Blackwell Reference Online

Extract

Parts I to V of the book have dealt with cognitive explanations of reading and reading problems. The two chapters in Part VI move on to consider the biological substrates of reading. Reading depends upon brain mechanisms and the development of these in turn is influenced by genetic mechanisms. Reading in evolutionary terms is a very recent development in the human species, too recent, presumably, for any specific mechanisms to have evolved to allow us to learn to read. In contrast, language is a quintessential human skill that does appear to be a unique evolutionary adaptation of the human species. Pennington and Olson review the massive body of evidence for genetic differences contributing to the development of reading skill, and more specifically genetic influences on the development of dyslexia. It appears that genetic differences among people contribute powerfully to the development of language skills, which in turn are the foundation for learning to read (see chapters in Part II and Part V for elaborations on this point). As Pennington and Olson describe, it is now well established that there is a strong tendency for dyslexia to be inherited, and using molecular genetic methods it has been possible to identify the approximate locations on different chromosomes of a number of risk loci that contribute to the inheritance of dyslexia. It appears that a number of genes contribute ... log in or subscribe to read full text