In my dissertation, I focus on the documentation and comparison of indigenous sign languages in Yucatán, Mexico. I conducted fieldwork in four Yucatec Maya communities with a high incidence of deafness. Because deaf people born into these villages have never had access to an established sign language, they have developed their own local sign languages to communicate with each other and their hearing relatives. Yucatec Maya Sign Languages (YMSLs) are young languages that have emerged over the past decades.

The sign languages in the four communities are historically unrelated, but their shared cultural background and the influence of co-speech gestures used by hearing speakers of Yucatec Maya lead to striking similarities in their lexicon and grammar. At the same time, YMSLs display a high degree of variation related to sociolinguistic factors, such as family membership, age, education or language acquisition from deaf adults. In my dissertation, I argue that we can use the phenomenon of variation in young, micro-community sign languages as a window to find out how linguistic conventions are established and which sociolinguistic variables are relevant for shaping sign language structures.

My dissertation consists of four sub-studies. In Study I, I employ the framework of translanguaging to examine the semiotic resources used by deaf and hearing Yucatec Maya to interact with each other and with people from other communities. I demonstrate that the repertoire of Yucatec Maya conventional gestures, positive attitudes towards deafness and sign language, as well as shared cultural knowledge, facilitate communication between deaf and hearing people and lead to overlap between sign languages without any historical affiliation. This study constitutes the first application of the translanguaging theory to studies of sign language emergence. Study II investigates cardinal numbers in YMSLs from three villages. I found that some features of Yucatec Maya counting gestures are preserved but that distinct number paradigms evolved in the three YMSL communities. YMSL numerals exhibit variation as a result of linguistic and sociolinguistic factors. Study III explores how YMSL signers convey a linguistic distinction between objects and actions and discusses if these strategies more generally distinguish nouns from verbs. Two possible strategies of the noun-verb distinction were examined; both have an equivalent in hearing people’s gestures but have been integrated into YMSLs in different ways. In Study IV, I focus on a conventional gesture used by hearing Yucatec Maya to specify the height of upright – usually human – referents and analyse how it has been incorporated into YMSLs from four villages. Comparing the form, meaning and distribution of height-specifiers in Yucatec Maya gestures and YMSLs, I demonstrate paths of lexicalisation and grammaticalisation from gesture to sign.

Apart from providing documentation of underdescribed, endangered languages, my dissertation makes several theoretical contributions. I demonstrate that language age is not the only variable relevant to the emergence of complex linguistic structures, but that other sociolinguistic factors, such as the distribution of deafness across families, networks of interaction and attitudes toward deafness play a role. Moreover, I present evidence that gestures can enter lexicon and grammar of a sign language simultaneously, challenging previous accounts of lexicalisation and grammaticalisation.