Ancient Lead Exposure Influenced Neanderthal and Human Brain Development

Research has revealed that ancient lead exposure significantly influenced the evolution of Neanderthal and early human brains. A study led by researchers at Southern Cross University in Australia indicates that our ancestors were subjected to lead for at least two million years, challenging the long-held belief that lead toxicity is a modern phenomenon primarily linked to industrial pollution.

The groundbreaking findings show that lead exposure was integral to the evolutionary landscape of our ancestors, impacting their cognitive abilities and social behaviors. According to Professor Renaud Joannes-Boyau, co-corresponding author and Head of the Geoarchaeology and Archaeometry Research Group at SCU, “Our data show that lead exposure wasn’t just a product of the Industrial Revolution – it was part of our evolutionary landscape.”

To conduct their research, the team utilized laser ablation mass spectrometry (LA-MS), a sophisticated technique that allows for precise elemental and isotope analyses of solid materials. They examined Neanderthal molars and other hominid fossils, including samples from Payre, France, dating back approximately 250,000 years. Remarkably, 73% of the primate and hominid fossils tested across Africa, Asia, and Europe showed signs of lead exposure. These findings revealed distinct bands of lead within the teeth, indicating periods of elevated exposure during tooth development, likely from natural geological sources such as lead-rich soil and volcanic dust.

The researchers demonstrated that these lead patterns were not the result of later contamination, as they directly corresponded to biological growth layers in the teeth. This evidence points to the fact that Neanderthals were repeatedly exposed to lead while they were alive. Importantly, the study links this ancient exposure to potential neurological effects, as lead is recognized as a neurotoxin that can impair cognition, learning, and social behavior in modern humans.

The research also examined the NOVA1 gene, which plays a crucial role in neuronal function by regulating how genes are expressed in brain cells. Disruption of NOVA1 has been associated with neurological conditions, including autism and schizophrenia. When lead was introduced to human brain organoids—miniature brain models carrying a Neanderthal-like version of NOVA1—the gene FOXP2, essential for speech and language development, was adversely affected. Conversely, the modern human version of NOVA1 displayed greater resilience to lead-related neuronal stress, suggesting a potential evolutionary advantage.

According to Professor Alysson Muotri from the School of Medicine at UC San Diego, “These results suggest that our NOVA1 variant may have offered protection against the harmful neurological effects of lead.” This highlights how environmental pressures, such as lead toxicity, could have driven genetic changes that enhanced survival and communication abilities, while also impacting modern susceptibility to lead exposure.

The implications of this study extend beyond individual health, as noted by Professor Manish Arora from the Department of Environmental Medicine at the Icahn School of Medicine at Mount Sinai in New York. He emphasized that understanding how environmental exposures shaped evolution could offer new insights into the origins of disorders linked to such exposures.

Published in the journal Science Advances, this research underscores the need to reconsider the historical context of toxic exposure and its lasting impact on human evolution. As scientists continue to unravel the complexities of our ancestors’ lives, this study provides a compelling narrative of how environmental factors shaped the trajectory of human development over millennia.