As anyone who has ever been to a hog-calling contest or a middle school cafeteria can attest, humans are capable of producing all sorts of sounds. But most languages take advantage of only a small portion of these. English, for instance, has just 42 or so distinct sounds, a fraction of our species' vocal capabilities.
So why do some languages pick up some sounds and eschew others? Most linguists have assumed that it's more or less random, but a new study suggests that geography might play a role.
One particular type of sound called the ejective consonant, a sort of puh, kuh, or tuh noise produced by creating a pocket of air in the throat and compressing it. We don't have ejective consonants in English, but about one in five languages have them, mostly in eastern and southern African languages, and in indigenous languages in the western parts of North and South America. Ejective consonants can also be found in the Caucasus.
University of Miami anthropologist Caleb Everett noticed that languages of people living at high elevations tend to have ejective consonants and that those in low-lying areas tend to lack them. He went through the World Atlas of Linguistic Structures Online, a huge database of languages and their phonological, lexical, and grammatical properties, and compared them with the geographic coordinates and elevations of the languages' locations.
Of the 567 languages that he analyzed – about 8 percent of the 6,909 or so human languages – Dr. Everett found that about 87 percent of languages with ejective consonants have their origins within about 300 miles of high elevation points, defined as regions about a mile above sea level or higher.
Why is this so? Everett suspects the rarefied air found at high altitudes makes it easier to hold air pockets in the throat. "Since atmospheric pressure is reduced at higher elevation," he writes in the current issue of the journal PLOS ONE, "we speculated that this compression would be more easily achieved in locations of relatively high elevation."
In his study, Everett also offered a second possible explanation. It could be the case, he writes, that ejective consonants tend to mitigate the loss of water vapor. As chatty mountaineers tend to quickly discover, talking too much at altitude can lead to dehydration. Ejective consonants tend to expel less vapor than those originating in the lungs, so it could be that our languages are shaped by our bodies' water conservation strategies. Or it could be a combination of both explanations.
Everett's is not the first study to link human sounds to geography. A paper in 2004 noted a correlation between sonority – that is, those with more frequent vowel sounds and a greater amplitude – and proximity to the equator. Linguists suggest that cultures in warmer places rely on speaking across greater distances.