Study Identifies First-Ever Human Population Adaptation to Toxic Chemical, Arsenic

Karin Broberg, EurekAlert, March 3, 2015

High up in the high Andes mountains of Argentina, researchers have identified the first-ever evidence of a population uniquely adapted to tolerate the toxic chemical arsenic.

For thousands of years, in some regions of the Andes, people have been exposed to high levels of arsenic, a naturally occurring phenomenon that happens when arsenic in the volcanic bedrock is released into the groundwater. How could this population adapt to tolerate arsenic, a potent killer of such ill repute that it’s often the overused plot-driver of many murder mysteries?

In a new study published in the advanced online edition of Molecular Biology and Evolution, a Swedish research team led by Karolinska Institutet and Uppsala University professor Karin Broberg, performed a genome wide survey from a group of 124 Andean women screened for the ability to metabolize arsenic (measured by levels in the urine). The study pinpointed a key set of nucleotide variants in a gene, AS3MT, which were at much lower frequencies in control populations from Columbia and Peru. The researchers estimate that the increase in frequency of these variants occurred recently, between 10,000-7,000 years ago, based on the age of a recently excavated mummy that was found to have high arsenic levels in its hair.

Thus, this Andean population has adapted to their environment through increased frequencies in protective variants against a toxicant. The set of AS3MT nucleotide variants, harbored on chromosome 10, were distributed worldwide, with the highest frequencies in Peruvians, Native Americans, Eastern Asia and Vietnam. The authors speculate that the forces driving the local adaptation may have occurred as a result of the severe health effects of arsenic, which is most toxic to young children and those in their reproductive prime, and the need for faster metabolizers of arsenic, which may have been a matter of life or death in ancient times.

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  • MrBiIIGoode .

    Another argument I can use against the environmentalist nuts.

    • WR_the_realist

      How? The fact that people can evolve a degree of immunity to a toxin hardly proves that the toxins are benign. After all, that process of evolution means that many children with insufficient immunity have to die — evolution doesn’t work unless inadequate genes are selected out, and that means dead kids.

      • MrBiIIGoode .

        People dying is how we got to where we are in the present form. The point is that we cannot destroy all life on this planet, even if one was to turn the oceans into a garbage dump, new species of life would evolve that thrives in garbage.

        • WR_the_realist

          We can certainly destroy much of the life that is beautiful or fascinating. Humans are perfectly capable of driving whales and many other mammal or bird species to extinction. OTOH, we will always have bacterial slime and cockroaches, I can agree with that.

  • Zimriel

    Arsenic helped propel the Andeans into the Bronze Age. Arsenic with copper hardens it; since it often happens by accident, this is considered the first stage into learning about alloys. Even the Maya and Aztecs didn’t ever figure it out on their own.

    Arsenic also did… strange things to their culture. Peter Watson, “The Great Divide” explains just how alien.

    • Reynardine

      How much use did they make of their bronze technology, however? From what I understand, serious metallurgy (and the wheel), though the means were completely available, was passed up by central and south American cultures.

      • Zimriel

        Apologies in advance for the textwall –
        Hiram Bingham (1911): “However, it is reasonably certain that the Inca builders used powerful little bronze crow-bars to get those ashlars in place which were too heavy to be lifted by hand. Called champis, these bars were sufficiently strong to be used in adjusting blocks of stone weighing ten or twenty tons. In a tensile test, made under the direction of Professor Matthewson, an old Inca champi of poor quality showed an ultimate strength of 28,000 pounds to the square inch. We found by experiment with a new bronze crow-bar of the same Inca metallurgists, it had still greater strength. The Incas could have used their little crow-bars for prying into place granite blocks weighing twenty tons without damaging the champis.”

        If you grab a segment of text from that, you can google and read the whole article. It seems the Andeans used bronze in every way they could think of (except, sadly for them, for making pens).

        1911 would be before the age of Political Correctness – indeed before WW1 – so when a white professor then is admiring a foreign culture, he’s doing it because he finds something worthy of admiration.

        • Reynardine

          Fascinating, and duly noted!

          The admiration of a foreign culture meant something back then, as it showed something that our ancestors actually considered as being laudable.

          I miss such standards for scholarship when we studied cultures to understand what made them successful instead of the slavish pluralist worship thereof.

          • LHathaway

            I realize for the last 60 years or so, our leaders have taught us to believe that which is not just untrue, but that which is diametrically opposite of the truth. . but what actual era would that have been, when information wasn’t used to manipulate us? And indeed, was not, for them most part, invented itself for just that purpose? Where would that actually be?

  • John Smith

    This was also common in parts of Austria – Styria, IIRC – where the locals (“Arsenic Eaters”) intentionally took small doses gradually increased until they built up immunity because it improved their complexion and was believed to improve health because of that.