For thousands of years, residents of the Argentine Andes, particularly in the town of San Antonio de los Cobres, have consumed water contaminated with high levels of arsenic, a toxic metalloid often fatal to most humans. However, DNA analysis indicates that this population has a genetic mutation likely allowing them to metabolize arsenic more safely.
Research led by Karina Schulbusch and Lucie Gattepaille from Uppsala University identifies a cluster of mutations near the AS3MT gene, which seems to help these individuals process arsenic more efficiently. They produce less of the toxic monomethylated arsenic (MMA) and more of the safer dimethylated arsenic (DMA), which is excreted easily.
Previously observed, this unique metabolic ability has puzzled scientists. Arsenic levels in San Antonio de los Cobres’ drinking water previously reached around 200 micrograms per liter—20 times the World Health Organization’s recommended limit of 10 micrograms. The town’s inhabitants have lived there for over 7,000 years, enabling natural selection to favor genetic traits that mitigate arsenic’s harmful effects.
The study, published in Molecular Biology and Evolution, suggests that genetic adaptation to high arsenic levels might not be limited to this population and could be occurring in other Andean groups as well. The findings underscore the remarkable adaptability of humans to toxic environmental conditions, potentially conferring a significant advantage for those living in arsenic-rich areas.
