Arsenic life does not exist after all...

The claim that living things could use the usual molecules, just with arsenic switched for phosphorus in their DNA, was an extraordinary claim, and such a claim requires extraordinary evidence.<p><a href="http://skeptico.blogs.com/skeptico/2008/01/extraordinary-c.html" rel="nofollow">http://skeptico.blogs.com/skeptico/2008/01/extraordinary-c.h...</a><p>But the first report about "arsenic-based life" was no more than a preliminary research finding announced in a press event by the study sponsor, and such an announcement is not enough to establish a new body of scientific fact.<p><a href="http://norvig.com/experiment-design.html" rel="nofollow">http://norvig.com/experiment-design.html</a><p>The specific preliminary finding was criticized right away for sloppiness of technique and a rush to reach an unwarranted conclusion,<p><a href="http://scienceblogs.com/pharyngula/2010/12/its_not_an_arsenic-based_life.php" rel="nofollow">http://scienceblogs.com/pharyngula/2010/12/its_not_an_arseni...</a><p><a href="http://rrresearch.fieldofscience.com/2011/08/first-evidence-refuting-wolfe-simon-et.html" rel="nofollow">http://rrresearch.fieldofscience.com/2011/08/first-evidence-...</a><p>so the journal slated to publish the preliminary finding had to invite in critiques of the finding to save its own reputation.<p><a href="http://www.wired.com/wiredscience/2011/05/science-publishes-arsenic-is-life-responses-game-on/" rel="nofollow">http://www.wired.com/wiredscience/2011/05/science-publishes-...</a><p>Science is all about reproducible results, so much so that there is a humor magazine for scientists called the Journal of Irreproducible Results.<p><a href="http://www.jir.com/" rel="nofollow">http://www.jir.com/</a><p>The headline in New Scientist, a British popular magazine about science (something like Scientific American in the United States), which has been published since before I was born, is correct. There isn't any reliable evidence of arsenic-based life living anywhere within reach of scientists on earth. Not now, and not last year. The best summary of the current evidence, after the efforts of many more careful researchers, is "arsenic life does not exist after all," period (as an American would say), full stop (as a Briton might say).

I don’t think the scientific community really bought it in the first place. The original experiment wasn’t especially rigorous; e.g. see Rosie Redfield’s review <a href="http://rrresearch.fieldofscience.com/2010/12/arsenic-associated-bacteria-nasas.html" rel="nofollow">http://rrresearch.fieldofscience.com/2010/12/arsenic-associa...</a><p>And then the authors declined to respond in detail to any of the specific criticisms that had been made by other scientists, which is very rarely a good sign.

Serious biologists were very skeptical from the start : <a href="http://omicsomics.blogspot.com/2010/12/arsenic-and-new-microbes.html" rel="nofollow">http://omicsomics.blogspot.com/2010/12/arsenic-and-new-micro...</a><p>Soon, there were lots of questions : <a href="http://pipeline.corante.com/archives/2011/06/01/return_of_the_arsenic_bacterium.php" rel="nofollow">http://pipeline.corante.com/archives/2011/06/01/return_of_th...</a><p>I'm thinking NASA is good at space exploration, not so good at biology.

The title is a bit misleading. One other lab's failure to reproduce the results does not prove invalidity of the original publication. It certainly raises some eyebrows, but it makes sense to wait and see what comes of Wolfe-Simon's further analysis before we declare that arsenic life definitely does not exist.

Even if the organisms were shown to swap out phosphorus for arsenic in some instances in their DNA, would that be surprising? Arsenic comes from the same column in the periodic table as phosphorus, and exhibits many of the same macro chemical properties as phosphorus.<p>It would be like a software engineer swapping out their optimized, say, C++ string library, for one that was less optimal but perhaps took less space or ran better in a constrained embedded environment. Arsenic might not be optimal but it's what's available, what can be used.<p>In the software case you'd probably be OK but run more slowly than otherwise, or else maybe you'd stumble when for some strange reason the sub-optimal string library didn't guarantee thread-safe read operations. The arsenic could similarly trip up the organism in some cases.

I've never heard of new scientist. Is it a real science journal or sensationalist? (based on this article I'd guess the latter)

Summary: Scientist B failed to replicate the results of Scientist A. Scientist A stands by her continuing research. Research continues and is not definitive yet. New Scientist has a slow news days and publishes said results, mucking up an extra controversy for the day and getting a few more clicks through to their website.