Tag Archives: arsenic

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The perils of science hyperbole

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The fallout from the NASA paper on arsenic-eating critters has taught us a lot more about the life-cycle of exciting science stories than it has about the life-cycle of the critters themselves. Molecular biologist and super-sharp sf commentator Athena Andreadis does a post-mortem:

This is not the first or only time NASA administrators have been callously cavalier.  Yet even though the latest debacle didn’t claim lives like the Challenger incident did, it was just as damaging in every other way.  And whereas the Challenger disaster was partly instigated by pressure from the White House (Reagan needed an exclamation point for his State of the Union address), this time the hole in NASA’s credibility is entirely self-inflicted.  Something went wrong in the process, and all the gatekeeping functions failed disastrously.

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NASA spokespeople, as well as Wolfe-Simon and Oremland, have stated that the only legitimate and acceptable critiques are those that will appear in peer-reviewed venues – and that others are welcome to do experiments to confirm or disprove their findings.

The former statement is remarkably arrogant and hypocritical, given the NASA publicity hyperdrive around the paper: embargoes, synchronized watches, melodramatic hints of “new life”, of a discovery with “major impact on astrobiology and the search for extraterrestrial life”.  This is called leading with your chin.  And if you live by PR, you cannot act shocked and dismayed when you die by PR.

As for duplicating the group’s experiments, the burden of proof lies with the original researchers. This burden increases if their claims are extraordinary.  The team that published the paper was being paid to do the work by a grant (or, possibly, by earmarked NASA money, which implies much less competition). For anyone else to confirm or disprove their findings, they will have to carve effort, time and money out of already committed funds — or apply for a grant specifically geared to this, and wait for at least a year (usually more) for the money to be awarded.  It’s essentially having to clean up someone else’s mess on your own time and dime.

Hyperbolic science PR is nothing new, of course, but it’s damaging and counter-productive in these politically-charged times:

By disbursing hype, NASA administrators handed ready-made ammunition to the already strong and growing anti-intellectual, anti-scientific groups in US society: to creationists and proponents of (un)intelligent design; to climate change denialists and young-earth biblical fundamentalists; to politicians who have been slashing everything “non-essential” (except, of course, war spending and capital gains income).  It jeopardized the still-struggling discipline of astrobiology.  And it jeopardized the future of a young scientist who is at least enthusiastic about her research even if her critical thinking needs a booster shot – or a more rigorous mentor.

There’s some sort of deep sad irony in here: our hunger for exciting new truths can jeopardise our chances of discovering them.

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The arsenic aliens that aren’t

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Typical, really; the day I’m away from my desk, a big sf-flavoured story hits the blogosphere. I speak, of course, of NASA’s press conference about the discovery of “alien” life… not at the top of the gravity well, but at the bottom of an arsenic-laced lake in Yosemite National Park. From Wired UK (whose new page layouts are much easier on the eye, but disappointingly similar to their US counterparts):

The bacteria, found in the bed of Mono Lake, are believed to exist as a second form of life — using arsenic in cells in place of the phosphorous found in most living cells.

That suggests that they’ve developed entirely independently from our life, implying that if life has evolved twice on Earth, then it’s far more likely to have evolved off Earth too — especially as it’s believed by astronomers that among stars similar to the Sun, as many as one in four could have small rocky planets like Earth, at least some of which would occupy the same “goldilocks zone” that Earth exists in — neither too hot, nor too cold, for life to emerge.

Leaving aside the actual story for a moment, the meta-story – namely how excited the public can get about the possible announcement of alien life – is worth considering as well. I’ve got no criticism for NASA over the way they framed their announcement; it’s no more duplicitous than the PR operations of the average corporation or government, and I know which I’d rather be paying attention to. But as New Scientist points out, the possibility of actual evidence for extraterrestrial life – which is what a lot of people thought (or hoped) was on the cards – was embraced with a cheery enthusiasm by all sorts of news outlets. Perhaps the world’s gotten so weird lately that nothing can surprise us any more… or perhaps we’re still secretly hoping that sentient ET(s) will turn up, Intervention-style, and pull our collective homo sapiens backsides out of the frying pan we’ve been cheerfully heating up for ourselves. (The writer – and reader! – in me would still quite like the latter to happen, not because I think we actually deserve a species-level bailout, but because the frying pan would doubtless be succeeded by a very interesting succession of fires.)

Anyway, the important thing about the arsenic-alien-life story is that it’s not quite as big a deal as the headlines would have it. It’s still pretty fascinating stuff that connects to extremophile life, but – as explained by Paul Gilster at Centauri Dreams – it’s not evidence for “shadow biospheres”, and doesn’t really tell us anything about extraterrestrial life that we haven’t already hypothesised.

Let’s leave the astrobiology aside for the moment and simply focus on the fact that life is fantastically adaptable in terms of biochemistry, and can pull off surprises at every turn. That’s always a result worth trumpeting, even if it leaves the wilder press speculations in the dust. After all, it’s long been assumed that the six elements that underlay the basic chemistry of life are carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur. Despite persistent speculation, few thought life could exist without them.

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Can these bacteria replace phosphate with arsenic naturally? Wolfe-Simon herself says thirty years of work remain to figure out exactly what’s going on, a comment on the preliminary nature of this work, which remains controversial in some quarters and is in obvious need of extensive follow-up. No shadow biosphere yet, but obviously the quest is ongoing because of its implications, and we’ve now received one very tantalizing piece of evidence that such things may be possible.

If life really did start here more than once — a finding that is not remotely demonstrated by this work — then we can talk about how likely it will have done the same thing on distant planets, upping the chances that we live in a universe where life emerges whenever given the chance.

And here’s PZ Myers, taking a break from being Dawkins’ bulldog to dig into the actual science of the paper:

You’d predict just from looking at the [periodic] table that arsenic ought to have some chemical similarities to phosphorus, and you’d be right. Arsenic can substitute for phosphorus in many chemical reactions.

This is, in fact, one of the reasons arsenic is toxic. It’s similar, but not identical, to phosphorus, and can take its place in chemical reactions fundamental to life, for instance in the glycolytic pathway of basic metabolism. That it’s not identical, though, means that it actually gums up the process and brings it to a halt, blocking respiration and killing the cell by starving it of ATP.

Got it? Arsenic already participates in earthly chemistry, badly. It’s just off enough from phosphorus to bollix up the biology, so it’s generally bad for us to have it around.

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So what does it all mean? It means that researchers have found that some earthly bacteria that live in literally poisonous environments are adapted to find the presence of arsenic dramatically less lethal, and that they can even incorporate arsenic into their routine, familiar chemistry.

It doesn’t say a lot about evolutionary history, I’m afraid. These are derived forms of bacteria that are adapting to artificially stringent environmental conditions, and they were found in a geologically young lake — so no, this is not the bacterium primeval. This lake also happens to be on Earth, not Saturn, although maybe being in California gives them extra weirdness points, so I don’t know that it can even say much about extraterrestrial life. It does say that life can survive in a surprisingly broad range of conditions, but we already knew that.

I can’t help but feel a twinge of disappointment myself, really; cynical I may be (YA RLY) but I’d still love to hear we’d found solid evidence of truly alien life. But you know what? News that the life we already know works in weirder and more tenacious ways than we previously thought is enough to give me a sensawunda kick. I suspect that if you’re not continually astonished by nature’s diversity, you probably don’t yet know enough about it*.

[ * Yeah, I’ve been binging on documentaries from the BBC’s iPlayer service on these chilly evenings; so sue me. I might as well enjoy bachelordom to the full, no? 😉 ]