Quantifying Quantitative Literacy: Age Heaping and the History of Human Capital

Age data frequently display excess frequencies at attractive numbers, such as multiples of five. We use this "age heaping" to measure cognitive ability in quantitative reasoning, or "numeracy". We construct a database of age heaping estimates with exceptional geographic and temporal coverage, and demonstrate a robust correlation of literacy and numeracy, where both can be observed. Extending the temporal and geographic range of our knowledge of human capital, we show that Western Europe had already diverged from the East and reached high numeracy levels by 1600, long before the rise of mass schooling or the onset of industrialization.