Ancient Lead Exposure Influenced Evolution of Neanderthal Brains

A groundbreaking study reveals that lead exposure has significantly influenced the evolution of the brains of Neanderthals and early humans, dating back at least two million years. Researchers from Southern Cross University (SCU) in Australia analyzed ancient teeth and discovered that lead poisoning was a persistent issue long before the industrial age. This research challenges previous assumptions about the timeline of environmental toxins impacting human evolution.

The study, led by Professor Renaud Joannes-Boyau, Head of the Geoarchaeology and Archaeometry Research Group at SCU, highlights that exposure to lead was not solely an effect of industrial activities. “Our data show that lead exposure wasn’t just a product of the Industrial Revolution – it was part of our evolutionary landscape,” Joannes-Boyau stated. This suggests that our ancestors developed their brains under the influence of a potent toxic metal, potentially affecting their social behaviors and cognitive abilities.

Using advanced laser ablation mass spectrometry (LA-MS), the research team examined Neanderthal molars and other hominid fossils. The Neanderthal samples from Payre, France, dated to approximately 250,000 years ago, exhibited distinct lead “bands” that correspond to periods of high exposure during tooth development. Notably, lead was detected in 73% of the primate and hominid fossils tested, which originated from regions across Africa, Asia, and Europe. The findings indicate that Neanderthals consistently encountered lead, likely from natural geological sources, including lead-rich soil and volcanic dust.

These lead patterns were not due to contamination but matched biological growth layers, confirming that the metal was absorbed during the Neanderthals’ lifetimes. The researchers connected this ancient exposure to possible neurological consequences. In contemporary humans, lead is a recognized neurotoxin that can impair cognitive functions and social behavior.

The study explored the implications of lead exposure on the NOVA1 gene, which plays a crucial role in neuronal function. The NOVA1 gene manages how other genes are utilized in neurons, controlling a process known as alternative splicing. Disruption of NOVA1 activity has been linked to various neurological conditions, including autism and schizophrenia. When lead was introduced to human brain organoids with the archaic version of NOVA1, researchers observed disruptions in FOXP2, a gene vital for speech and language development.

Interestingly, the modern human version of NOVA1 appeared more resilient to lead-induced neuronal stress. This suggests that early exposure to lead may have driven genetic adaptations in modern humans, potentially enhancing their social and communicative capabilities compared to Neanderthals. “These results suggest that our NOVA1 variant may have offered protection against the harmful neurological effects of lead,” remarked Professor Alysson Muotri from the School of Medicine at UC San Diego.

The implications of this research extend beyond evolutionary biology. Professor Manish Arora from the Icahn School of Medicine at Mount Sinai underscored the significance of understanding how environmental exposures have shaped human evolution. The study offers a fresh perspective on how toxic exposures could influence survival advantages among species.

Published in the journal Science Advances, this research underscores the complex interplay between environmental factors and human development, providing new insights into the historical impacts of lead exposure on our ancestors. As scientists continue to explore these connections, the findings may enhance our understanding of contemporary health issues linked to environmental toxins.