Then it was an earth bacteria that has a unique kind of arsenic-based DNA – an entirely new kind of organism.
Then it merely could use arsenic in its DNA, if forced to, although under normal conditions it didn’t.
But now, it’s looking like it’s just a regular (albeit tough) bug – and a lot of hot air.
The “arsenic-based alien bacteria” story attracted more media attention than any other scientific paper of the last year. At first, I was very pleased by this: to a scientist, the discovery of an organism that can use arsenic instead of phosphorous in its DNA would have been massive news, with big implications for every branch of biology. How great that the media picked up on the importance of this story, even though it’s about a specialized point of biochemistry, I thought.
Unfortunately, as you’ve probably heard, serious questions have been asked about the Science paper announcing the findings. For details, see microbiologist Rosie Redfield’s devastating post on the topic: Arsenic-associated bacteria (NASA’s claims), and this one from Alex Bradley: Arsenate-based DNA: a big idea with big holes. In a nutshell, the critics make a very strong case that the evidence supposedly showing arsenic-containing DNA is flawed, and fairly obviously so.
As I’ve said before, this kind of thing is why science blogging is so important. Thanks to bloggers such as those I’ve linked to, and many others, this paper – which has enormous implications, if true – has been subject to detailed scrutiny within days of publication.
Without blogs, these questions would certainly have been asked sooner or later – but with the emphasis on “later”. The traditional way to criticize a paper is to write a Letter to the Editor of the journal that published it but this usually takes, at best, weeks, and usually months to appear.
Some journals now feature “e-letters” which can appear within hours, or public comment threads attached to each paper, and this is certainly a big step forward. Blogs still have the edge, though, because it’s often hard to incorporate pictures, html, etc. into these comments, and these discussion threads often become very hard to read as the important comments get mixed up with less useful, or simply out of date, ones.
A blog post, clearly setting out the arguments, and updated as new information comes to light, is, to my mind, the best form of scientific peer review we currently have.