Lead poisoning isn’t just an industrial-age problem. A new study reveals our ancestors, including Neanderthals, were exposed to lead for millions of years, shaping how their brains evolved and overturning what scientists thought about our toxic history.
Turns out that lead exposure isn’t a purely modern problem caused by industrial pollution. In a new study led by Southern Cross University (SCU), Australia, researchers analyzed teeth belonging to ancient primates and early humans and discovered that lead exposure has been occurring for at least two million years. And it shaped our ancestors’ brains and behavior.
“Our data show that lead exposure wasn’t just a product of the Industrial Revolution – it was part of our evolutionary landscape,” said co-corresponding author, Professor Renaud Joannes-Boyau, PhD, Head of the Geoarchaeology and Archaeometry Research Group (GARG) at SCU. “This means that the brains of our ancestors developed under the influence of a potent toxic metal, which may have shaped their social behavior and cognitive abilities over millennia.”
The team used laser ablation mass spectrometry (LA-MS), a technique that uses direct micro-scale sampling to provide high-precision elemental and isotope analyses of solid materials, to scan Neanderthal molars and other hominid fossils. The Neanderthal samples from Payre, southern France, dated to around 250,000 years ago, contained distinct “bands” of lead inside the teeth, but lead exposure was found in 73% of all the primate and hominid fossils tested, from Africa, Asia, and Europe.
These bands correspond to periods of high lead exposure during tooth formation, indicating that Neanderthals were repeatedly exposed to the metal, likely from natural geological sources such as lead-rich soil, volcanic dust, or, in the case of the Payre sample, water from the limestone environment around the Rhône Valley. Importantly, these patterns weren’t caused by later contamination; they match biological growth layers, proving that the lead was absorbed while the Neanderthals were alive.
Alysson Muotri
The researchers were able to link this ancient exposure to potential neurological effects. In modern humans, lead is a neurotoxin known to impair cognition, learning, and social behavior. We carry the NOVA1 (short for Neuro-Oncological Ventral Antigen 1) gene, which helps control how other genes are used in neurons. In those cells, NOVA1 controls a process called alternative splicing, a kind of molecular “cut-and-paste” that lets one gene produce several different protein versions. By fine-tuning these proteins, NOVA1 helps shape how neurons connect and communicate with each other. Disruption of NOVA1’s activity has been linked to neurological conditions like autism and schizophrenia.
When the researchers introduced lead to human brain organoids – or “mini-brains” – carrying the archaic Neanderthal-like version of NOVA1, which is slightly different to the version that modern humans carry, it disrupted FOXP2, a gene critical for speech and language development. The modern human version of NOVA1 seemed more resistant to lead-related neuronal stress, suggesting that modern humans might have evolved greater resilience to environmental toxins such as lead.
The findings suggest that environmental lead exposure influenced which genetic traits were favored during human evolution, possibly giving modern humans a social or communication advantage over Neanderthals.
“These results suggest that our NOVA1 variant may have offered protection against the harmful neurological effects of lead,” said another of the study’s corresponding authors, Professor Alysson Muotri, from the School of Medicine at UC San Diego. “It’s an extraordinary example of how an environmental pressure, in this case, lead toxicity, could have driven genetic changes that improved survival and our ability to communicate using language, but which now also influence our vulnerability to modern lead exposure.”
“This study shows how our environmental exposures shaped our evolution,” added Professor Manish Arora, from the Department of Environmental Medicine at the Icahn School of Medicine at Mount Sinai, New York, and another corresponding author. “From the perspective of inter-species competition, the observation that toxic exposures can offer an overall survival advantage offers a fresh paradigm for environmental medicine to examine the evolutionary roots of disorders linked to environmental exposures.”
The study was published in the journal Science Advances.
Source: Southern Cross University via Scimex
