A recent study suggests that ancient humans may have gained a survival advantage over other species due to their ability to better resist the harmful effects of lead exposure. An international research team examined the lead content in 51 fossilized hominid teeth, with the oldest samples dating back approximately 1.8 million years. The analysis revealed that 73% of these samples, which included Homo sapiens, Neanderthals, and other extinct Homo species, showed signs of lead exposure.

The researchers propose that Homo sapiens evolved to respond more effectively to lead exposure compared to Neanderthals, who went extinct around 40,000 years ago. Lead exposure is known to be linked to various health issues in humans, such as cardiovascular disease, learning disabilities, and even criminal behavior. While modern sources of lead exposure, like fossil fuels and lead-based paints, are well-documented, the study indicates that ancient hominids also faced similar risks.

According to the study, environmental factors such as volcanic emissions, wildfires, and erosion contributed to lead accumulation in certain areas, particularly affecting waterways. The researchers noted a significant difference in the brains of Homo sapiens and Neanderthals that may have influenced their responses to lead exposure. Both species shared a gene called NOVA1, but they possessed different versions of it.

To investigate this further, scientists created brain organoids—miniature brain models derived from stem cells—using the NOVA1 version found in modern humans and those from ancient hominids, including Neanderthals. The study found that lead exposure disrupted the activity of another gene, FOXP2, which is essential for the development of speech and language abilities. This disruption may have provided Homo sapiens with an evolutionary advantage over Neanderthals.

While the researchers acknowledge limitations in their study, such as the simplified nature of brain organoids compared to fully developed human brains, they conclude that the fossil, cellular, and molecular evidence supports the idea that lead exposure may have influenced social and behavioral functioning during evolution. This, in turn, likely afforded modern humans a survival advantage over their extinct relatives.