Two New Studies, Published in Science, Find No Evidence of Arsenic Life

By Veronique Greenwood | July 9, 2012 11:32 am

A year and a half ago, NASA announced that one of its scientists, Felisa Wolfe-Simon, had found a bacterium that could use arsenic instead of phosphorus in its DNA. This revelation, published in Science, had enormous implications for our understanding of what’s necessary for life—we’ve always thought phosphorus was essential and arsenic poisonous, and having that disproven might mean life could exist in environments where it had been thought impossible.

Almost immediately, though, scientists and science journalists began to pick apart this paper. DISCOVER blogger Carl Zimmer rounded up the case against in a Slate article shortly after the paper’s publication. Ever since, he’s kept track of the story’s evolution—including experiments posted by microbiologist Rosie Redfield on her blog that provided evidence against the claimhere on his blog.

All the way along, Wolfe-Simons refused to comment on Redfield’s experiments, saying she would wait until they were published by a peer-reviewed journal. Now, Redfield’s paper and one other paper finding no evidence of arsenic life have been published by Science, the same journal that published the original claim. The researchers found no evidence of arsenic being used in the bacterium’s DNA.

The authors note that it can survive at very low concentrations of phosphorus and can handle concentrations of arsenic an order of magnitude higher than other cells, which is neat, but not evidence that it can actually use arsenic–chemical tests showed that there was no arsenic in the bacterium’s DNA. Wolfe-Simons, now open to talking about the work, said something very peculiar in corresponding with Alan Boyle of MSN: “There is nothing in the data of these new papers that contradicts our published data.” It’s hard to see how she can think that; however, she and her collaborators appear to be alone in that conviction.

For more, check out Carl’s live-blog of Redfield’s talk about the work at a recent conference.

  • scribbler

    So, will all those who defended this now eat their spiteful, condescending words? Well, only those who spoke them, of course…


  • Sunny D

    Why is science so complicated? Makes me wonder what happens when some claim like this ISN’T carefully reviewed…

    Perhaps we live our lives on some false claims. Not a good thing.

  • Cjadavis

    This is the reason why science is so awesome. The reason being that every theory out there gets “picked apart” and then stands against experimental trial. This is how we can be reasonably certain about our assumptions in science, because there is a great community of scientists out there who need statistical, or direct evidence to back up their claims. Thankfully there are many people who work out these issues for your average joe or jill so he or she can support their knowledge base on concrete evidence and not some poorly supported theory. It is sad that this breakthrough would be a more celebrated by the public if the research did suggest “arsenic life”. To me it is a big deal to be certain one way or another as we move forward to asnswer new questions and enhance our knowledge base as a species.

  • scribbler

    Much of today’s “science” is based upon FUNDING and not truth…

    Let’s say you just invested a coupla million dollars in a certain idea and someone comes out and blows the whole thing out of the water. You then have a vested interest in keeping those facts hidden…

    It is just as easy to have a pet theory with no proof whatsoever and some seeming verification comes along and you tout it as vindication and and then upon further review, the whole thing proves false. Again, a vested interest in keeping those facts hidden.

    So, if you want the truth, you must not only examine the so called facts that are presented but must examine the vested interest of those who present it…

    The first not terribly difficult. The latter, almost impossible to sift through…

  • John Stephens

    As soon as the original paper was published, Redfield went on the attack through her blog. This was well before any research was done to confirm or deny the paper’s claims. She then set about conducting experiments to disprove Wolfe-Simon’s results.

    This is not the way to conduct science. Redfield’s writings indicate she had a very strong prejudice from the start and I wouldn’t be surprised if it influenced the outcome of her experiments. “Science” is a good publication and I hope they took this in account when they reviewed Redfield’s paper. Still, until I read more information, I’m highly suspicious of it.

    I’m very interested in reading Wolfe-Simon’s critique of these papers. Redfield has for months been trying to point out flaws in Wolfe-Simon’s paper, now Wolfe-Simon finally has something that she can respond to. So far she has behaved like a true scientist. Redfield on the other hand has not.

    Normally I like Carl Zimmer’s writing, so I was surprised that he jumped on Redfield’s bandwagon so quickly. Personally I don’t care whether bacteria can use arsenic instead of phosphorus. It will be interesting if they can, and not surprising if they don’t. I think we’re going to have to wait for more studies by unprejudiced parties before we know for sure. This is tricky since we can’t directly observe what the bacteria are doing, so the experiments will probably have to be refined and conducted several different ways.

    Looking back through the history of science, just about all the discoveries that went against established dogma were immediately attacked like this, but eventually they were accepted after they were proven by good research. Perhaps that will be the case once again here. But we’ll have to wait. I doubt we’ll have a definitive answer for at least a year or two.

  • Pippa

    The whole point of science is that we question, question again and then attempt to disprove. That way we slowly move towards what is the most likely to be the truth. When early results are sensationalized by the media as a great new fact, then this type of retraction in public is bound to happen. Sadly, old and established findings are not news. I’d say the media is responsible for misleading the public, just as much as funding initially biases results. At least results are questioned, whereas we seem to carry on believing the half truths that we have seen published for a long time. Furthermore we believe that what we read is typical, we think that bias in science is more pervasive and misleading than it is, we are convinced that crime rates are high when they are falling, etc. Good education in the scientific method would help us to better understand what we read, but that seems to be less and less likely as time goes on. Ah well, I guess all civilizations eventually fall. I just hope the new dark ages don’t come along in my life time.


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