Universality of language called into question, culture appears to drive underlying grammar of language families

From BBC
Language universality idea tested with biology method
By JASON PALMER
A long-standing idea that human languages share universal features that are dictated by human brain structure has been cast into doubt.

A study reported in Nature has borrowed methods from evolutionary biology to trace the development of grammar in several language families.

The results suggest that features shared across language families evolved independently in each lineage.

The authors say cultural evolution, not the brain, drives language development.

At the heart of both studies is a method based on what are known as phylogenetic studies.

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.

"By looking at variation amongst the descendant plants and knowing how they were related to each other, [Mendel] could work out the mechanisms that must govern that variation," Dr Dunn explained to BBC News.

"He inferred the existence of some kind of information transfer just from knowing family trees and observing variation, and that's exactly the same thing we're doing."

Family trees
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 studies, the team studied the characteristics of word order in four language families: Indo-European, Uto-Aztec, Bantu and Austronesian.

They considered whether what we call prepositions occur before or after a noun ("in the boat" versus "the boat in") and how the word order of subject and object work out in either case ("I put the dog in the boat" versus "I the dog put the canoe in").

The method starts by making use of well-established linguistic data on words and grammar within these language families, and building "family trees" of those languages.

"Once we have those trees we look at distribution of these different word order features over the descendant languages, and build evolutionary models for what's most likely to produce the diversity that we observe in the world," Dr Dunn said.
Pea plants in a greenhouse The methods use inference in a similar way to Mendel's studies of pea plants

The models revealed that while different language structures in the family tree could be seen to evolve along the branches, just how and when they evolved depended on which branch they were on.

"We show that each of these language families evolves according to its own set of rules, not according to a universal set of rules," Dr Dunn explained.

"That is inconsistent with the dominant 'universality theories' of grammar; it suggests rather that language is part of not a specialised module distinct from the rest of cognition, but more part of broad human cognitive skills."

The paper asserts instead that "cultural evolution is the primary factor that determines linguistic structure, with the current state of a linguistic system shaping and constraining future states".

However, co-author and evolutionary biologist Russell Gray of the University of Auckland stressed that the team was not pitting biology against culture in a mutually exclusive way.

"We're not saying that biology is irrelevant - of course it's not," Professor Gray told BBC News.

"But the clumsy argument about an innate structure of the human mind imposing these kind of 'universals' that we've seen in cognitive science for such a long time just isn't tenable."

Steven Pinker, a cognitive scientist at Harvard University, called the work "an important and welcome study".

However, Professor Pinker told BBC News that the finer details of the method need bearing out in order to more fully support their hypothesis that cultural boundaries drive the development of language more than biological limitations do.

"The [authors] suggest that the human mind has a tendency to generalise orderings across phrases of different types, which would not occur if the mind generated every phrase type with a unique and isolated rule.

"The tendency may be partial, and it may be elaborated in different ways in differently language families, but it needs an explanation in terms of the working of the mind of language speakers."

Reference
Dunn M, Greenhill SJ, Levinson SC, Gray RD (2011) Evolved structure of language shows lineage-specific trends in word-order universals. Nature doi:10.1038/nature09923

Abstract
Languages vary widely but not without limit. The central goal of linguistics is to describe the diversity of human languages and explain the constraints on that diversity. Generative linguists following Chomsky have claimed that linguistic diversity must be constrained by innate parameters that are set as a child learns a language1, 2. In contrast, other linguists following Greenberg have claimed that there are statistical tendencies for co-occurrence of traits reflecting universal systems biases3, 4, 5, rather than absolute constraints or parametric variation. Here we use computational phylogenetic methods to address the nature of constraints on linguistic diversity in an evolutionary framework6. First, contrary to the generative account of parameter setting, we show that the evolution of only a few word-order features of languages are strongly correlated. Second, contrary to the Greenbergian generalizations, we show that most observed functional dependencies between traits are lineage-specific rather than universal tendencies. These findings support the view that—at least with respect to word order—cultural evolution is the primary factor that determines linguistic structure, with the current state of a linguistic system shaping and constraining future states.