log posts about Forster and Toth here, and Gray and Atkinson here, here, and here.

Well, this is how science is supposed to work: hypotheses have to be criticized and defended, not just appreciated, for genuine knowledge to advance. But the story is misleading: in fact linguists are far more likely to be intrepid hypothesizers than critical snipers, whether the subject is deep history or social dynamics or epistemology. And I might also need to point out that linguists as a class are unusually open to the interdisciplinary trade in ideas, both as importers and as exporters.

In particular, it's not as well known as it should be that some ethnohistorians routinely use a variety of linguistic methods, including lexicostatistics and glottochronology, and that professional linguists by and large approve and even collaborate.

Edda Fields' dissertation on Rice Farmers in the Rio Nunez Region works out the history and chronology for the migration of various ethnic groups and the development of wet rice cultivation in the mangrove swamps of coastal Guinea, during a period from roughly 2000 BCE to 1880 CE. Edda uses all available sources of evidence, but in this case, much of the evidence turns out to be linguistic. As she writes, "[i]n coastal Guinea, ... [t]here is no viable method for dating oral narratives .. [a]nd ... there is no other historical data that pre-dates the 15th century Portuguese accounts." She also faced current "absence of direct carbon, pollen, climate change and archeological evidence for the early history of the Rio Nunez region." As one method to find historical patterns, she examines the vocabulary associated with the material culture of rice farming, looking to see which languages borrowed terms from which other languages, as evidence about the sources of various innovations. In order to assign dates, classical glottochronology (based to a large extent on word lists she gathered herself in the field) was her main tool. Are the resulting estimated dates exact? Certainly not. Are the estimates worth having? Absolutely.

I think this is terrific work, and would argue that its application of lexicostatistics and glottochronology is entirely appropriate, given the usual caveats about interpretation of the results (which Edda is careful to express).

I should also mention that this work has a vital connection to American history, because of the key role of West African slaves in adapting their wet rice farming methods to the plantations of coastal Carolina in the late 17th century. These were the first commercially successful plantations on the North American mainland, and played a significant role in the early economic development of the British colonies here.

Posted by Mark Liberman at December 12, 2003 08:40 AM