Recent analysis of teeth from two Neanderthal children dating back about 250,000 years ago suggests that both children might have been exposed to lead while they were still alive.
As documented in a study published Wednesday in the journal Science Advances, an international team of researchers compared the Neanderthal teeth with a specimen from a modern human child from about 5,000 years ago, with all three fossils collected from the same archaeological site in southeastern France. According to Phys.org, the discovery represents the earliest proof of lead exposure detected in hominid populations.
"Traditionally, people thought lead exposure occurred in populations only after industrialization, but these results show it happened prehistorically, before lead had been widely released into the environment," said study co-author Christine Austin, an assistant professor at the Icahn School of Medicine's Department of Environmental Medicine and Public Health, as quoted by CNN.
"Our team plans to analyze more teeth from our ancestors and investigate how lead exposures may have affected their health and how that may relate to how our bodies respond to lead today."As explained by Phys.org, Austin and her fellow researchers used laser techniques to measure levels of lead, oxygen, and barium in the Neanderthal teeth as they searched for markers of important events in the children's lives, such as nursing, weaning, chemical exposure, and reactions to climate change. Much like trees develop rings as they grow, teeth develop new layers each day during a child's growing-up years, and record changes to the environment that take place during that time. The researchers discovered signs of short-term lead exposure during the winter months, noting that this might have been because the children consumed tainted food or water, or inhaled smoke from fires that contained lead. Additionally, it was found that one of the children was born in the spring and that both children experienced more extreme temperature shifts than the modern human child whose tooth was analyzed for comparison purposes.
"[The lead] must have come from natural deposits in the area, whether they were going into an underground environment or they were eating contaminated food that was incorporated into their growing bones and teeth," said study lead author Tanya Smith, an associate professor at Griffith University.
In addition to the evidence of lead exposure, the researchers concluded that one of the Neanderthal children ingested milk through breastfeeding, based on trace levels of barium found in the growth rings. According to CNN, the child is believed to have nursed for about two-and-a-half years, much like modern human children who grew up in hunter-gatherer communities.
Study co-author Manish Arora, vice chairman of the Department of Environmental Medicine and Public Health at the Icahn School of Medicine, explained in a statement that his team's findings can still be relevant in present times because understanding the evolution of breastfeeding could "help guide the current population" on ideal breastfeeding practices. He added that the researchers are hoping to apply the techniques they used to determine how breastfeeding could affect the health of modern-day populations in a variety of ways, including heart health and neurodevelopment.