A new study published in Science Advances suggests that humans and their ancestors were exposed to lead nearly two million years ago — and that this toxic element may have shaped the evolution of our brains and language.

Reconstruction of a Neanderthal hunter at the Neanderthal Museum. Credit: Neanderthal-Museum, Mettmann/CC BY-SA 4.0

An international team led by researchers from the University of California San Diego and Southern Cross University analyzed 51 fossilized teeth from Homo sapiens, Neanderthals, and extinct apes such as Gigantopithecus blacki. The fossils, which date to between 100,000 and 1.8 million years ago, were found in Africa, Asia, and Europe. Scientists detected lead in 73 percent of the samples using high-precision laser-ablation geochemistry, which shows that ancient hominins were chronically exposed to the metal.

In contrast to industrial or gasoline-emitted pollution in the modern age, prehistoric lead had a natural origin — from soil, volcanic dust, and water flowing through mineral-rich caves. The evidence overturns the belief that lead exposure is a modern phenomenon.

Lead is highly toxic, particularly to developing brains. Even small doses of exposure can impair cognition and communication — two abilities necessary for survival and cooperation. The researchers wondered why early Homo sapiens were able to thrive in such conditions, whereas Neanderthals and other relatives disappeared.

A reconstruction of a Homo sapiens (left) and a Neanderthal (right). Credit: Paul Hudson, Flickr / Wolfgang Sauber, CC BY-SA 4.0. Edit and composite by Archaeology News Online Magazine.

The answer could lie in one gene, called NOVA1, that regulates the development of the brain and neural communication. Modern humans share a slightly different version of NOVA1 than Neanderthals — a difference of just one base pair in DNA. To experiment with its effect, the researchers grew tiny brain “organoids” in a laboratory using both modern and ancient versions of the gene, and then exposed them to lead.

The results were astounding. Organoids with the modern human NOVA1 were more resistant to lead’s effects, maintaining healthy brain cell growth. The ancient variant, however, experienced disruptions in the FOXP2 gene, which is essential for speech and language development. This suggests that the human-specific mutation of NOVA1 may have protected our ancestors’ brains, allowing language and complex communication to flourish.

The researchers speculate that this genetic advantage gave Homo sapiens a key edge over Neanderthals and other hominins. Enhanced communication likely improved social cohesion, cooperation, and cultural transmission — all of which helped modern humans survive environmental stress and spread across the globe.

However, scientists caution that more research is needed. Even though the study indicates a fascinating link between environment, genetics, and evolution, it remains a hypothesis supported by experimental and chemical evidence, and not by actual DNA from fossils.

In spite of this, the study presents an unexpected revelation: a ᴅᴇᴀᴅly metal that once threatened our ancestors may actually have pushed evolution to favor a more communicative, adaptive species.

More information: University of California San DiegoPublication: Joannes-Boyau, R., de Souza, J. S., Arora, M., Austin, C., Westaway, K., Moffat, I., … Muotri, A. R. (2025). Impact of intermittent lead exposure on hominid brain evolution. Science Advances, 11(42), eadr1524. doi:10.1126/sciadv.adr1524