Do Genetic Differences Affect Language Evolution?

Language is a hallmark of modern humans: only humans have language. Yet, while no human society lacks a language, individual languages exhibit wide variety.  In this, language differs greatly from bipedalism, the other hallmark of humans. We explore the question of whether there is a relation between the variety among languages and genetic variation, concentrating on the emergence of sign languages in societies with a high incidence of deafness due to genetic traits.  We show that the emergence of sign languages in such societies is also tied to a number of preexisting cultural factors.  This type of interaction, where genetics and culture, both separately and together, provide the foundation for a particular type of language, has not previously received attention.