It's life Jim, but not as we know it...

NASA's astrobiology unit held a press conference yesterday, in which they made the eagerly-awaited announcement about their latest piece of research.

Now, given that an announcement from NASA's astrobiology unit was eagerly awaited, it's not surprising that there had been a lot of speculation that they'd discovered aliens. No serious commentators were expecting little green men, of course, but there was some quite serious speculation that they might have discovered some microbes, perhaps from an asteroid, of non-terrestrial origin.

Of course hyping the story in advance and putting an embargo on the details was a deeply silly thing to do (and led to this lovely little spoof). I won't say any more about that, because Ivan Oransky, the great expert of silly embargo stories, has already written about that aspect of the story far better than I could have done. But I would like to write something about what the researchers actually found, and the way this has been described in the mainstream media.

So, did they find aliens? Er, no. But what they did find is nonetheless pretty amazing stuff. The research is described in a paper in Science (disappointingly behind a paywall), and is a description of a bacterium, known to its friends as GFAJ-1, which inhabits an arsenic-rich lake, and can grow on arsenic instead of phosphorus.

What's so special about that? We knew that there were plenty of weird bacteria in extreme environments, didn't we?

Well, this one is different. What the researchers seem to have shown is that GFAJ-1 can incorporate arsenic into its DNA in place of phosphorus. If that's true (and this is the sort of story that is so amazing that it would be wise to see if other researchers can replicate the findings before getting too excited), then it is a stonkingly huge, mind-blowingly amazing, unbelievably staggering advance in our knowledge of basic biochemistry. If these findings are confirmed, then despite the absence of little green men, a Nobel prize for the scientists involved must be a shoe-in.

For those of you are aren't yet convinced about why this is, here's a little lesson in some basic biochemistry.

All living organisms known to science have a genetic code based on DNA, or, for a small number of viruses, RNA, which is very closely related to DNA. DNA consists of a series of nucleotides, which conventionally are denoted by the letters A, T, C, and G. The nucleotides are held together by phosphorus atoms, in long chains. DNA therefore consists of long chains of those A, T, C, and G letters. The sequence of letters is different in different organisms, but the basic structure of the DNA (or RNA, which is only a very minor variation on this), with nucleotides held together with phosphorus atoms, is the same for all organisms: human beings, chimpanzees, mice, oak trees, cabbages, mushrooms, bacteria, viruses, or even politicians. Exactly the same everywhere. This is how we know that all life on earth must have evolved from a single common ancestor.

However, GFAJ-1 appears to be different. If it's grown under conditions in which there is no phosphorus, but there is arsenic, it appears to be able not only to survive, which is pretty amazing, but also to construct its DNA by holding together its nucleotides with arsenic instead of phosphorus. That is the first time anyone has discovered any organism that has DNA that doesn't follow the standard template, and if confirmed, would, as I mentioned above, be a truly amazing discovery. It was previously regarded as a universal truth in biology that no organisms can survive unless supplied with the six elements carbon, hydrogen, oxygen, nitrogen, sulphur, and phosphorus. Now we know that there is at least one organism that can survive without phosphorus.

So, how did this get reported in the popular media?

The BBC broadcast news doesn't seem to even be aware of it. No mention of it at all on the main news bulletins on last night's BBC News at Ten, this morning's Today on Radio 4, or this morning's Breakfast on BBC 1. It can be found in the science pages of the BBC website, but is not obvious on the front page of BBC news without a lot of scrolling.

Even more disappointing than that, the article has a ridiculous headline: "Arsenic-loving bacteria may help in hunt for alien life". No, it doesn't help in hunt for alien life. This tells us absolutely nothing about alien life. It tells us some fantastically interesting things about life on planet earth, but nothing whatsoever about aliens. The rest of the article isn't that bad, but trying to present this as a lesson in alien life forms is just silly. Yes, we now know that a variation on DNA structure appears to be possible. However, if life does exist on other planets, did anyone seriously imagine that it would be based on DNA identical to ours?

The story also seems to be missing from the front pages of the major newspaper websites.

But of course, if we want to see a really silly story in the media, we can always rely on the good old Daily Mail. And on this occasion, they certainly don't disappoint. Not only does it have a silly headline, which also mentions aliens (although to be fair, we can't be too harsh on them for that when even the BBC talks about aliens in its headline), but the rest of the article continues the silly tone. The first sentence of the article is "NASA has discovered alien life – but it is right here on Earth." Oh dear. No, Daily Mail, it's not alien life. It's 100% terrestrial life, just with a really unusual biochemistry. We are also told "it markedly raises the odds of ET’s existence". Wrong again. Now they do say, in paragraph 17, that "it is not a true ‘alien’ with its own tree of life." Indeed it's not. So why did they call it an alien then?

Perhaps we should take comfort from the fact that they are correcting themselves a whole 2 paragraphs earlier than usual.

I don't know whether there is life on other planets. But I think we can be sure of one thing. If there is intelligent life on other planets, they probably don't read the Daily Mail.