Tonal languages require humidity

January 22, 2015
Languages in humid regions of the Earth (light circle) are more often tonal languages (red) than in dry regions. Credit: MPI f. Psycholinguistics/ Roberts

The weather impacts not only upon our mood but also our voice. An international research team including scientists from the Max Planck Institutes for Psycholinguistics, Evolutionary Anthropology and Mathematics in the Sciences has analysed the influence of humidity on the evolution of languages. Their study has revealed that languages with a wide range of tone pitches are more prevalent in regions with high humidity levels. In contrast, languages with simpler tone pitches are mainly found in drier regions. This is explained by the fact that the vocal folds require a humid environment to produce the right tone.

The tone pitch is a key element of communication in all languages, but more so in some than others. German or English, for example, still remain comprehensible even if all words are intonated evenly by a robot. In Mandarin Chinese, however, the pitch tone can completely change the meaning of a word. "Ma" with a level pitch means "mother," while "ma" with a falling then rising pitch would mean "horse". "Only those who hit the tone pitch correctly can express themselves in tonal languages," explains Seán G. Roberts, a scientist at the Max Planck Institute for Psycholinguistics in Nijmegen.

However, the climate can become a problem for the speakers of tonal languages, as the in the larynx – commonly known as the voice box – suffer as a result. Even a temporary increase in humidity impacts upon the vocal folds: The humidity keeps the mucous membranes moist and makes them more elastic. It also changes the ion balance within the of the vocal folds. With good humidity, the vocal folds can oscillate sufficiently and produce the right tone.

This map shows the distribution of languages with complex tone (red dots) and without complex tone (blue dots) in the Phonotactics Database of the Australian National University. Darker shading on map correspondsto lower mean specific humidity. Credit: Caleb Everett / University of Miami

The scientists therefore suspect that tonal languages are less common in dry regions as the wide range of tonal pitches is difficult to produce under these conditions and are more likely to result in misunderstanding. "Modern databases enable us to analyse the properties of thousands of languages. But this also brings problems because languages can also inherit their complex pitches from another language," says Damián E. Blasi, who conducts research at the Max Planck Institutes for Mathematics in the Sciences and for Evolutionary Anthropology in Leipzig. In their study, the scientists have now shown that these effects can be disentangled from the effects of climate.

The video will load shortly
A phrase in Cantonese, an example of a tonal language. University of Miami linguist Caleb Everett has published research showing that climate affects whether a language develops to be tonal or non-tonal. Credit: University of Miami Communications

The video will load shortly
A phrase in English, an example of a non-tonal language. University of Miami linguist Caleb Everett has published research showing that climate affects whether a language develops to be tonal or non-tonal. Credit: University of Miami Communications
The researchers investigated the correlation between humidity and the significance of tone pitch in over 3,750 languages from different linguistic families. This indicates that tonal languages are significantly rarer in dry regions. In relatively dry Central Europe, no tonal languages have developed like those found in the Tropics, Subtropical Asia and Central Africa.

Climate apparently shapes the role of pitch tone in a language and therefore how information is exchanged. Even small effects may be amplified over the generations to produce a global pattern. The climate thus determines the development of languages. "If the UK had been a humid jungle, English may also have developed into a tonal language," explains Roberts.

Explore further: Perfect pitch: Knowing the note may be in your genes

More information: "Climate, vocal folds, and tonal languages: Connecting the physiological and geographic dots." PNAS, 19 January 2015. DOI: 10.1073/pnas.1417413112

Related Stories

Perfect pitch: Knowing the note may be in your genes

October 23, 2012

People with perfect pitch seem to possess their own inner pitch pipe, allowing them to sing a specific note without first hearing a reference tone. This skill has long been associated with early and extensive musical training, ...

"Kernel" lexicon of languages remains stable in the long run

October 7, 2014

The frequency with which we use different words changes all the time, new words are invented or fall out of use. Yet little is known about the dynamics of lexical change across languages. Researchers of Kazan Federal University ...

Perfect Pitch: Language Wins Out Over Genetics

May 19, 2009

Mozart, Tchaikovsky, Sinatra and Hendrix -- these and many other of the world's most famous musicians have had "perfect" or "absolute" pitch. The ability, defined as recognizing the pitch of a musical note without having ...

While old Indigenous languages disappear, new ones evolve

October 29, 2014

By now we know that traditional Indigenous languages are losing speakers rapidly and tragically. Of the 250 languages once spoken in Australia, only 40 remain and just 18 of these are still learnt by children. But if children ...

Recommended for you

Amber specimen offers rare glimpse of feathered dinosaur tail

December 8, 2016

Researchers have discovered a dinosaur tail complete with its feathers trapped in a piece of amber. The finding reported in Current Biology on December 8 helps to fill in details of the dinosaurs' feather structure and evolution, ...

Scheduling leisure activities makes them less fun: study

December 8, 2016

Nothing ruins a potentially fun event like putting it on your calendar. In a series of studies, researchers found that scheduling a leisure activity like seeing a movie or taking a coffee break led people to anticipate less ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Nik_2213
1 / 5 (2) Jan 22, 2015
"If the UK had been a humid jungle..."
{Cough}

We're a 'Western Maritime' clime, which brings lots and lots of rain. In fact, our Summers may be enduringly sodden, and our Winters miserably dank.

Pretty hypothesis, but needs a 'reality check'.
alfie_null
1 / 5 (1) Jan 23, 2015
It could be argued that English, anymore, is a polyglot. A mongrel that can claim no home.

I wonder if a similar correlation could be found regarding the use of voice in music?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.