Word acquisition reflects lateralization of hand skill

Right hand preference distinguishes Homo sapiens from our closest primate relative, the chimpanzee. Are differences in degrees of handedness associated with differences in the rate of language development? To answer this question, verbal performance is examined in relation to hand skill in a UK national birth cohort dataset. Using 3-D data plots, we show that increasing dominant-hand skill is associated with increasing verbal ability, and stronger lateralization is associated with earlier acquisition of words. Thus, right-handed bias is relevant to the lateralization of language; variation along this dimension may represent species-specific genetic or 'epigenetic' diversity.