Ancient Lead Exposure Influenced Human and Neanderthal Brains

A groundbreaking study reveals that lead exposure significantly influenced the brain development of both Neanderthals and early humans for millions of years. Contrary to the belief that lead toxicity is a modern issue related to industrial pollution, researchers from Southern Cross University in Australia have found evidence of lead exposure dating back at least two million years.

The study, published in the journal Science Advances, analyzed ancient primate and human teeth, demonstrating that lead presence was a long-standing environmental factor affecting cognitive evolution. “Our data show that lead exposure wasn’t just a product of the Industrial Revolution – it was part of our evolutionary landscape,” stated Professor Renaud Joannes-Boyau, the study’s co-corresponding author and Head of the Geoarchaeology and Archaeometry Research Group at SCU.

Using laser ablation mass spectrometry, the researchers examined Neanderthal molars and other hominid fossils, including samples from Payre, France, dated to around 250,000 years ago. The analysis revealed distinct bands of lead within the teeth, indicating repeated exposure during tooth development. In fact, lead was found in 73% of the primate and hominid fossils tested, originating from geological sources such as lead-rich soil and volcanic dust, as well as water from the limestone environment of the Rhone Valley.

These findings suggest that the lead exposure experienced by Neanderthals and their ancestors could have had lasting effects on their neurological development. In modern humans, lead is recognized as a neurotoxin that can impair cognitive functions, learning, and social behavior. Researchers linked this ancient exposure to potential neurological consequences, particularly involving the NOVA1 gene, which regulates gene expression in neurons.

When the team introduced lead to human brain organoids—miniature brain models containing the archaic Neanderthal-like version of NOVA1—they observed disruptions in the FOXP2 gene, critical for language and speech development. The modern human version of NOVA1 displayed greater resilience to lead-related neuronal stress, suggesting that evolutionary adaptations allowed modern humans to better withstand environmental toxins.

Professor Alysson Muotri from the School of Medicine at UC San Diego remarked, “These results suggest that our NOVA1 variant may have offered protection against the harmful neurological effects of lead.” This adaptation could indicate that environmental pressures, such as lead toxicity, drove genetic changes that enhanced survival and communication capabilities, potentially giving modern humans an advantage over Neanderthals.

The implications of the study extend beyond evolutionary biology. According to Professor Manish Arora from the Department of Environmental Medicine at the Icahn School of Medicine at Mount Sinai in New York, “This study shows how our environmental exposures shaped our evolution.” He emphasized the importance of examining the evolutionary roots of disorders linked to environmental factors.

As scientists continue to explore the impact of ancient environmental exposures, this research underscores the complex interplay between our ancestors and their surroundings. The findings challenge long-held beliefs about lead toxicity and offer new insights into how ancient challenges may have shaped human evolution.