Ancient Romans' IQ was reduced by the
lead in the air they breathed, a new study says.
The thirst for silver needed to mint sesterces had deleterious
consequences for the health of the citizens of the Roman Empire,
according to new research published in the Proceedings of the
National Academy of Sciences.
The descendants of Romulus and Remus breathed in considerable
quantities of lead linked to the mining of the precious metal
and this caused a drop of 2.5 to 3.5 points in their IQ, said
study by the Desert Research Institute in Nevada.
Th research reconstructed the link between the Romans' passion
for silver and lead pollution in Europe over a millennium,
between 500 BC and 600 AD.
Based on core samples from Arctic ice, the research has not,
however, resolved the age-old dilemma of whether lead poisoning
played a role in the fall of the empire.
"I think it was one of the factors, but not the only one, that
contributed to the decline," Bruce Lanphear, a specialist at
Simon Fraser University in Canada who was not involved in the
new research, told NBC.
While Joseph McConnell, an environmental scientist and the
study's lead author, said the team had still discovered the
"first example of industrial pollution in the history of the
world."
Lead is a byproduct of silver mining: "To produce 100 grams of
silver, you've produced a ton of lead," McConnell told the New
York Times.
The researchers found traces of lead in ice sheets collected in
Russia and Greenland dating back to the empire.
Lead was released into the atmosphere by mining, transported by
air currents and finally deposited in the Arctic as snow.
The lead levels measured by McConnell and his collaborators are
extremely low, about one molecule of lead per trillion molecules
of water.
Yet the ice samples were collected thousands of miles from the
epicenter of the empire, and lead concentrations would have
dispersed significantly over the long journey.
To estimate how much lead Roman mining originally emitted, the
researchers worked backwards.
Using computer models of Earth's atmosphere and making
assumptions about the locations of mining sites, the team varied
the amount of lead emitted to match the concentrations measured
in the ice.
In one case, they assumed that all silver production occurred at
the major Rio Tinto mining site in southwest Spain.
In another case, they assumed that silver mining was evenly
distributed among dozens of sites.
The team calculated that Roman mining emitted 3,300 to 4,600
tons of lead into the atmosphere.
The researchers then estimated how all that lead would have been
dispersed throughout the empire to arrive at a calculation,
using the parallel with contemporary data, of how much of that
lead would have entered the blood of the citizens of the empire,
particularly children, resulting in a decline in intellectual
capacity.
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