Climate May Impact How Human Languages Evolve and Sound

Climate may be to blame for human language. Scientists have long wondered whether climate and geography affect language and now, researchers have untangled the factors that may cause sounds to change.

Many languages of the world use tone or pitch to give meaning to their words. In this latest study, though, researchers found that languages with complex tones-those that use three or more tones for sound contrast-are much more likely to occur in humid regions of the world. Languages with simple tones, in contrast, occur in desiccated regions, such as frigid areas and dry deserts.

"In my estimation, it changes a bit our understanding of how languages evolve," said Caleb Everett, one of the researchers, in a news release. "It does not imply that languages are completely determined by climate, but that climate can, over the long haul, be one of the factors that help shape languages. More broadly, this suggests another non-conscious way in which humans have adapted to their very different and harsh environments. Also, there may be some health benefits to certain sound patterns in certain climates, but more research is needed to establish that in a satisfactory way."

On theory why these differences exist is that inhaling dry air causes laryngeal dehydration and decreases vocal fold elasticity. In other words, it's more difficult to achieve complex tones in arid climates, particularly in very cold ones, when contrasted to warmer and more humid climates. This means that deviations of sounds, including increased jitter and shimmer, are associated with cold and dry climates.

The findings reveal a bit more about human language. More specifically, it shows how our environment can shape the way we speak over time.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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