Ancient Polluters

Humans have polluted the environment for thousands of years: Now, a new study shows that contamination involving lead is even older than initially thought.

Researchers analyzed how and when early human activities impacted ecosystems by studying 14 sediment cores collected from the Aegean Sea floor and the surrounding coastline between 2001 and 2021.

The analysis of one core from a peat bog provided the earliest evidence of environmental lead pollution – researchers dated it to 5,200 years ago, about 1,200 years earlier than they thought, based on the evidence they collected.

Because lead was released during the production of silver, finding traces of this metal in the environment not only provides insights into how human activities affected ecosystems but is also an indicator of socioeconomic change.

Besides lead, the sample analyzed contained pollen, which allowed for reconstructing vegetation development in the area and understanding how ancient civilizations used land.

According to the researchers, the data on lead contamination and vegetation development show when societies transitioned from agricultural to monetary and how this change impacted the environment.

The composition of the pollen spectra shows that about 2,150 years ago, there was a rise in lead concentrations accompanied by intense deforestation and increasing agricultural use.

Lead contamination in sediment from the sea floor emerged around that same time and is considered the earliest worldwide record of human-caused lead pollution in the ocean, said the researchers.

“The changes coincide with the conquest of Hellenistic Greece by the Romans, who subsequently claimed for themselves the region’s wealth of resources,” said Heidelberg archeologist Joseph Maran in a statement.

The Romans significantly increased the mining of gold, silver, and other metals, with ore extraction and smelting also requiring wood, researchers added.