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posted by cmn32480 on Thursday June 04 2015, @04:14PM   Printer-friendly
from the Darwin-would-be-proud dept.

The Scientist reports on a study of a villages in Argentina, where the people have been drinking poison—arsenic, to be specific—for thousands of years. The levels in the principal water source is up to 80 times the level considered to be safe by the World Health Organization (WHO). Even the best wells exhibit over 20 times the arsenic allowed in the WHO limit.

And it doesn't seem to bother them at all. There is every indication that these Andean communities may have evolved the ability to metabolize arsenic.

Swedish biologist Karin Broberg, of Stockholm’s Karolinska Institute, and colleagues at Uppsala and Lund Universities have been trying to figure out how generations of villagers in the Andean village of San Antonio de los Cobres (SAC), an area of nearly 6,000 residents, have been able to survive this chronic exposure to toxic levels of arsenic.

The researchers knew that a particular allele, AS3MT, located on chromosome 10, was suspected as the main gene involved in arsenic metabolism in humans. But the metabolism rate in these Andean villagers was sky high compared to people elsewhere.

Broberg and her colleagues hypothesized that the remarkable arsenic tolerance of SAC residents might be due to particular variants of AS3MT that confer better arsenic metabolism. They wondered, further, if thousands of years of arsenic exposure had given a survival advantage to individuals with these metabolism-driving alleles and had increased the frequencies of these genetic variants.

By comparing genetic samples and urine from a wide selection of South American populations in Peru, Argentina, and Columbia, they hoped to determine if the arsenic tolerance was simply due to genetic accident, (population drift) or if it was a byproduct of natural selection. Natural selection tends to exhibit itself via higher levels of homozygosity, where particular alleles come from one lineage. (See here for a primer on Drift vs Selection.

In the area around AS3MT, the SAC population differed dramatically from the comparison populations. Not only did the SAC women have higher levels of protective AS3MT alleles, but these alleles also had longer stretches of homozygosity—a telltale sign of selection.

The extremely strong difference in allele frequency is considered a clear result of selective pressure on a population.


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  • (Score: 2) by krishnoid on Thursday June 04 2015, @07:18PM

    by krishnoid (1156) on Thursday June 04 2015, @07:18PM (#192229)

    I wonder if you can use this as part of a proof of evolutionary theory mechanisms that creationists might accept. At the least, it would be interesting to see how it's incorporated/worked around.

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  • (Score: 0) by Anonymous Coward on Thursday June 04 2015, @07:49PM

    by Anonymous Coward on Thursday June 04 2015, @07:49PM (#192246)

    I wouldn't recommend that. The way they interpret this data is extremely strange. It doesn't appear to support their conclusions at all. Any creationist could just look at the data and laugh you out of the room. If this data is all it takes to convince people they are seeing natural selection something has gone seriously wrong:

    1) These levels of arsenic are not that toxic since only 70% of villagers had the 'protective' alleles
    2) The apparent protection provided by these alleles is extremely weak compared to unexplained differences in metabolism between towns
    3) Allele frequencies for this gene differed amongst control populations just as much as with this one.

    http://ehp.niehs.nih.gov/1205504/ [nih.gov]

  • (Score: 0) by Anonymous Coward on Thursday June 04 2015, @08:36PM

    by Anonymous Coward on Thursday June 04 2015, @08:36PM (#192259)

    This is, once again, a strawman. As has been pointed out repeatedly Darwin didn't even come up with the idea of natural selection and mutation. That idea was a 'creationist' concept, Darwin even cited Alfred Russel Wallace as the originator in his book on the origin of species. It's disingenuous to keep crediting Darwin with something he didn't come up with. Critics of 'evolution' don't question natural selection and random mutation they question universal common descent. To keep framing it differently and building a strawman when this has been repeatedly pointed out over and over shows how disingenuous you are. If you are going to tackle an issue tackle the issue not the strawman. The only thing Darwin did was take the idea of selection and mutation that he didn't even come up with and speculate that all species share a common ancestor. Unfortunately for him the evidence does not seem to support this.

    • (Score: 0) by Anonymous Coward on Friday June 05 2015, @01:10AM

      by Anonymous Coward on Friday June 05 2015, @01:10AM (#192327)

      This is, once again, a strawman.

      You're darn tootin' it is.

      As has been pointed out repeatedly Darwin didn't even come up with the idea of natural selection and mutation.

      And there it is! The strawman in full. This is completely irrelevant to anything.

      That idea was a 'creationist' concept, Darwin even cited Alfred Russel Wallace as the originator in his book on the origin of species. It's disingenuous to keep crediting Darwin with something he didn't come up with.

      Attribution is irrelevant to the truth of the matter unless the question of attribution is the centre of the matter. Here it is not.

      Critics of 'evolution' don't question natural selection and random mutation they question universal common descent.

      All of them? Or some, as is most convenient for you now?

      My ex- is a creationist. She's convinced that her fictional deity created the universe, the Earth, the animals, and the people, and her position is that nothing has changed since her big invisible skydaddy did so.

      To keep framing it differently and building a strawman when this has been repeatedly pointed out over and over shows how disingenuous you are.

