Climate shapes how languages evolve

Humidity and temperature are key factors in the ability to form complex tones.
27 January 2015


Languages which rely heavily on tone to convey meaning are more common in warm, humid parts of the world, according to a recent study...

Tone is the variation in pitch which can be used to change the meaning of words or phrases. In English, we use tone to affect the sentence as a whole, such as going up at the end to indicate a question.

However, this isn't the case across the whole world. In as many as half of the world's languages tone is applied to each individual sound, with different tones giving the same word totally different meanings.  These are known as "tonal" languages. For example, in Mandarin the word "ma" can have four meanings: mā (mother), má (hemp), mă (horse) and mà (scold).

A team of researchers from the University of Florida and the Max Planck Intstitute used information on how humidity and temperature affect human vocal chords to predict the regions of the world where tonal languages were most likely to have arisen.

They predicted that warm, humid climes such as Amazonia and South-East Asia would be more favourable to the emergence of tonal languages than the cold or arid conditions such as those found in Northern Europe or the Middle East, which can dry out the vocal chords.

"There is a lot of experimental research suggesting that very dry conditions lead the vocal chords to operate less efficiently," explains Dr. Caleb Everett, one of the team that carried out the research. "In conditions that are really dry, people's vocal chords are not operating as effectively and so it prevents them from making precise tones as easily."

The team mapped in excess of 4,000 languages, both tonal and not, along with average temperatures and humidities across the globe. "What we found was actually exactly what we had predicted," concludes Everett. "The regions of the world that are quite humid are more likely to have tonal languages... Languages with complex tonality do not seem to develop in regions that are very dry or cold."

These findings suggest that it's not just our bodies that have evolved to suit  different habitats, but also our languages, and show how the environment has shaped the evolution of one of the defining characteristics of the human race.


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