Ancient lead exposure may have influenced how our brains evolved

A study of fossil teeth suggests that prehistoric hominids were exposed to toxic lead for at least 2 million years, and modern humans may have evolved to cope with the toxic metal better than our ancient relatives.

Lead poisoning has long been considered a unique modern problem associated with industrialization, poor mining practices, and its consequences. use as a fuel additivewhich has been discontinued since the 1980s.

Particularly dangerous for children affecting their physical and mental development, but it can also cause a range of serious physical and psychological symptoms in adults.

Renaud Joan-Boillot from Southern Cross University in Lismore, Australia, and colleagues wanted to find out whether our ancient relatives were exposed to lead.

They analyzed 51 fossil hominid teeth, including Australopithecus africanus, Strong Paranthropus, Gigantopithecus black, Neanderthal man And wise man. The fossils were from Australia, Southeast Asia, China, South Africa and France.

The scientists looked for lead signals in the teeth using laser ablation, which revealed bands of lead absorbed by the teeth during periods of exposure when the hominids were still growing. This exposure could come from environmental sources such as contaminated water, soil, or volcanic activity.

Joannes-Boillot says the team was particularly surprised by the amount of separation in the teeth Gigantopithecus blackan ancient giant relative of modern orangutans that lived in the territory of modern China. “If a modern person had that much lead in their body, I would say that person had a lot of exposure from industry or human activities,” he says.

The team then examined whether there was any difference between how modern humans deal with lead versus how modern humans deal with lead. Neanderthals. Using lab-grown brain models called organoidsthey studied both the Neanderthal and human versions of a gene called NEW1 and tested the neurotoxicity of lead on organoids.

“What we see is modern NEW1 suffer much less from lead neurotoxicity,” says Joannes-Boiau.

The most important thing is when organelles with archaic NEW1 exposed to lead, another gene called FoxP2 was greatly disturbed.

“These genes are associated with cognition, language and social cohesion,” says Joannes-Boiau. “And for modern humans it is less neurotoxic than for Neanderthals, which would be a very big advantage wise man and implies that lead played a role in our evolutionary journey.”

But Smith asked from Griffith University in Brisbane, Australia, is unsure about the extent of lead exposure and whether the work on organelles can be extrapolated to an evolutionary advantage for modern humans.

“This is a really complex paper that makes some very speculative claims,” Smith says. “While it is not surprising to me that wild primates and ancient hominids were naturally exposed to lead, as we have published in numerous papers over the past seven years, the limited distribution, number and type of fossils included simply do not prove that human ancestors were continuously exposed to lead for 2 million years.”

Neanderthals, early humans and rock art: France

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