Most of the news about minority languages is that they’re endangered or dying off, and the only new languages we hear about are those created for Hollywood sci-fi blockbusters. But sometimes, linguists find a previously unrecorded language — and when they do, it’s a sign language. The reasons for this discovery aren’t mysterious. “Because of the sporadic incidence of deafness, the generation-to-generation transmission of language is disrupted,” says Richard Meier, a linguist and sign language expert at the University of Texas at Austin. “Deafness may appear in communities that had not previously had it. Because of their hearing loss, the deaf are likely unable to acquire the local spoken language. But the community may lack an established sign language.” The result? People create languages.

Researchers Lynn Hou, Kate Mesh and Hilaria Cruz On her first fieldwork trip in 2010, linguist Lynn Hou, who is deaf, and her colleague at the University of Texas at Austin, Hilaria Cruz, from the southern Mexican state of Oaxaca, visited the villages of San Juan Quiahije and Cieneguilla. Cruz had grown up signing to deaf family members. On their trip, Hou met some deaf adults and learned the signs they use. She suspected that they weren’t using Mexican Sign Language. Several years later, Hou returned to Oaxaca with a collaborator, linguist Kate Mesh. There they confirmed that people were using a unique sign language that had been invented locally. In the spring of 2014, Hou received grants from the National Science Foundation and the National Institutes of Health to study Chatino Sign Language. (Chatino is the Spanish name for the indigenous people of the area as well as the name of their spoken language.)

Hou’s discovery is one of about a dozen sign languages identified for the first time by linguists in the last decade, and more are popping up. Most recently a group of American and Israeli linguists have been studying two new sign languages in Israel, one of which arose only four generations ago in a Bedouin village with an unusually large deaf population. Such “village sign languages,” as they’re called, appear all over the world. There is Ban Khor, a sign language used by about a thousand people in a village in Thailand; Adamorobe, a language in Ghana that shares a number of traits with other West African sign languages, like loose hand shapes and sweeping gestures; and Kata Kolok (literally “deaf language”), which developed in Bengkala, Indonesia, where villagers share a belief in Bhatara Kolok, a deaf god. Linguists are also investigating new sign languages in the Yucatan Peninsula of Mexico as well as Turkey. These sign languages help scientists understand how humans create a new language. Because they are so new, they don’t have the same complex structure that older, more established spoken and signed languages have. Nevertheless, they are fully functional languages, used by hearing and deaf people to share information, tell jokes and stories, make speeches and share emotional intimacies. “It is natural to assume that there can be little direct evidence that casts light on the evolution of language, because its origins are lost in the prehistory of our species,” says Simon Kirby, who studies the evolution of language at the University of Edinburgh. “But recently there has been a growing realization that not only biological but also cultural evolution has an important role to play in understanding language origins.”

Scientists look at language as a complex adaptive system influenced by numerous factors — the limits of the human brain, the size of the groups, the number of deaf people in each family, and even social interactions based on gender.

These new sign languages are also challenging some long-held assumptions about what is universal in human languages. One characteristic of most languages is that speakers are able to build very complex structures, such as sentences, out of a simple set of more basic units, like words. In spoken languages, the basic units are sounds; in sign languages, they are shapes of the hand. But some of the village sign languages don’t have this property, which has long baffled linguists. One proposal is that the signs haven’t become fully conventional yet because they often “look like” objects or actions, a quality that young sign languages exploit early in their lives. But linguists don't yet know when this structure emerges or how. It was also assumed that all sign languages use the space around a signer’s body to change what verbs mean (such as when an action occurred, or whether it is ongoing), but some of the sign languages that have been found in villages don’t do this. Researchers are looking at what it means if they're the only sign languages without it. Is it a function of their young age? Or is there some other reason? Linguists of the past, inspired by the work of Noam Chomsky, would have tried to figure out some innate, uniquely human order in these sign languages. Nowadays, contemporary scientists like Simon Kirby look at language as a complex adaptive system that is influenced by numerous factors — not only the limits of the human brain but the size of the groups, the number of deaf people in each family, and even social interactions based on gender. “I hope this research will reveal more precisely how initially improvised communication becomes conventional and then systematic through a process of cultural evolution,” Kirby says. To study this, researchers are comparing descriptions of the language environment with computer models and laboratory experiments. For instance, Tessa Verhoef, a computer scientist at the University of California-San Diego’s Center for Research in Language, is studying how people simplify a sequence of slide whistle sounds when they teach it to others. She is also running experiments in which people learn and teach sequences of gestures. “We are creating chains of transmission which would simulate the way that languages are passed from generation to generation,” Verhoef says. These simulations can be compared to findings from the field made by people like Hou and Mesh.

Watching this process unfold in real time reveals how simple symbols may have evolved into something more complex around 150,000 years ago.