Numeracy is built in to the brain.

A study appearing in the Proceedings of the US National Academy of Sciences demonstrates that numberacy is built in to the brain, in a similar way that we have the ability to recognise colour. This finding should encourage those afraid of numbers that there is no need to fear them and embracing them will simply release innate abilities. It also supports the notion that practical experience of numbers is a quicker route to numeracy than rote learning.

See the BBC report here.