Extensive silver mining may have exposed ancient Romans to high levels of lead pollution in the air, probably leading to a general drop in their IQ and their resistance to disease.

Analyses of Arctic ice layers point to concentrations of atmospheric lead at the Roman Empire’s height that were about threefold what they are today in the US. The effect on the intelligence of ancient people across Europe – especially in major coin-making regions in Iberia – would have been significant and might have even made…