Human Ancestors Were Exposed to Lead Millions of Years Ago, and It Shaped Our Evolution

The toxic substance we battle today has been intertwined with the human evolution story from its very beginning, a new study has revealed. Researchers found clear traces of lead sealed within the fossils of early humans and other ancestral species, with some specimens dating back up to two million years. This discovery reshapes our understanding of both past and present, tracing a continuous thread between ancient environments, genetic adaptation, and the unfolding evolution of human intelligence.

Key Takeaways:

• The study found that early humans were exposed to lead repeatedly over time, with lead entering the body leaving a vivid chemical signature in fossil teeth.
• The lead found was not from mining or smelting, but from natural sources such as volcanic dust, mineral-rich soils, and groundwater flowing through lead-bearing rocks in caves.
• Researchers used stem cells to grow tiny versions of human brain tissue, called brain organoids, to understand how ancient exposure might have affected brain development.
• The brain organoids with an archaic, extinct version of a gene similar to what Neanderthals and Denisovans carried showed clear signs of stress and disrupted neural connections, while the modern-gene organoids were more resilient.
• The environmental stress may have been one of the unseen forces that sculpted the human story, favoring genes that strengthened our brains against environmental stress.
• Our discovery shows human biology evolved in a world full of chemical challenges and gives new context to a very modern problem, lead poisoning remains a global health issue.

Statistics:

• The study found lead exposure was not rare or accidental, but occurred repeatedly over time.
• The UNICEF estimates that one in three children worldwide still have blood lead levels high enough to cause harm.
• The researchers used lasers finer than a strand of hair to scan each tooth layer by layer, a process much like reading the growth rings of a tree.
• The brain organoids were given a realistic amount of lead, what ancient humans might have encountered naturally.

Sources:

• The Conversation -- Global Perspectives -- By Renaud Joannes-Boyau, Professor in Geochronology and Geochemistry, Southern Cross University
• Science Advances
• https://theconversation.com/human-ancestors-were-exposed-to-lead-millions-of-years-ago-and-it-shaped-our-evolution-267318
• UNICEF

[The author of this analysis is licensed in New Zealand and holds a Master of Technology - IT (Data Science) credential.]