Andean Residents Evolved Genetic Tolerance to High-Arsenic Water
Research indicates that populations in the Argentinian Andes have evolved a specific genetic variant that allows them to safely metabolize high levels of arsenic in their drinking water. This adaptation, centered on the AS3MT gene, helps convert toxic arsenic compounds into forms that are easily excreted, providing a survival advantage in regions where water arsenic levels are 20 times the World Health Organization limit.
Key points
- A 2015 study led by Carina Schlebusch and Lucie Gattepaille identified a protective gene variant near AS3MT in residents of San Antonio de los Cobres, Argentina.
- The town’s groundwater contained approximately 200 micrograms of arsenic per liter before 2012, far exceeding the WHO recommended limit of 10 micrograms per liter.
- The genetic variant helps the body produce less of the toxic intermediate monomethylated arsenic and more of the easily excreted dimethylated arsenic.
- A 2025 University of Chicago study found additional gene clusters, FMO and GSTO, in Bangladesh that also influence arsenic metabolism efficiency.
- The adaptation likely developed over thousands of years of exposure, as the region has been inhabited for at least 7,000 years.
Background
This finding builds on broader research into human genetic adaptation to environmental stressors. Recent studies, such as those detailed in our archive regarding Ice Age migration and neural development, highlight how genetic markers can reveal deep evolutionary histories and survival mechanisms. While those studies focused on brain development and ancient DNA, the arsenic tolerance research demonstrates how long-term exposure to toxic chemicals can drive specific genomic changes in human populations, similar to adaptations seen in other extreme environments.
Why it matters
Understanding genetic tolerance to arsenic offers insights into how human populations adapt to environmental toxins, potentially informing public health strategies in areas with high natural arsenic levels. It also highlights the role of natural selection in shaping human biology in response to local hazards.
What to watch
Further research may explore the prevalence of these genetic variants in other Andean populations and assess their impact on long-term health outcomes. Additionally, studies like the 2025 Bangladesh research may identify more gene clusters involved in arsenic metabolism, broadening our understanding of human adaptation to toxic chemicals.
Want the full story? Read the original reporting
Read on ScienceAlert