


The state of the universe.
May 27 2011 4:50 PM

The Discovery of Arsenic-Based Twitter

How #arseniclife changed science.


Cast your mind back six months, to late November 2010. Wikileaks had unveiled the first goodies from its cache of 250,000 State Department cable. Hosni Mubarak's National Democratic Party was coasting toward yet another easy win in Egyptian elections. And, for just a few days, a lot of us wondered if NASA had discovered aliens.

If you've forgotten about that otherworldly dalliance, today is a good time to refresh your memory. On Nov. 29, NASA announced that it would soon hold a press conference to "discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life." Wild speculation ran amok—perhaps scientists had found living things on one of Saturn's moons. At the press conference, the scientists did not unveil an actual extraterrestrial, but they did have big news. A new paper had just been published in the journal Science, they said, which described bacteria that seemed able to build their own DNA from arsenic. If that were true, it would be an historic discovery, because no such ability has ever been found among Earth's life-forms.


Technically speaking, though, Science didn't so much publish the paper last fall as post a web-only version on a page called Science Express. Month after month went by, and it didn't appear in the actual paper-and-ink journal. Rumors circulated that a number of scientists had sent in formal criticisms (known in the business as "technical comments"), arguing that the study hadn't come close to demonstrating that the bacteria were growing on arsenic. But these never appeared in print or online. Finally, this morning, Science posted eight critiques of the paper to the website, along with an extended response from the original authors. The June 3 print edition of the journal will include both the paper itself and the follow-up discussion. For scientists who only get their information in print, this may be the first they've heard anything about a longstanding controversy that's come to be known over the past six months by its Twitter hashtag: #arseniclife.


NASA, Science, and the arsenic-researching scientists kicked off the whole affair by doing what scientists and scientific institutions always do. They were excited that they had made a game-changing discovery, so they submitted a paper to one of the world's top scientific journals. The paper went through peer review, and then reporters were given copies of the paper in exchange for agreeing to an embargo. NASA scheduled their attention-grabbing press conference to begin at 2 p.m. on Dec. 2, the very minute that Science lifted its embargo.

Everything seemed to be going according to plan—until NASA posted a terse, mind-bending announcement of a press conference about extraterrestrials. I suppose NASA imagined that the announcement would be noticed only by science writers who knew the drill, and understood what the press conference would be about. If that's true, they exhibited some woefully 20th-century thinking. Bloggers quickly picked up on the announcement, and the possibility that we'd discovered E.T zipped through the media ecosystem, eventually ending up on the websites of major news organizations.

The longer that people speculated, the more absurd the embargo policy became. Science and NASA could have put a stop to all the misinformation and hype with the simple click of a "publish" button. Instead, Science and NASA continued with their ritualized silence. Only at the press conference did they set matters straight: No, they hadn't found life on one of Saturn's moons. Instead, they had found what seemed to be a remarkable microbe in Mono Lake, California. If microbes could live on arsenic here on Earth, they argued, then we should expand the range of planets on which we search for life.

The paper received massive press coverage around the world. The first wave of articles only offered a faint hint that some scientists were suspicious. It turned out there was actually a deep vein of skepticism. Many scientists believed that the #arseniclife team were leaping to conclusions. Their experiments weren't rigorous enough to rule out more prosaic explanations for the data—for example, that the bacteria were actually tucking away arsenic in pouches, rather than using it to build their DNA.

In earlier times, such critics didn't have many options. They could write to Science and hope that their letter would be published long after the public's attention had turned to other things. They could write to their local newspaper and try to sum up their objections in 50 words. They could grouse over a beer with likeminded colleagues. Now, however, they can form an online community. Blogging scientists read the #arseniclife paper and aired their complaints. On Twitter, they kept each other up to date on new developments in the story. Within a couple weeks the New York Times and the Washington Post were reporting not on the Science paper, but on the online debate. The center of gravity had shifted.