Language at the Extremes
The rise of molecular technologies yields exciting new routes for studying the biological foundations of human traits. In particular, researchers have begun to identify genes implicated in unusual disruptions of speech and language skills. My talk will show how genetic studies of language at the extremes can provide powerful entry points into critical neural pathways, using FOXP2 as an example. Rare mutations of this gene cause problems with learning to sequence mouth movements during speech, accompanied by wide-ranging deficits in language production and comprehension. FOXP2 encodes a regulatory protein, a hub in a network of other genes, several of which have now been associated with language-related impairments. Versions of FOXP2 are found in similar form in many vertebrates; studies of animals and birds suggest it has conserved roles in the development and plasticity of certain sets of neural circuits. Thus, the contributions of this gene to human traits are likely to involve modifications of evolutionarily ancient functions. The FOXP2 story illustrates the value of an interdisciplinary approach for unravelling the complicated connections between genes, neurons, circuits and human cognitive specializations. An exciting prospect for the future is to target speech and language skills at the other extremes of the distribution, identifying genetic factors that contribute to exceptional abilities.