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? 😉 ]


Reasons not to commercialise space

Paul Raven @ 18-11-2010

1) Marx wouldn’t approve! And anyway, we can learn about our relationship to the wider cosmos just as effectively from the surface of the Earth:

So outer space technology can be used for tackling a number of immediate social and political issues. But these strategies do not add up to a philosophy toward outer space and the form humanization should take. Here again, the focus should be on the development of humanity as a whole, rather than sectional interests. First, outer space, its exploration and colonization, should be in the service of some general public good. Toward this end, the original intentions of the 1967 UN Outer Space Treaty should be restored. Outer space should not be owned or controlled by any economic, social, and political vested interest. The cosmos should not, in other words, be treated as an extension of the global environment, one to be owned and exploited. We have seen enough of this attitude and its outcomes to know what the result would be. Spreading private ownership to outer space would only reproduce social and environmental crises on a cosmic scale.

I’d agree that space shouldn’t be owned or controlled by vested interests, but I rather suspect that it won’t be very amenable to such any control, by dint of its, well, space; territorial disputes are a function of limited room for expansion, and it’ll take us a long while to run out of lebensraum at the top of the gravity well. Why fight for territory when it’s less effort to strike out for an unclaimed patch? Indeed, I suspect conflicts in space are more likely to retain the ideological character of those currently popular on Earth’s surface… viz. Ken MacLeod’s Fall Revolution series, Sterling’s Schismatrix. Is that a reason to avoid going there? I’m not so sure; I don’t think we’re any more likely to solve those problems by simply staying put.

Frankly, I’m right behind George Dvorsky on this one, who says “… I couldn’t help but think that Marxist analyses are growing increasingly irrelevant and anachronistic […] Economic determinism ain’t what it used to be.” Marxism is a useful critical framework when used alongside others (especially in literature), but on its own it seems hopelessly idealistic, ignorant of (or uncaring for) post-modern networked global culture, and soundly lodged in the craw of Victorian industrialisation. Cue brickbats from my more radical left-wing readers… but the world has changed a lot since Marx, while Marxism hasn’t changed at all. YMMV. 🙂

2) We can’t survive out there! We’re designed to be planet-dwellers!

What is of greatest concern here is that, unlike muscle loss which levels off with time, bone loss seems to continue at a steady rate of 1 to 2 per cent for every month of weightlessness. During a three-year mission to Mars, space travellers could lose around 50 per cent of their bone material, which would make it extremely difficult to return to Earth and its gravitational forces. Bone loss during space travel certainly brings home the maxim “use it or lose it”.

[…]

The impossibility of an escape to space is just one of many examples of how our bodies, and those of our fellow organisms, are inseparable from the environments in which we live. In our futuristic ambitions we should not forget that our minds and bodies are connected to Earth as by an umbilical cord.

Well, yes, but umbilical cords can be cut and tied off; indeed, to extend the metaphor, cutting the cord is an essential step toward independence from one’s mother. And if our bodies are inseparable from our environments, we can hack one or both of them; if Human1.0 with default settings can’t live in space, we can upgrade her and her environmental surroundings. The biological status quo is not a cage, it’s a room with a door whose lock requires dexterous but doable picking.

There are concepts in development for spacecraft with artificial gravity, but nobody even knows what gravitational force is needed to avoid the problems.

Oh, I’d have guessed something approaching 10m/s² would do it… call it intuition. Anyway, Karl Schroeder’s done a better job than I can of deflating the long-standing “it’s too dangerous!” hand-wringing about space travel; of course there are challenges, but they’re far from insurmountable. Where there’s a will, and all that.

And as a wee bonus, here’s a new twist on an old fandom favourite:

So far, boneless creatures such as jellyfish are much more likely than people to be able to return safely to Earth after multi-year space trips.

Intelligent jellyfish in spaaaaaaaace… why should squid get all the glory, eh? 🙂


Genesis reloaded: are there forms of life on Earth we’ve missed?

Paul Raven @ 11-11-2010

It’s a well-used riff, but it seems to be making a comeback in recent months: is there a “shadow biosphere” of lifeforms on Earth that don’t obey the known rules of biochemistry? And if so, how might we find it – let alone recognise it when if do? A nice long article; you should go read the whole thing, but here’s a few snippets:

To investigate a species of microbe fully, you first need to culture it in the laboratory and then study its biochemistry by sequencing its genome to position it on the tree of life. This technique, while undoubtedly important, has its problems.

