We are used to considering lead as an enemy to health. And it is, without a doubt. But new research intoUniversity of California San Diego raises a fascinating question: what if this toxic metal, present in the environment millions of years ago, contributed to the development of human intelligence and language?
The study, published on October 15, 2025 on Science Advancestells a story that starts from afar. A journey into the fossils of extinct hominids and apes, showing how exposure to lead was already widespread at least two million years ago. And how, over time, Homo sapiens came to be genetically adapted to resist its effects. An adaptation that our brain may have made more complex, more connected, and above all more capable of communicating.
Analysis of fossil teeth
To understand how old lead exposure was, the researchers analyzed 51 fossilized teethcoming from Africa, Asia and Europe. These were remains belonging to different species: from ours more remote ancestors such as Australopithecusto the Neanderthalup to extinct giant apes like the Gigantopithecus blacki.
The most relevant data? 73% of the samples contained traces of leadincluding the 71% of human teethboth archaic and modern. Notably, the highest levels were found in a living G. blacki specimen 1.8 million years ago. A discovery that disproves the widespread idea that lead pollution only began with Roman pipes or modern industrialization.
As he explained Alysson Muotrigeneticist and lead author of the study, “our ancestors sought caves with running water, but many caves contain lead. So exposure was inevitable.” And it began already in the first years of lifeas shown by the marks left in the teeth.
Another interesting comparison emerged with the teeth of people born between the years 40s and 70s of the twentieth centurywhen paint and gasoline contained lead: Contamination levels were strikingly similar to those found in ancient fossils. A sign that environmental exposure has been a constant for millions of yearsalthough its consequences may not have always been negative.
The NOVA1 gene
Lead is known for its toxic effects on the nervous system: damages neuronshinders brain development and can impair cognitive abilities And social communication. Yet despite widespread exposure, Homo sapiens has developed superior mental abilities compared to its Neanderthal cousins. Why?
The key may be hidden in one genetic mutation occurred in NOVA1 gene. It is a gene involved in development of neurons and brain connectionsparticularly sensitive to lead exposure. The version present in modern humans it differs from that of Neanderthals by only one DNA letterbut this tiny variation makes a big difference.
To test the effect of this mutation, Muotri’s team used cerebral organoids – small brains grown in the laboratory – recreating both the modern and archaic versions of the gene. Result: brains with modern NOVA1 they grew more slowlybut in a way more articulated and with more robust connections. And above all, when exposed to lead, they resisted better to toxic effects.
That’s not all: researchers have found that only the archaeal version of NOVA1 interferes with the activity of the FOXP2 geneknown to be fundamental in language development. Although FOXP2 is identical in Neanderthals and Homo sapiens, is regulated differently based on the variant of NOVA1. In the ancient version, neurons related to communication result more vulnerable to cell death. A possible reason why Neanderthals, despite having abstract thinking, .
Language as an evolutionary superpower that changed the history of humanity
According to the study, the appearance of the modern version of the NOVA1 gene would have a huge impact on the survival of Homo sapiens. By allowing the development of a more complex language, our brain would have evolved to communicate better, collaborate more And build complex societiesas Muotri points out
Language changes everything. It is what allowed us to plan, to transmit knowledge, to adapt together.
And this “communication superpower” could explain why Neanderthals became extinctdespite having a brain of similar size to ours.
This discovery has not only historical value. The mechanisms discovered could in fact also help to understand better some language disorders and neurodevelopmental, such as autism or verbal apraxia. Studying the link between NOVA1 and FOXP2 could pave the way to new therapies targeted, based on genetics and the environment.
