Oaxaca, Mexico - The small village of San Pedro Sochiapam, deep in the mountainous region of the southern Mexican state of Oaxaca, is home to the Chinantec people. Here steep footpaths end at chicken coops and cornfields grow on mountainsides, while the villagers clear brush with machetes and children enjoy ice-cream cones from a stall near the town hall.
But, in its day to day routines of life, this community is struggling to maintain a unique and important cultural tradition - whistling.
"Chinantec whistled speech is a form of communication where people can really whistle whatever they can say in the spoken language, even though there's more ambiguity in the whistled channel," explains Mark Sicoli, a linguistics professor at the University of Virginia, noting that the presence and absence of glottal stops, tones, and stress patterns make it a particularly productive form of communication.
The sounds carry across canyons better than a shout in sharp, birdlike chirps that allow people to make plans, negotiate, and chat without ever saying a word.
The whistled speech, which can convey past and future tense, comprises seven tones and can be understood at distances of up to one kilometre away.
It can also be transmitted even further, with messages said to wind through the Sierra Madre mountain range to reach a recipient.
Fascinating as it may be, however, the Chinantec community is facing an inescapable reality: Whistled communication, practised since pre-Hispanic times, is slowly falling out of use.
Decline of the whistled language
Marcelino Flores, a local translator, estimates that only a handful of people are still entirely proficient in this musical form of communication. "There is less of a need to whistle today," he says.
He and others say that the decline can be explained by the lack of community conservation efforts aimed at teaching children. Another explanation is the waning interest among young people in farming and agricultural communities where whistled speech is commonly used.
The agricultural sector has suffered a decline in recent decades, especially in coffee production, which is a key sector in the state of Oaxaca.
Until 1990, coffee constituted the third greatest source of foreign exchange in Mexico after oil and cars, with coffee crops in the state of Oaxaca once accounting for more than 30 percent of the state's exports. Climate change, leaf rust, and an international fall in coffee prices have drastically lowered output over the years. As a result, rather than work the land, some Chinantecs have migrated to larger cities in search of better-paid work, and consequently, often lose the art of whistled communication in the process.
"Most children are learning how to whistle but are limited to one or two types," says David Foris, a linguist and author of A Grammar of Sochiapam Chinantec, referring to the various ways whistling sounds can be made, such as with one's tongue or fingers. "It is much less common than it used to be. "
Although cell phone coverage is limited, loudspeakers and walkie-talkies in the town have facilitated long-distance communication, making it less vital for younger generations to whistle as loudly as adults did in the past, Foris says.
"Prior to the introduction of walkie-talkies, the morning air would be filled with whistles across the town as men made their plans for the day," Foris adds, noting that local women understand whistled Chinantec, but usually do not use it.
A worldwide loss of language
The gradual loss of whistled speech, however, is a worldwide concern among other communities that use this form of communication. Whistled speech is now considered a dying art form in localities around the globe, including La Gomera in the Canary Islands, the village of Aas in the French Pyrenees, Kuskuy in the Mediterranean, St Lawrence Island in Alaska, and Papua New Guinea.
In Greece's Antia, for example, only three to four people are fluent whistlers of the local language, according to Whistled Languages: A Worldwide Inquiry on Human Whistled Speech (2015), a book that explores the origins of as well as environmental and geographic factors that have shaped whistled communication.
"When you lose the language, you're not just losing the particular way of communicating and passing things back and forth, but you're also losing the social world that goes along with that," says Paja Faudree, a linguistic anthropologist at Brown University who is studying Mazatec whistled speech in Mexico.
As in other parts of the world, whistled speech in Mexico has deep roots.
This form of communication has been used in other Mesoamerican languages including Mazatec, Zapotec, and Mixtec, and in places such as the central Mexican state of Tlaxcala.
Simeon Carasco, a village elder in San Pedro Sochiapam, expresses his sadness at the loss of this tradition. "From when we were little our grandfathers taught us," he says. "This language is what we do; we have this gift."
In recent years, a language archive that consists of multimedia recordings and transcribed Chinantec whistled conversations has been developed by Professor Sicoli and preserved in archives at The University of Texas at Austin and the Max Planck Institute for Psycholinguistics. Sicoli, along with filmmaker David Yetman, have also made a documentary about the community.
Back in San Pedro Sochiapam, villagers like Marcos Dominguez, remain highly attuned to whistled speech.
While walking toward corn fields, the farmer recalls how one afternoon he heard a whistle and thought someone was trying to get his attention.
"I answered by whistling, 'Here I am,' but I didn't get any response," he says. Then he realised it was just a bird.