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JISHOU, HUNAN — Just a few days ago, the Internet was in a hub-bub about the discovery of a strain of bacteria that thrives in an arsenic-laced environment.

Several biologists, however, are not so convinced, and have pointed out weaknesses in the scientific paper announcing the discovery. Carl Zimmer at Discover magazine just published a summary of some of these objections.

The late astronomer and author Carl Sagan once wrote that “extraordinary claims require extraordinary evidence.” In other words, if you claim you saw a UFO zipping across the sky from your backyard, your photographic “proof” had better not look like blurry shot of a modified dinner plate. Briefly, that’s what critics of the arsenic-loving bacteria paper are saying. They believe the authors’ methodology and analysis is flawed, so they want further evidence that these bacteria have really incorporated arsenic into their DNA, for example.

This is how science works. Even Newton and Einstein, whose theories of gravity and relativity are now considered foundations of modern physics, had their critics when they were first published. Science is all about testing and verification of hypotheses. Peer-reviewed journals, like Science, run submissions past a panel of editors, who judge in part whether the authors of the paper did an acceptable job of supporting their conclusions. Then, once it’s published, scientists reading the paper get to pick it over, too, as they are doing now with the “arsenic aliens.”

Valid criticisms require the authors to re-check their methodology, analysis and conclusions. Perhaps other researchers will attempt the same kind of investigation, to see if they get the same results. For an experiment or analysis to be considered scientifically valid, it has to be repeatable, after all.

If, after all this checking and re-checking, the original conclusions still hold water, then scientists will accept them as tentatively valid, meaning it may take years, even decades, before those findings end up being part of the scientific “furniture.”

Unfortunately, the popular media don’t convey this process well at all. It’s a lot more fascinated to read “scientists discover brand-new lifeform” than “maybe some bacteria can use arsenic to live, we think. Let us get back to you on that.”