A groundbreaking study from Southern Cross University in Australia has revealed that ancient lead exposure has significantly influenced the evolution of both Neanderthals and modern humans. This research indicates that lead poisoning is not merely a consequence of industrial activities but has been part of human history for at least two million years.
Researchers analyzed teeth from ancient primates and early human ancestors, discovering patterns of lead exposure that date back to a time when Neanderthals roamed the Earth. Co-corresponding author, Professor Renaud Joannes-Boyau, PhD, who leads the Geoarchaeology and Archaeometry Research Group at SCU, emphasized that the findings challenge previous beliefs regarding the timeline of lead exposure. “Our data show that lead exposure wasn’t just a product of the Industrial Revolution – it was part of our evolutionary landscape,” he stated.
The study utilized advanced laser ablation mass spectrometry (LA-MS) to conduct precise elemental analyses of Neanderthal molars and other hominid fossils. Notably, samples from Neanderthals in Payre, France, dating back approximately 250,000 years, exhibited distinct bands of lead within their teeth. In total, lead exposure was detected in 73% of the primate and hominid fossils examined from regions across Africa, Asia, and Europe.
The presence of these lead bands corresponds to periods of high exposure during the formation of teeth, indicating that Neanderthals encountered lead from natural geological sources. These sources included lead-rich soil, volcanic dust, and mineral-rich water found in the limestone environment surrounding the Rhône Valley. Importantly, the lead patterns observed were not due to later contamination but matched biological growth layers, confirming that absorption occurred while the Neanderthals were alive.
The implications of this ancient lead exposure extend to potential neurological effects. In contemporary humans, lead is recognized as a neurotoxin that can impair cognitive abilities and social behavior. The study highlights the NOVA1 gene, which plays a crucial role in neuronal function by regulating how genes are utilized in neurons. Disruptions to NOVA1 have been associated with neurological conditions such as autism and schizophrenia.
When researchers introduced lead to human brain organoids—miniature models of the human brain—carrying the archaic Neanderthal-like version of NOVA1, they observed disruptions in the FOXP2 gene, essential for speech and language development. In contrast, the modern human version of NOVA1 appeared more resilient to lead-induced neuronal stress, suggesting that modern humans may have evolved enhanced resistance to environmental toxins like lead.
The findings propose that ancient lead exposure may have influenced which genetic traits were advantageous during human evolution, potentially granting modern humans a communicative edge over Neanderthals. “These results suggest that our NOVA1 variant may have offered protection against the harmful neurological effects of lead,” noted Professor Alysson Muotri from the School of Medicine at the University of California, San Diego.
Professor Manish Arora from the Department of Environmental Medicine at the Icahn School of Medicine at Mount Sinai in New York added, “This study shows how our environmental exposures shaped our evolution.” He highlighted that understanding the impact of toxic exposures on survival could offer new insights into environmental medicine and its link to disorders related to environmental factors.
The research was published in the journal Science Advances, marking a significant contribution to our understanding of the interplay between environmental factors and human evolution. This study not only sheds light on the ancient past but also raises awareness about the ongoing impacts of lead exposure in modern populations.
