When we think of lead poisoning, most of us imagine modern human-made pollution, paint, old pipes, or exhaust fumes.
When we think of lead poisoning, most of us imagine modern human-made pollution, paint, old pipes, or exhaust fumes.
But our new study, published today in Science Advances, reveals something far more surprising: our ancestors were exposed to lead for millions of years, and it may have helped shape the evolution of the human brain.
This discovery reveals the toxic substance we battle today has been intertwined with the human evolution story from its very beginning.
It reshapes our understanding of both past and present, tracing a continuous thread between ancient environments, genetic adaptation, and the unfolding evolution of human intelligence.
Lead is a powerful neurotoxin that disrupts the growth and function of both brain and body. There is no safe level of lead exposure, and even the smallest traces can impair memory, learning and behavior, especially in children. That’s why eliminating lead from petrol, paint and plumbing is one of the most important public health initiatives.
Yet while analyzing ancient teeth at Southern Cross University, we uncovered something wholly unexpected: clear traces of lead sealed within the fossils of early humans and other ancestral species.
These specimens, recovered from Africa, Asia and Europe, were up to two million years old.
Using lasers finer than a strand of hair, we scanned each tooth layer by layer—much like reading the growth rings of a tree. Each band recorded a brief chapter of the individual’s life. When lead entered the body, it left a vivid chemical signature.
These signatures revealed that exposure was not rare or accidental; it occurred repeatedly over time.
Our findings show that early humans were never shielded from lead by the natural world.
