Humans in The Andes Seem to Have Evolved an Unusual Genetic Ability

Key Points:

• Researchers have identified a gene variant in a population from the Argentinian Andes that helps metabolize arsenic more safely, likely as a result of natural selection due to long-term exposure to arsenic-contaminated groundwater.
• The town of San Antonio de los Cobres had drinking water with arsenic levels about 20 times higher than the WHO recommended limit until 2012, yet inhabitants have lived there for thousands of years without typical arsenic-related health issues.
• Genetic analysis revealed that variants near the AS3MT gene, which influences arsenic metabolism, are far more common in this Argentinian population compared to similar groups in Peru and Colombia, indicating a localized genetic adaptation.
• Additional research from Bangladesh identified other gene clusters (FMO and GSTO) that also affect arsenic metabolism, suggesting multiple genetic pathways may contribute to arsenic tolerance in different populations.
• These findings provide rare evidence of human adaptation to a toxic chemical and suggest that genetic tolerance to arsenic exposure may be more widespread among Andean populations with prolonged exposure.