New research from the University of Miami is showing that languages with complex tones – like Mandarin – tend to occur more often in humid regions, while languages with simple tones – like Swedish – occur in dry regions.

‘English is a non-tonal language which originates in a relatively dry part of the world. It’s in the top 15 per cent of the ‘driest’ languages. This fits with our hypothesis. It’s perfectly possible that the English language could adopt tones in areas that are now more humid, or as the climate changes,’ says Sean Roberts, who works on global differences in geophonetics. The research changes how language evolution is understood, with data drawn from over half the world’s tongues. ‘Broadly, this suggests another non-conscious way in which humans have adapted to their very different and harsh environments,’ says Caleb Everett, the lead researcher on the project. ‘Also, there may be some health benefits to certain sound patterns in certain climates, but more research is needed.’ Inhaling dry air may cause a speaker’s voice box to dehydrate, decreasing voice range.

‘There’s a hypothesis several anthropologists have put forward that languages in warmer climates such as Kenya tend to have higher rates of mouth opening,’ says Everett.

‘Languages do gain and lose tone, and can do so quite quickly. Ancient dialects of Chinese had no tone, and Korean is currently undergoing ‘tonogenesis’ (gaining tones),’ adds Roberts. At present, it’s very difficult to say whether very early languages had tone or not.

‘One of the things we’ll be researching next is whether languages gain or lose tone when entering or leaving dry climates,’ says Roberts. ‘This will involve reconstructing linguistic history using statistical methods. Effectively, this will also involve modelling climate change.’

This story was published in the March 2015 edition of Geographical Magazine