A recent study reveals that exposure to lead significantly influenced the evolution of Neanderthal and early human brains over the past two million years. Conducted by researchers at Southern Cross University in Australia, the study challenges the long-held belief that lead poisoning is primarily a modern issue related to industrial pollution.
The research team analyzed the teeth of ancient primates and early humans, uncovering evidence that lead exposure has been a persistent factor in human evolution. According to Professor Renaud Joannes-Boyau, co-corresponding author and Head of the Geoarchaeology and Archaeometry Research Group (GARG) at SCU, “Our data show that lead exposure wasn’t just a product of the Industrial Revolution – it was part of our evolutionary landscape.” This insight suggests that the cognitive abilities and social behaviors of our ancestors may have been shaped by exposure to this toxic metal.
Using advanced laser ablation mass spectrometry (LA-MS), the researchers conducted high-precision analyses of Neanderthal molars and other hominid fossils. The samples from Payre, southern France, dating back approximately 250,000 years, revealed distinct bands of lead within the teeth. Notably, lead exposure was found in 73% of all primate and hominid fossils tested across Africa, Asia, and Europe.
These bands correlate with periods of high lead exposure during tooth formation, indicating repeated exposure to lead, likely from natural geological sources such as lead-rich soil or volcanic dust. The findings also show that this ancient lead exposure was not a result of later contamination, as the patterns matched biological growth layers, confirming absorption during the individuals’ lifetimes.
The research links lead exposure to potential neurological effects. In modern humans, lead is recognized as a neurotoxin that can impair cognition, learning, and social behavior. The NOVA1 gene plays a crucial role in regulating how other genes function in neurons. It influences a process called alternative splicing, which allows one gene to produce multiple protein variants. Disruption of NOVA1’s activity has been associated with neurological conditions such as autism and schizophrenia.
In experiments with human brain organoids—often referred to as “mini-brains”—the researchers introduced lead to organoids that carried the archaic Neanderthal-like version of NOVA1. They observed that lead exposure disrupted the FOXP2 gene, which is essential for speech and language development. Interestingly, the modern human variant of NOVA1 demonstrated greater resistance to lead-related neuronal stress, suggesting that modern humans may have evolved enhanced resilience to environmental toxins.
The implications of this study extend beyond neurobiology. As Professor Alysson Muotri from the School of Medicine at UC San Diego noted, “These results suggest that our NOVA1 variant may have offered protection against the harmful neurological effects of lead.” This presents an extraordinary example of how environmental pressures, such as lead toxicity, could have driven genetic adaptations that improved survival and communication abilities.
Professor Manish Arora, from the Department of Environmental Medicine at the Icahn School of Medicine at Mount Sinai in New York, emphasized the broader significance of the findings. “This study shows how our environmental exposures shaped our evolution,” he stated. The observation that toxic exposures can offer survival advantages encourages new perspectives in environmental medicine, particularly regarding the evolutionary roots of disorders linked to environmental toxins.
This important research was published in the journal Science Advances, contributing valuable insights into the complex interplay between environmental factors and human evolution. The study underscores the need for continued exploration into how ancient exposures have left lasting impacts on our biology and behaviors.
