"A 2 to 3 points lower IQ doesn't sound like much, but when you apply that to the entire European population, it's quite a lot."

DRI scientists analyzed Arctic ice core records to reconstruct historical atmospheric lead pollution from Ancient Rome, uncovering a link between lead exposure and cognitive decline. Lead exposure is a significant public health concern,

Using modern evidence of lead pollution and its health effects, the international team calculates that lead exposure in the Roman golden age could have caused a population-wide drop in IQ of about 2.5 to 3 points per person. And that goes for most of the Roman Empire, including its provinces of Gaul, northwestern Africa, Iberia, and Britannia.