Walnut trees linked with development of language, trade routes

WEST LAFAYETTE, Ind., Sept. 4 (UPI) -- What do walnuts have in common with the earliest human languages and the first trade routes? A lot, according to scientists at Purdue University.

When you map the evolution of language and the evolution of the walnut tree, you find a wide overlap stretching across much of Eurasia. These overlaps highlight the routes of early spice traders who, traveling along the Silk Roads, first connected Europe, Africa and Asia.

Researchers at Purdue were first intrigued by the connection when they realized the word for walnut was remarkably similar across a variety of languages.

When researchers began to look at the origins of the word walnut across modern languages, as well as the genetic origins of modern walnut trees, they discovered evolutionary similarities. Just as early traders carried the seeds of new language with them, they also carried walnuts -- likely from only the best trees.

"The factors that contribute to language being dispersed in Asia are the same as the way walnuts were dispersed," Keith Woeste, an adjunct assistant professor of forestry at Purdue, explained in a press release. "It was the unique characteristics of walnut being useful for its wood and nuts that encouraged people to transport it, use it and then plant it as a forest as a long-term investment."

Woeste, who also works as a research geneticist for the U.S. Department of Agriculture's Forest Service, is the lead author of a new paper on the links between language and walnuts -- published this week in the journal PLoS One. His work was assisted by researchers in Italy and England.

The research suggests ancient walnut forests, unlike collections of other ancient trees, are likely no accident, but were some of the first planted orchards.

"It was always assumed that there were wild forests of walnuts, like you'd find wild oak and maple forests here in the U.S.," said Woeste. "But what we had previously considered to be these wild walnut trees out in the middle of Asia were probably planted there."