Biocultural evolution and human language diversity

The turn of the century witnessed key developments in biological sciences with profound implications both for biological theory and for the sciences of language. The decoding of the human genome showed that humans share with their closest living relatives, chimpanzees, and bonobos, between 95% and 98% of their genes, depending on the methodology for establishing similarity. This finding threw doubt on the plausibility of the claim that the human language capacity is a consequence of a species-unique, genetically determined neurobiological innovation. Around the same time, it was shown that cultural variation is not unique to the human species; this was initially demonstrated with reference to chimpanzees, but it has since been shown that cultural variation and cultural transmission occurs in a variety of mammalian and avian species. In theoretical biology, the ‘Central Dogma’ of Neo-Darwinism was challenged by the (re-)emergence of ‘Evo-Devo’ and niche construction approaches to evolutionary processes. These developments have led to an increasing acceptance of an Extended Evolutionary Synthesis that goes beyond, and in some crucial respects contradicts, the Neo-Darwinian modern synthesis of the mid-twentieth century. This recasting of evolutionary theory cannot fail to impact the foundations of biolinguistics. Over a roughly contemporaneous period, in the language sciences, the autonomy both of language as a “faculty”, and of grammar from meaning, has been challenged by cognitive linguistics and its more recent companion, cultural linguistics. Together, these developments of recent decades compel the recognition that biology and culture cannot be seen, as they largely were in the last century, as competing ‘causes’ of language and human cognition. A 21st century biolinguistics needs to accommodate the new findings in biology, language sciences (and related disciplines such as archaeology) through the elaboration of a biocultural linguistics that is fundamentally interdisciplinary and is situated in contemporary accounts of both human evolution and linguistic diversity. This chapter will outline the main features of a biocultural science of language and address the complex and dynamical relationship between what all human languages have in common, in what ways they display variation, and how language variation is (and is not) situated in differences between cultures and societies.