On December 2, 2010, Science published a surprising research article entitled “A bacterium that can grow on arsenic instead of phosphorous,” written by Felisa Wolfe-Simon and her colleagues from NASA and the US Geological Survey. Since at least 1919, biochemists have known of phosphorus’s role in DNA, and since then it has proven to be a crucial atom in genetics, metabolism, and regulation. All observed life forms contain carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus… until this paper. Wolfe-Simon reported the discovery of a bacterium which, among other achievements, incorporates arsenic into its genetic code rather than the usual phosphorus. For perspective on this scientific bombshell, one blogger compared the incredible discovery to “cold fusion with DNA.”
To refute one of the basic tenets of Earthly biology — that life requires phosphorus — requires extraordinary evidence, which the academic community largely felt was not provided in the original article. Upon publication, the paper was immediately assailed by field experts in a flurry of letters to the editor, comments, blogs, and even tweets. In one of the kindest responses to the publication, origins-of-life expert Steve Benner wrote:
“Their hypothesis that this microorganism contains DNA and other standard biomolecules in which arsenate atoms replace phosphorus atoms would, if true, set aside nearly a century of chemical data concerning arsenate and phosphate molecules, revolutionize our view of bacterial metabolism, and radically alter our understanding of microbial adaptation. This does not mean, of course, that the hypothesis should be discarded out of hand. Automatically discarding results inconsistent with decades of work, if generally applied, would cause us to overlook most valid advances in science.”
I wholly agree with this sentiment. But the nucleic acid chemist then went on to estimate that the half-life of arseno-DNA in water is about a minute, whereas the half-life of DNA in water is in the neighborhood of 30 million years. This is just one of many reasons that additional experiments are required. (For additional technical critiques from the community, see comments on the article’s webpage here and biologist Rosie Redfield’s blog post and its comments.
This month, reports published in Scinece (here and here) formally refute Wolfe-Simon’s claim. This two year row brings to light a number of issues in science sensationalism, which I hope will not be forgotten in the aftermath.
The good. In general, I love when the news cycle grabs a science story. It means that the newsworthy atrocities ordinarily happening across the globe are at a temporary lull. It also means that a scientist has captured the imagination, curiosity, and awe of the public. Taxpayers, just for a moment, might appreciate the money they have spent on research (wishful thinking, I know). And if we’re really lucky, the story might just seed scientific curiosity in a child. Win!
The bad. Unfortunately the good of this particular news story ends there. If the title of the original publication did not pack enough punch, headlines in the popular press typically read “Are aliens among us? Sort of, NASA says.” This is certainly a loose translation of the technical work, and I would have vastly preferred to see something along the lines of “Scientists disprove Biology 101” But what else could one expect? The article came from a top US institution and a top journal. It was rushed to publication and printed with a title which implied unequivocal truth. Criticism was (and is still being) handled unbelievably poorly by the authors, who have been forced to stick to shaky evidence by an unexpected media onslaught. As usual, the information that trickles from the bench to the breakfast table has been wildly distorted. The public deserves better.
The ugly. To me, this story is all about the sacrifice of good science for some time in the spotlight. Broadly speaking, NASA (and particularly its astrobiology division) was in need of some positive press. The journal Science was in need of page hits and subscriptions. The author, at the start of her career, was in need of a better impact factor. In an interview, Wolfe-Simon stated:
“We could have waited until we did a really exhaustive selection of all of these alternative techniques, many requiring collaborations with groups well outside of our field, but, instead, I and my co-authors, we wanted to provide a strongly suggestive and convincing argument to our community to initiate these new collaborations and really inspire other people to go out and do this totally in de novo.”
Personally, I find this approach to science inexcusable. The authors’ interesting hypothesis that life could be supported by alternate elements is an intriguing one. But prior to publication, the proper verification of a hypothesis requires experiments that attempt to both prove it and to disprove it; only by disproving all other explanations can a hypothesis be accepted. In this case, it appears that the authors intended to provoke the community with weakly positive evidence and a flashy title, rather than do their best to find the truth.
As for the journal Science – the occasional publication of incorrect interpretations is inevitable. That’s what the cutting edge of research is all about. However, the journal should examine its review process; if its reviewers represent expert opinion in their field, it should have been difficult for the journal to find anyone in support of publication. As a budding scientist, note to self: Don’t bother with the details, just concoct a great story.
But, with all these disappointments comes one great comfort. Although the review process failed and science journalism has seen better days, science did not fail. Two years after the original publication, we know the truth — that arsenic atoms stick to DNA like gum on a shoe. We have a very interesting organism that is able to scavenge phosphorus in a sea of arsenic, a very similar atom. Science prevailed in the end!
— Laura E. Timmerman