For thousands of years, humans living high in the Argentinian Andes have relied on drinking water that would make most people deathly ill. There, naturally occurring arsenic in volcanic bedrock leaches into the groundwater, contaminating the local water supply with levels of the toxic metalloid that would pose serious health risks to most human populations. But for one group in northern Argentina, natural selection may have provided an unusual genetic advantage. According to a DNA analysis of

Tag-uri: DNA