Summary of the Article: Ancient Lead Exposure & Human Brain Evolution
This article, published in Science Advances on October 15, 2025, details a groundbreaking finding: ancient hominids, including early humans and great apes, were exposed to lead much earlier than previously thought – up to two million years before the advent of mining. This long-term exposure is hypothesized to have considerably impacted brain evolution, possibly hindering the development of language and social skills in species except modern humans.
Key Findings:
* Widespread Lead Contamination: Analysis of fossilized teeth from 51 hominids across Africa, asia, and europe revealed lead traces in 73% of the samples, including 71% of modern and archaic human fossils.Gigantopithecus blacki fossils showed the highest levels of exposure,dating back 1.8 million years.
* Unexpectedly Early Exposure: This challenges the previous understanding that meaningful lead exposure began with the Romans and the Industrial Revolution. Researchers found similar lead patterns in teeth from people born during the mid-20th century (leaded gasoline/paint era) as in ancient fossils.
* Source of Exposure: The researchers suggest ancient hominids likely encountered lead while searching for water sources, notably in caves.
* Genetic Protection in Modern Humans: Modern humans possess a unique genetic variant in the NEW1 gene (neuro-oncological ventral antigen 1) that offers protection against the detrimental effects of lead on brain development.This variant differs by a single DNA base pair from the version found in Neanderthals.
* Impact of the NEW1 Variant: Brain organoid studies showed that the archaic NEW1 variant accelerated brain maturation but resulted in less complexity. Crucially, lead exposure altered NEW1 activity in both variants, but only the archaic variant impacted FOXP2, a gene vital for speech and language. This suggests the modern NEW1 variant provided a selective advantage by mitigating the negative effects of lead on language development.
In essence, the article proposes that chronic lead exposure acted as a selective pressure, favoring the evolution of a protective genetic variant in modern humans that allowed for more complex brain development and ultimately, the emergence of language and advanced social capabilities.
