The arsenic aliens that aren’t

Paul Raven @ 03-12-2010

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.


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.


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? 😉 ]

The Galactic Area Network

Paul Raven @ 29-06-2010

The wonderfully named John Learned of the University of Hawaii theorises that alien intelligences could use Cepheid variable stars as nodes on a sort of intragalactic communications network [via @spacearcheology, who retweeted @swadeshine]:

Jolting the star with a kick of energy – possibly by shooting it with a beam of high-energy particles called neutrinos – could advance the pulsation by causing its core to heat up and expand, they say.

That could shorten its brightness cycle – just as an electric stimulus to a human heart at the right time can advance a heartbeat. The normal and shortened cycles could be used to encode binary “0”s and “1”s.

The team says information could thus be shuttled around our galaxy’s network of 500 or so Cepheids – and out as far as the Virgo cluster of galaxies.

Because a civilisation capable of such engineering feats would be sure to turn them to the task of… er, using stars as Morse keys. This guy has made exactly the mistake that Sam Vaknin was on about.

Predator versus alien: this will surely not end well

Paul Raven @ 10-03-2010

Japanese knotweedWhile Alabama may have its congongrass, we here in the UK have our own invasive species of Far Eastern weed in the form of Fallopia japonica, better known as Japanese knotweed. In their great wisdom, our Department for Environment, Food and Rural Affairs is planning to introduce another alien species – a form of plant lice – into the ecosystem to get rid of it. [image by dankogreen]

Laboratory tests were started on pests from Japan which control the knotweed by feeding on sap from its stems, causing the plant to die back.

The tests showed the chosen Aphalara itadori did not eat any other species, including closely related British plants and important crops.

Genius! I mean, the odds of a short-lifespanned insect evolving itself a wider diet when introduced to a totally new biosphere must be so small as to be negligible. Nothing could possibly go wrong with this plan!

Paging John Wyndham… would John Wyndham please report to the briefing rooms…

Are we alone?

Tom James @ 10-07-2009

saucersTranshumanist blogger George Dvorsky points to a debate between astrophysicist Brandon Carter and a team of Serbian researchers, the core of which revolves around how long complex (and intelligent) life takes to evolve:

Prior to ‘recent times’, universal mechanisms were in place to continually thwart the evolutionary development of intelligence, namely through gamma-ray bursts, super novae and other forms of nastiness. Occasional catastrophic events have been resetting the “astrobiological clock” of regions of the Galaxy causing biospheres to start over. “Earth may be rare in time, not in space,” they say. They also note that the rate of evolution is intimately connected with a planet’s environment, such as the kind of radiation its star emits.

For further discussion of our place in the universe see the Copernican Principle, which exhorts us to avoid assuming that humanity, Earth, and our place in the universe can be assumed to be unique and special.

Further the notion of punctuated equilibrium to describe evolution is interesting: might it be extended to describe other evolutionary phenomena? Eric Beinhocker‘s superb The Origin of Wealth describes both technology and the economy in terms of evolutionary systems, both of which experience a form of punctuated equilibrium.

[image from eek the cat on flickr]

Does the Earth harbour a ‘shadow biosphere’?

Paul Raven @ 17-02-2009

alien desertDoes the Earth harbour forms of life unrelated to the carbon-based DNA-powered stuff we know about? “Impossible,” you might say, but as pointed out by astrophysicist Paul Davies, we wouldn’t know – because we’ve never looked for it.

“Our search for life [has been] based on our assumptions of life as we know it. Weird life and normal life could be intermingled, and filtering out the things we understand about life as we know it from the things we don’t understand is tricky.”

The tools and experiments researchers use to look for new forms of life – such as those on missions to Mars – would not detect biochemistries different from our own, making it easy for scientists to miss alien life, even if was under their noses.

Alternative biochemistry is inherently a speculative field, which is why it has made plenty of appearances in science fiction – Rudy Rucker has dealt with similar ideas before, for example, and Futurismic columnist Mac Tonnies has theorised about the potential of Earth being home to beings we are not able to recognise as such.

Finding examples of alien life here on Earth might add credence to theories like panspermia – but, more importantly, it would suggest that the likelihood of life developing elsewhere in the universe is closer to one than to zero. [via SlashDot; image by Haeroldus Laudeus]

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