The implications for education of an innate numerosity-processing mechanism.

One specific cause of low numeracy is a deficit in a mechanism for representing and processing numerosities that humans inherited and which is putatively shared with many other species. This deficit is evident at each of the four levels of explanation in the 'causal modelling' framework of Morton and Frith (Morton and Frith 1995 In Manual of developmental psychopathology, vol. 1 (eds D Cichetti, D Cohen), pp. 357-390). Very low numeracy can occur in cognitively able individuals with normal access to good education: it is linked to an easily measured deficit in basic numerosity processing; it has a distinctive neural signature; and twin studies suggest specific heritability, though the relevant genes have not yet been identified. Unfortunately, educators and policymakers seem largely unaware of this cause, but appropriate interventions could alleviate the suffering and handicap of those with low numeracy, and would be a major benefit to society.This article is part of a discussion meeting issue 'The origins of numerical abilities'.