Last night, in a spectacular display of superhuman ignorance, Richard Hoagland managed to ask the wrongest possible question about arsenic substitution in biochemistry, and then capped it by coming up with the most ridiculous possible answer. He wondered aloud to his radio audience of millions why none of the journalists at the afternoon's NASA press conference had asked whether the extremophile bacterium GFAJ-1 came from an extraterrestrial source, and declared that to him the answer was obvious — yes, of course it did. "There is an alien in our midst," he said theatrically.
To recap, for those who did not follow the day's events, the NASA astrobiology program called the conference to announce a very unusual finding. Geomicrobiologist (and, it turns out, accomplished oboist) Felisa Wolfe-Simon, a rather fetching tousle-haired nerd's dream-girl, took the credit for the discovery that, in conditions of restricted environmental phosphorous, GFAJ-1 can use arsenic instead, in building the DNA backbone upon which it depends to function. Wolfe-Simon had theorized that this might be possible, and had gone to Mono Lake in a successful search for proof.
It was a pretty brilliant piece of work by Dr Wolfe-Simon, and it took an intellect as puny as that of Richard C. Hoagland to misunderstand it quite that thoroughly.
Mono Lake, a couple of hundred miles East of San Francisco, is a natural chemistry experiment gone awry. Indifferent water management over the centuries has made it highly saline and unusually alkaline, and mine tailings from the California gold rush have bequeathed it near-toxic levels of arsenic. Yet gamma-proteobacteria like GFAJ-1 have found a way to make a living there.
It's one of the best-established principles of evolution that organisms adapt to their environment. If the environment places stress on a population — say by getting hotter, drier, or more acidic — the population is selected for those individuals that tolerate the stress best. Over time, the population either fails to adapt and dies out, or develops a new strain that finds the environment congenial. Well, lo and behold, as Lake Mono became deficient in phosphorous and oversupplied with arsenic, the plucky little bacterium found a way of making do. High arsenic = arsenic-tolerant bacteria. Simple, really. So for Richard Hoagland, with no knowledge of biochemistry whatsoever, to ask which distant galaxy might have seeded the lake with GFAJ-1 is like him finding an apple on the ground under an apple tree and saying "Hmmm, wonder where that came from?"
The DNA molecule has been likened to two intertwined spiral staircases — and the metaphor works well up to a point. The four-letter code of A,T,C,G is contained on the stair steps. Where one step is an A, its matching step on the other spiral must be a T. Where one is a C, the other must be a G. However, an actual double stairway would have a central pillar to support the whole structure — and there the metaphor fails because there's no molecular equivalent. Instead the supporting "backbone" of DNA is on the outside — looking more like the handrails of the stairs. And it's here that phosphorous, alternating with what are essentially sugars, plays its essential role. In short, the substitution of arsenic for phosphorous is just a cleverly improvised feat of molecular carpentry and would not signify extraterrestrial origin to anyone with any knowledge of biochemistry.
I did sort-of follow his next proposition — namely, that the still-upcoming STS-133 space shuttle mission is the first "post-Newtonian" mission. This means, according to Hoaglandian logic, that the energy needed to get the shuttle to orbit will come, not from old-fashioned rocket fuel, but from "hyperdimensional space, torsion physics, and etc. etc. etc." I'm sure this comes as a surprise to everybody involved in the mission.
A classic Hoaglandian performance, ending with — guess what? — an 800 number that will put cash in the Hoagland pocket.
Way to go, Coast.
Two criticisms of the experiment from biochemists have now surfaced in the blogosphere. Both seem quite harsh.
Although it might be entertaining to watch the biochemists slug it out in blogs, you can bet that isn't going to happen. It's just not dignified for the lead author of a paper in a peer-reviewed journal to respond to informal critiques.
Well, surprise—there is now a response from Dr Wolfe-Simon, although not in a blog or a tweet.
STS-133 went from ground to orbit powered by LH2/LO2, just as normal.