      You argue like a politician, shifting the argument to a position you feel you can win: nobody mentioned Darwin until you did. The first strawman was constructed by you. You just continually use that particular term in an effort to reinforce your own somewhat hilarious position.

      If you are going to tackle an issue tackle the issue not the strawman.

      Correct. Stop it. Stop it now.

      The only thing Darwin did was take the idea of selection and mutation that he didn't even come up with and speculate that all species share a common ancestor.

      Here's your same old strawman again. Can't you dispense with that? Who came up with it is completely irrelevant to your stated position - that it is flawed:

      Unfortunately for him the evidence does not seem to support this.

      Unfortunately for him? I thought he didn't come up with it? Your position is that it was an idea from creationists, therefore it is unfortunate for them that the evidence doesn't support it.

      That is, if it actually doesn't. You've cited no information to support your conclusion nor have you have provided evidence besides a repeated statement that Darwinism was not created by Darwin therefore it is all false, without any explanation as to the relevance of the statement.

      You have not even constructed an argument.

      • (Score: 0) by Anonymous Coward on Friday June 05 2015, @06:20AM

        by Anonymous Coward on Friday June 05 2015, @06:20AM (#192389)

        My ex- is a creationist. She's convinced that her fictional deity created the universe, the Earth, the animals, and the people, and her position is that nothing has changed since her big invisible skydaddy did so.

        According to the bible, God made exactly two humans, Adam and Eve, and all other humans are their descendents. However there are clearly very different humans (black skinned, white skinned, red skinned, etc.) and those traits are obviously inherited (children of black people are black again, etc.). Therefore it is impossible that nothing changed since God created the world. Well, unless the bible doesn't tell us the truth. ;-)

        • (Score: 2) by TK on Friday June 05 2015, @01:47PM

          by TK (2760) on Friday June 05 2015, @01:47PM (#192523)

          See the Curse of Ham [wikipedia.org] and the Mark of Cain. [wikipedia.org] Bonus: Towel of Babel [wikipedia.org] for the origin of world languages.

          The Mormons claimed that Native Americans were red-skinned because God cursed them too. I don't know the name of that story though.

          --
          The fleas have smaller fleas, upon their backs to bite them, and those fleas have lesser fleas, and so ad infinitum
    • (Score: 2) by bob_super on Friday June 05 2015, @01:22AM

      by bob_super (1357) on Friday June 05 2015, @01:22AM (#192330)

      > Critics of 'evolution' don't question natural selection and random mutation they question universal common descent.

      Adam, please meet Eve, go populate the earth. We all descend from the same patch of Heaven clay, according to The Book.
      I'm special, my God made me in Her image and it took a whole day, when She whipped up all the rest of creation in barely more time. Or maybe She didn't make me directly, but She made sure I'd figure out how to evolve in Her image from dumb apes, so that She might love me the most and I could rule the Earth.

      More seriously though (not an easy task on this topic), I have not read "the evidence that doesn't seem to support" the idea that essentially all lifeforms on earth have eerie similarities. I would be glad to get some pointers.

  • (Score: 3, Informative) by kurenai.tsubasa on Thursday June 04 2015, @10:28PM

    by kurenai.tsubasa (5227) on Thursday June 04 2015, @10:28PM (#192285) Journal

    Unfortunately, you can't, if you're referring to young earth creationists. They fully acknowledge that natural selection can cause small differences, i.e. petri dish experiments with e. coli. I imagine this would be similar. Instead they have a concept called “kinds” that allows for genetic changes. “Kinds” are essentially species although sometimes I think it can operate at the genus level. They dispute the idea that natural selection can lead to new species or “kinds.”

    The Wikipedia article on theistic evolution [wikipedia.org] has a summary of that viewpoint along with other kinds of creationism. The most interesting to me is creationists that stretch the meaning of a “day” in Genesis to be some kind of logarithmic scale (or exponential?) that varies from several billions of years for the first days then goes down to millions of years for the next few days. Concordantly, they believe that although natural selection can lead to speciation, their god set it all in motion and guided it so the end result was a creature in god's image.

    • (Score: 0) by Anonymous Coward on Friday June 05 2015, @06:26AM

      by Anonymous Coward on Friday June 05 2015, @06:26AM (#192390)

      Concordantly, they believe that although natural selection can lead to speciation, their god set it all in motion and guided it so the end result was a creature in god's image.

      Well, I don't see a problem with that view. It doesn't contradict anything we can decide with science (after all, "random" just means "we can't see a regularity", therefore it is completely consistent that some random events are actually god-decided). Things only get problematic if people deny scientific results in order to protect their believes. As long as they are adapting their believes to the scientific results, everything is OK (well, at least in that respect; their belief might still have bad consequences otherwise).

      • (Score: 2) by kurenai.tsubasa on Saturday June 06 2015, @12:49AM

        by kurenai.tsubasa (5227) on Saturday June 06 2015, @12:49AM (#192730) Journal

        I don't see a problem really, either, other than Occam's razor, which is why I find it interesting. It's plausible, and as we know, absence of evidence is not evidence of absence. Of course, then, there's the problem with figuring out who makes the watchmaker. It's probably just turtles all the way down.

        What is the nature of the prime mover? Is there even a prime mover? What would it mean if there were no prime mover? Aristarchus, help!