Today, lead exposure directly correlates with the post-industrial world. However, new evidence indicates that exposure to the toxic element is not necessarily a new problem. Based on an interdisciplinary approach to geoarchaeological analysis, wise man and our hominid ancestors struggled with leadership for over two million years. According to a study published Oct. 15 in Achievements of scienceThe effects of lead are so widespread that they may have influenced the evolution of the human brain, behavior and even our language. Moreover, our ability to withstand some worst effects of metal may also partly explain how we outlived our cousins, Neanderthals.
State of Leadership Today
Lead exposure remains a public health problem worldwide, even after decades of efforts to correct the situation. According to Institute for Health Metrics and EvaluationThis toxic metal is responsible for more than 1.5 million deaths worldwide in 2021. He also continues negatively influence physical and nervous development of children, which often leads to lower test scores, behavioral problems, hearing problemsAnd anemia.
Despite this knowledge, lead is still used in many car batteries, ceramics, cosmetics and other everyday items. Meanwhile, even drinking water can be contaminated due to lead leaching into water supplies through outdated plumbing systems.
Teeth tell a different story
For years, experts have largely agreed that lead exposure represents a near-modern crisis. completely tied to industrial projects including smelting, mining and long-term use of leaded gasoline. While this is partly true, an international team of archaeologists, geneticists and chemists believe that hominids consumed the metal at various times over millions of years.
Evidence comes from 51 fossilized teeth from wise man and Neanderthals, as well as ape species such as Australopithecus africanus And Strong Paranthropus. By analyzing the teeth using a technique known as precision laser ablation geochemistry, the researchers identified distinct “lead streaks” that formed inside the teeth as their dentin and enamel grew during each sample's childhood.
“Our data shows that lead exposure was not just a product of the Industrial Revolution – it was part of our evolutionary landscape,” Renaud Joannes-Boiau, head of the Geoarchaeology and Archaeometry Research Group (GARG) at Australia's Southern Cross University, said. says the statement.
Instead of lead paint or gasoline, millions of years ago exposure may have been caused by soil and water contamination, sometimes exacerbated by volcanic activity. The metal is even sometimes released from the body's own bone reserves during times of illness or stress.
“This means that our ancestors' brains developed under the influence of a potent toxic metal, which may have shaped their social behavior and cognitive abilities over thousands of years,” Joannes-Boillot added.
Brain organoids and NOVA1
To test how lead exposure might have affected evolutionary cognitive development, Joannes-Boiau and his colleagues turned to brain organoid experts. Brain organoids created by manipulating the growth of stem cells in the laboratory function as miniature models of the mind that scientists can use as a proxy to study the human brain. In this case, the researchers grew organoids to test the effects of lead on two variants of a gene associated with neurodevelopment called NEW1. Scientists have long known Homo sapiensthis is the version NEW1 different from NEW1 among Neanderthals and our other extinct relatives, but found no explanation for this feature.
One possible reason emerged soon after brain organoids were exposed to lead. In old examples NEW1the metal damages neurons in the cerebral cortex and thalamus, two areas of the brain largely responsible for the development of speech and language. But this disruption was not such a serious problem for organoids representing modern humans. NEW1 genes.
“Our work not only rewrites the history of lead exposure, but also reminds us that the interaction between our genes and the environment has shaped our species for millions of years and continues to do so,” Joannes-Boillot said.
With a better understanding of humanity's genetic pathway, researchers may be able to better mitigate the worst effects of lead exposure, especially during childhood development. The findings provide an “extraordinary example” of environmental influences driving evolution, said Alisson Muotri, a pediatric cell medicine researcher at the University of California, San Diego.
“In this case, lead toxicity may have caused genetic changes that improved survival and our ability to communicate using language,” explained the study's co-author, before cautioning that these same changes “now also influence our vulnerability to modern lead exposure.”
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