Surviving an Andean wasteland with genetic tolerance to arsenic

San Antonio de los Cobres is a place in Argentina sitting 12,000 feet above sea level, on dry volcanic rock. The environment is roughly as welcoming as a Mars's wasteland, except that the people there do at least
have water, but poisoned by a heavy arsenic concentration. Research has shown that people in the San Antonio de los Cobres area have remarkable developed a mutation in their genes to cope with the high levels of Arsenic in the area.

Therefore, the people of San Antonio de los Cobres set about evolving humanity's first known adaptation to a toxic chemical. With at least 7000 years of generational practice, they're now grow accustomed to their poisoned H2O that they can withstand its arsenic concentration.

In normal circumstances (I mean, without these awesome genes), metallic arsenic accumulates in the body, causing convulsions, coma, and cancer. But the genetic mutation has given their livers the ability to detoxify arsenic much more efficiently than regular people and expel it right out of their bodies.

This proves the adaptation's potential of humankind under extreme situacion. Now I wonder how the first generation of these people managed to cope with poisoned water.

 

My uneducated guess is they didn't, maybe their ancestors lived initially at the edge of the wasteland and contacted the poisoned water seldom enough not to die quickly, but often enough that higher immunity to arsenic would be an advantage. As the 7000 years passed, natural selection would do its work, and those with improved immunity moved to claim the uninhabited poiosonous area.