Scientists: NASA’s alleged discovery of arsenic-based life is crap

I gave it the front-page treatment when the big announcement was made, so now the big skeptical response gets front-page treatment too. Simply devastating — so much so that I wonder why it fell to an outfit like Slate to put it together. Did the Times or WaPo not have enough of an inkling about NASA’s discovery to survey naysayers before writing up their reports on the “discovery”? This information would have come in a lot handier when everyone was still paying attention to this story.

As soon Redfield started to read the paper, she was shocked. “I was outraged at how bad the science was,” she told me.

Redfield blogged a scathing attack on Saturday. Over the weekend, a few other scientists took to the Internet as well. Was this merely a case of a few isolated cranks? To find out, I reached out to a dozen experts on Monday. Almost unanimously, they think the NASA scientists have failed to make their case. “It would be really cool if such a bug existed,” said San Diego State University’s Forest Rohwer, a microbiologist who looks for new species of bacteria and viruses in coral reefs. But, he added, “none of the arguments are very convincing on their own.” That was about as positive as the critics could get. “This paper should not have been published,” said Shelley Copley of the University of Colorado…

In fact, says Harvard microbiologist Alex Bradley, the NASA scientists unknowingly demonstrated the flaws in their own experiment. They immersed the DNA in water as they analyzed it, he points out. Arsenic compounds fall apart quickly in water, so if it really was in the microbe’s genes, it should have broken into fragments, Bradley wrote Sunday in a guest post on the blog We, Beasties. But the DNA remained in large chunks—presumably because it was made of durable phosphate. Bradley got his Ph.D. under MIT professor Roger Summons, a professor at MIT who co-authored the 2007 weird-life report. Summons backs his former student’s critique.

But how could the bacteria be using phosphate when they weren’t getting any in the lab? That was the point of the experiment, after all. It turns out the NASA scientists were feeding the bacteria salts which they freely admit were contaminated with a tiny amount of phosphate. It’s possible, the critics argue, that the bacteria eked out a living on that scarce supply. As Bradley notes, the Sargasso Sea supports plenty of microbes while containing 300 times less phosphate than was present in the lab cultures.

The authors of the study declined to address the criticisms when contacted by Slate, but even a dummy like me wondered whether the bacteria might simply have been surviving like camels on tiny amounts of phosphorus instead of incorporating arsenic into its DNA. The theory proposed by at least one skeptic, in fact, is that the arsenic isn’t being incorporated at all; it’s simply adhering to the phosphorus that forms the framework of the DNA double-helix like gum on the bottom of a shoe.

Follow the link and read the whole thing. It’s essential if you tracked the story last week when it first broke. Exit question one via Greg Pollowitz: Did NASA have any financial motive in hyping this discovery? Exit question two: Should the GOP hold hearings if the study falls apart? C’mon — C-SPAN testimony on freaky deaky microbes would be riveting television.

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