GENETIC BASIS OF LANGUAGES

GENETIC BASIS OF LANGUAGE

Introduction
The Genetic Architecture of Language

This article surveys what is currently known about the complex interplay between genetics and the language sciences. It focuses not only on the genetic architecture of language and speech, but also on their interactions on the cultural and evolutionary timescales. Given the complexity of these issues and their current state of flux and high dynamism, this article surveys the main findings and topics of interest while also briefly introducing the main relevant methods, thus allowing the interested reader to fully appreciate and understand them in their proper context. Of course, not all the relevant publications and resources are mentioned, but this article aims to select the most relevant, promising, or accessible for nonspecialists. The main author of this article, Dan Dediu, was funded by the NWO (Netherlands Organisation for Scientific Research) Vidi Grant no. 276-70-022. The authors also want to thank the members of the Language and Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands, for helpful suggestions.

                                             

                   

 Studies of genetic disorders also reveal that one cognitive domain can develop normally along with anormal developmemt un other domains, and they also underscore the strong biological basis of language .children with Turner syndrome 

 view that genetics must contribute to our species’ linguistic abilities has existed for many years, as illustrated by  Chomsky and Lennerberg with pinker and bloom  o an influential evolutionary point of view. However, the discovery of concrete genetic influences on language had to await the development of modern DNA technologies. As has been the case for many aspects of human biology, the first insights into the genetic basis of language have come from the study of disorders, discussed in detail in the sections Rare speech and languages Disorders  and common Disorders of speech and language. The classification of disorders as rare or common very likely reflects the underlying architecture—rare diseases tend to be caused by single mutations of large effect within one particular gene, while common ones have more heterogeneous genetic architectures involving common variants with small effect, as well as rare variants in a number of different genes. While rare disorders can clearly be classified as abnormal, the genetic architecture of common disorders puts them on a spectrum with normal variation. Discussions of the genetic architectures of complex traits and common neurodevelopmental disorders, a useful context in which to understand language and speech, are provided in Betancur 2011 and Durand AND Rappold 2013.

Daniel Geschwind reaches up to his office bookshelf, takes down a three-dimensional puzzle of the human brain, and begins trying to snap the plastic pieces together. A neurogeneticist at the University of California, Los Angeles, Geschwind hopes the puzzle will help him describe the parts of the brain that control speech and language. But for the life of him, he can’t figure out how the left and right hemispheres attach. “I’m really bad spatially, so don’t make fun of me,” he pleads. “It’s like I’m having a little stroke or something. I’ll get it together, and then I’ll figure it out.