Arsenic Aftermath

If you read the news, you’ll remember the Great Arsenic Bacteria Debacle of 2010.  In case you missed it, here is a brief summary. A NASA astrobiologist named Felisa Wolfe-Simon, along with some other researchers, published a paper in Science (second only to Nature as important academic journals go) in which they claimed to have discovered that a particular strain of bacteria was able to substitute arsenic for phosphorous in some of its biomolecules, including its DNA.

If this were true, it would be huge news. All living things use a few main elements (Carbon, Hydrogen, Nitrogen, Oxygen, Sulfur and Phosphorous) to produce lipids, amino acids and other important molecules.  There is some debate about whether these elements are therefore essential for life, or whether life might, in principle, use other elements instead. For example, some people think that alien life forms might be silicon-based rather than carbon-based.  So if it were true that this bacterium were substituting arsenic for phosphorous, it would be great news for astrobiologists because it would “expand the scope of the search for life for life beyond earth” (this from the NASA news report, which features a nice picture of the lake this bacterial strain lives in). And for those of us who don’t really care about aliens, the arsenic phenomenon would be a pretty incredible bit of biology in itself.

This got a lot of coverage in the media, especially considering it was only about science, rather than something interesting, like Charlie Sheen.  There was also a huge online response from the scientific community.  A scathing one.

Rosie Redfield, from UBC, led the charge with a blog post dismantling the original paper.  She pointed out a number of basic flaws in the research, concluding, “if this data was presented by a PhD student at their committee meeting, I’d send them back to the bench to do more cleanup and controls.” Oh, snap! Dozens of other scientists joined in the fray; the science writer Carl Zimmer covered the arsenic backlash here. The Science paper was thoroughly torn apart, and its claims about arsenic being incorporated into DNA ended up looking dubious. It was a glorious few days: the criticisms of the arsenic paper were far more entertaining than the original media coverage of the story had been, and you learned much more about science by reading them.

This was back in December.  Science (the journal) has just now published some official critiques of the original paper, which seem convincing.

I wonder, though: how many people will read those critiques, compared to the number that read the initial online critiques back in December?  Many of them are written by the same scientists, and cover the same points.  The main differences are that the criticisms are now granted extra legitimacy by being published in Science, and that they’re now five months behind.

Debate within the published literature moves at slower pace than online debate. Both are valuable, but the latter seems to be becoming increasingly important.  This seems like a good thing to me. For one thing, scientists write much better on blogs and in other informal contexts.  They communicate more clearly and come across as more human; sometimes they even use swear words. More importantly, people are much more likely to be interested in what scientists have to say if they (the scientists) can comment on a story like the arsenic bacteria one while it’s still relevant.

P.Z. Myers at Pharyngula has some interesting comments on why it’s unlikely that anyone will do any further research into the arsenic phenomenon (namely: because they won’t get funding and they won’t get published).


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