Studies: How Climate Influenced Human Speech Development

How Climate Influenced Human Language and Speech Development

Variations in human speech exist across regions and continents. Linguists and researchers have long debated whether geography has affected this phenomenon. Nonetheless, a group of researchers uncovered a striking pattern: variations in human speech correlate with variations in climate or prevailing geographic temperature.

Research: The Impact of Climate on the Development of Human Speech

Researchers from the University of Miami, the Max Planck Institute for Evolutionary Anthropology, and the Max Planck Institute for Psycholinguistics examined more than 3700 languages across different regions of the globe.

Caleb Everett, Damián E. Blasi, and Seán G. Roberts intended to draw a connection between climate and human speech development. Their specific goal was to determine an association between the environment and consistency in vocal sounds across different languages in different geographic areas.

Results showed that out of the examined languages, 629 have complex tones and interestingly, these languages are spoken in tropical regions including Africa and Southeast Asia, as well as in humid regions of North America, Amazonia, and New Guinea.

Hence, the study implies that languages with complex tones or those that use three or more tones for sound contrast, are more likely to have developed and occurred in humid regions as opposed to languages with simple tones that are commonly found in desiccated regions, whether frigid areas or deserts.

“In my estimation, it changes a bit our understanding of how languages evolve,” said Everett, lead researcher and professor in the Department of Anthropology at the University of Miami. “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.”

Everett added: “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.”

Drawing from extensive experimental data cited in the research, the researchers explained that inhaling dry air commonly found in dry or cold areas causes laryngeal dehydration and decreases vocal fold elasticity. The resulting sounds produced by the vocal cords are jittery and shimmery. Over the long run, the environmental or to be specific, the climatic condition caused the adoption of easy-to-produce sounds or simple vocal tone and pitch.

A follow-up study also laid down four points to support the earlier study. First, human behavior is generally adaptive and there is no evidence that this does not extend to linguistic structure. The second is that animal communication systems are known to be adaptive within species across various phyla and taxa.

The third point asserts that research in laryngology shows that ambient conditions can impact the performance of the human vocal cords, which suggests a clear and testable hypothesis about the global distribution of language types. Finally, according to the fourth point, the idea that the sound systems of human languages are adapted to their environment has been supported by the previous study and it is time to more seriously consider the possibility that linguistic sound systems are adapted to their physical ecology.

Summary and Takeaway: Climate as a Factor in Human Language Evolution

There is some evidence that the physical environment, including climate, can influence the development and evolution of human language. For example, research has suggested that certain aspects of language structure, such as vowel systems and consonant inventory size, may be influenced by the physical environment in which a language is spoken.

One example of this is the fact that languages spoken in hot and humid environments tend to have a larger number of vowel sounds, which may be related to the fact that these sounds are produced with less tension in the vocal tract, making them easier to produce in such environments. In contrast, languages spoken in colder environments with dry air may have a smaller number of vowel sounds, as the production of these sounds requires more tension in the vocal tract, which may be more difficult to sustain in such environments.

It is important to note that the influence of the physical environment on language is just one of many factors that can shape the structure and evolution of language. Other factors, such as cultural and social influences, also play a significant role in shaping language.


  • Everett, C., Blasi, D. E., and Roberts, S. G. 2016. “Language Evolution and Climate: The Case of Desiccation and Tone.” Journal of Language and Evolution. 1(1): 3-46. DOI: 1093/jole/lzv004
  • Everett, C., Blasi, D. E., and Roberts, S. G. 2015. “Climate, Vocal Folds, and Tonal Languages: Connecting the Physiological and Geographical Dots.” PNAS. 112(5): 1322-1327. DOI: 1073/pnas.1417413112