Researchers Argue That Human Languages May Adapt Like Biological Organisms

Main Category: Biology / Biochemistry
Article Date: 20 Jan 2010 - 0:00 PDT

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English, for all its confusing spelling and exceptions-if a baker bakes, what does a grocer do?-has a relatively simple grammar. Verbs are easy to conjugate; nouns are mostly pluralized by addings and inanimate objects don't have "genders". In comparison, a language like Hausa has dozens of ways to make nouns plural, and in many languages-Turkish, Aymara, Ladakhi, Ainu-verbs like "know" have to include information about the origin of the speaker's knowledge. This information is often conveyed using complex rules, which languages like English and Mandarin lack.

One prominent hypothesis for why languages differ in these ways is that it is just a matter of random change and historical drift. English and Turkish could be different because of histories that separate them in space and time. Indeed, this has been the reigning assumption in the linguistic sciences.

A recent report, published in the peer-reviewed journal PLoS ONE, offers a new hypothesis, and challenges an explanation based only on drift. Gary Lupyan, of the University of Pennsylvania, and Rick Dale, of the University of Memphis, conducted a large-scale statistical analysis of over 2,000 of the world's languages aimed at testing whether certain social environments are correlated with certain linguistic properties. Their results draw connections between the evolution of human language and biological organisms. Just as very distantly related organisms converge on evolutionary strategies in particular niches, languages may adapt to the social environments in which they are learned and used.

Lupyan and Dale found striking relationships between the demographic properties of a language-such as its population and global spread-and the grammatical complexity of those languages. Languages with the most speakers (and those that have been spread around the world) were found to have far simpler grammars (specifically, morphology) than languages spoken by few people and in circumscribed regions.

For example, languages spoken by more than 100,000 people are almost six times more likely to have simple verb conjugations compared to languages spoken by fewer than 100,000 people. Larger populations tend to have simpler pronoun and number systems, a smaller number of cases and genders, and in general do not employ complex prefixing or suffixing rules in their grammars. A consequence is that languages with long histories of adult learners have become easier to learn over time. Although a number of researchers have predicted such relationships between social and language structure, Lupyan and Dale's study is the first large-scale statistical test of this idea. Statistical controls for geography and Monte Carlo simulations ensured that the reported correlations were not spurious.

How can social environments produce different grammatical patterns? In their paper, Lupyan and Dale propose an explanation that they term the "Linguistic Niche Hypothesis." On their account, languages evolve within particular socio-demographic niches. Although all languages must be learnable by infants, the introduction of adult learners to some languages (e.g., through migration, or colonization) means that aspects of a language difficult for the adults to learn will be less likely to be passed on to subsequent generations of learners. The result is that languages spoken by more people over larger geographic regions have become morphologically simpler over many generations.

A remaining puzzle is why languages with few speakers are so complex in the first place. One possibility explored by Lupyan and Dale is that features such as grammatical gender and complex conjugational systems, while difficult for adult learners to master, may facilitate language learning in children by providing a "network" of redundant information that can cue children in on the meanings of words and how to string them together.

The results and theory proposed by Lupyan and Dale do not aim to explain why a specific language has the grammar it does. Because the findings are statistical in nature, many exceptions to Lupyan and Dale's theory can be identified. Their work, however, provides a comprehensive analysis of how some social factors influence the structure of language and shows that the relationships between language and culture is far from arbitrary.

Funding:

GL was supported by an Integrative Graduate Education and Research Training (IGERT) award to the Institute for Research in Cognitive Science, University of Pennsylvania. RD was supported by National Science Foundation BCS-0720322 and BCS-0826825. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests:

The authors have declared that no competing interests exist

Citation:

"Language Structure Is Partly Determined by Social Structure."
Lupyan G, Dale R (2010)
PLoS ONE 5(1): e8559. doi:10.1371/journal.pone.0008559

Source
PLoS ONE

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