“We stopped using lead in our daily lives when we realized how toxic it is, but nobody had ever studied lead in prehistory,” said corresponding author Alysson Muotri, Ph.D., professor of pediatrics and cellular & molecular medicine at UC San Diego School of Medicine, associate director of the Archealization Center and director of the Sanford Integrated Space Stem Cell Orbital Research Center.
Surprisingly, teeth from people born between the 1940s and 1970s — when children were exposed to leaded gasoline and paint — showed similar patterns of lead exposure to fossilized human teeth.
The team hypothesizes that, like the Romans, ancient humans and other hominids may have been exposed to lead because of their need for water.
“One possibility is that they were looking for caves with running water inside,” Muotri said. “Caves contain lead, so they were all contaminated. Based on the tooth enamel studies, it started very early in infancy.”
Lead exposure impedes brain development, leading to deficits in intelligence and difficulties with emotional regulation.