Would you have guessed? This metal has been harming the human body for 2 million years
According to experiments conducted by an Australian research team, a metal that still frequently occurs today and is considered dangerous may have had a severely harmful effect on the health of Neanderthals and other early human ancestors.
When the term caveman comes up, many people immediately picture the Neanderthal. We know quite a lot about this ancient relative of ours — fossil evidence reveals much about both their physical features and their way of life. However, a recent study has shed light on a surprising factor that may have contributed to the extinction of the Neanderthals: a substance that not only poses a threat in the modern world but may have affected human health millions of years ago as well, reports Live Science.
Lead poisoning is nothing new
According to findings by a group of Australian researchers, lead has existed in the environment of humans and their ancestors in its natural form for more than two million years, carrying serious health risks. In large quantities, it damages the central nervous system and other vital organs, and it can also cause behavioural and learning disorders, particularly in children.
This might be surprising, as metal poisoning — especially lead poisoning, typically associated with old paints and building materials — is usually thought of as a modern issue. It seems almost hard to imagine that such substances could have harmed our ancient ancestors as well.
According to Renaud Johannes-Boyau, a researcher at an Australian university, phenomena such as prolonged drought, food and water scarcity, or exposure to toxins have a dual nature. While they threaten a species’ survival, they also drive natural selection and enhance adaptability.
They examined tooth remains
During their research, scientists compared 51 different tooth samples, looking for signs of lead contamination. The samples ranged in age from roughly 100,000 to nearly 2 million years old and came from a variety of hominin species — including Homo sapiens, Neanderthals, Australopithecus africanus, and even the extinct ape species Gigantopithecus blacki.
Lead was detected in more than 70% of the samples, sometimes in small amounts, sometimes in larger concentrations. According to Johannes-Boyau, even minimal exposure could have had a significant effect on the development of the nervous system and the later brain function of children in particular.
It may have influenced the development of speech
To test their hypothesis, the researchers created brain-modelling organoids — some of them simplified mini-brains, others full-scale complex models. Each model contained a version of the NOVA1 gene, a gene whose special variant plays an important role in the development of speech but existed in a more primitive form in most ancestral human genomes.
During the experiments, the modern variant of the NOVA1 gene showed much greater resistance when exposed to lead than its earlier versions. In Homo sapiens, NOVA1 plays a crucial role in the function of another gene, FOXP2, which is directly responsible for speech production. Even under lead poisoning, this interaction remains stable and effective.
However, in earlier human species, this protective mechanism did not exist — providing yet another example of natural selection at work, through which Homo sapiens gained a biological advantage over its predecessors.
Questions still remain
Although the experiments clarify the interaction between lead and the two mentioned genes, many questions remain unanswered. As Debbie Guatelli-Steinberg, an anthropologist at Ohio State University, pointed out, it is still unclear how such large amounts of lead could have been present in the environment of Neanderthals and other early humans, or how it entered their bodies in such significant quantities.