Growth Models of Developmental Language Disorders

The prior quote is from a recent issue of Science with a special section on the topic of developmental timing. The temporal events that guide development are key parts of the puzzle of contemporary molecular genetics. Genes are known to turn on at certain times in development; microRNAs show temporaland tissuespecific patterns of gene expression (cf. Carrington & Ambros, 2003); and genes activate to trigger downstream developmental events removed in time from the triggering event (cf. Gehring & Ikeo, 1999; Marcus & Fisher, 2003). Timing mechanisms are fundamental to the way that inherited elements direct an individual’s growth, whether at the cellular or organism level. The fact that language acquisition is a developmental phenomenon that emerges in the early childhood period is a commonplace observation that is known to parents and scholars alike. The literature is full of debates about the extent to which growth in language early on is attributable to inborn, language-specialized mechanisms; inborn, generalized learning mechanisms that are heavily influenced by environmental input; or fundamental learning 10