Many microbes don’t like being plucked out of their natural habitat and cannot be cultured easily. Some resist gene sequencing.

And, because the chemical techniques used to analyse microbes are customised and targeted to life as we know it, they wouldn’t work on an alternative form of biology. Should there be a different type of microbial life out there, it is very likely to be overlooked, simply because it would be unresponsive to the biochemists’ probes used so far. In a laboratory sample it might well get thrown out with the garbage.

If you set out to study life as we know it, then what you find will inevitably be life as we know it. It’s therefore an open question whether some microbes might actually be the descendants of a different genesis.

[…]

Notwithstanding their exotic nature, to date all extremophiles that have been analysed are standard life: they belong to the same tree of life as you and me. Their existence proves that the range of conditions under which standard life can survive is much broader than previously suspected. Nevertheless there are limits.

If there is a shadow biosphere, it might be occupied by weird ‘hyper-extremophiles’ inhabiting environments beyond the reach of even the hardiest form of standard life, and have so far escaped detection because nobody thought to look for any form of life under such extreme conditions. A good example is temperature: standard hyperthermophiles seem to have an upper limit of about 130˚C – and for good reason. The intense heat disrupts vital molecules, and even with a host of repair and protection mechanisms, DNA and proteins start to unravel and disintegrate if they are subjected to temperatures much in excess of 120˚C.

Suppose we find nothing living between 130˚C and 170˚C in a deep-ocean volcanic-vent system, but then discover microbes thriving there between 170˚C and 200˚C? The discontinuity in temperature range would be a strong indicator that we were dealing with weird life as opposed to standard life that had simply pushed the temperature envelope higher.

[…]

There are plenty of other places that could be home for isolated weird extremophiles. The inner core of Chile’s Atacama Desert is one place – it is so dry and oxidising that bacteria can’t metabolise. The U.S. space agency NASA has a field station there, but so far there is no evidence for any carbon chemistry that could be attributed to weird life.

Other possible locations include the upper atmosphere, cold dry plateaus and mountain tops (where high-ultraviolet flux is a problem for standard life), ice deposits at temperatures below -40˚C, and lakes heavily contaminated with metals toxic to known life. We don’t need to confine our search to a single parameter such as temperature; it’s possible that some combination such as temperature and acidity together is more relevant.

Very speculative stuff, as science goes: it’s basically hinging on the old “white crow” aphorism, which says that the fact that you’ve never seen something doesn’t prove that the thing doesn’t exist. But we’re friends of informed speculative science around these parts, so… 🙂


Why we should clone a Neanderthal

Paul Raven @ 20-07-2010

Earlier in the year, there was some discussion over the possibility of cloning Neanderthals from archaeological remains. Now Kyle Munkittrick of Discover Magazine‘s Science Not Fiction blog speaks out in favour of the idea:

Knowing where Neanderthals fit, however, also creates a problem. What do we do if what makes humans “human” isn’t from a “human” at all? How do we justify “human rights” in light of evidence that our rational and moral minds are in no small part the result of prehistoric crossbreeding? In short: if human rights are based on being human, what rights would a cloned Neanderthal have?

The problem is, of course, that we don’t have a cloned Neanderthal. Which is why we need to make one.

[…]

To assert that the Neanderthal is between human and animal and is therefore an impossible fit for our world simply not true. The line between human and animal is blurred. Dolphins, whales, chimps, great apes, and other species are already changing the way we think about intelligence and rights; perhaps a Neanderthal, fully developed but so mentally different as to be incompatible with our way of living is the very example our society needs to change our perception of intelligent non-humans. When the technology is safe and the ability to nurture and care for her in place, we owe it to humanity as a whole to clone a Neanderthal and see what wonders she might teach us about ourselves.

There’s no simple answer, of course. Much as a cloned Neanderthal might teach us a great deal about ourselves, responsibility for his or her happiness and well-being would have to come first: to do otherwise would be to derail the essentially humanist thrust of Munkittrick’s argument. Human or not, a Neanderthal would be a sapient being, and quite likely more than capable of understanding that they were created for the sake of science… a lab rat that knew it was a lab rat, in other words. It’s a fascinating intellectual exercise to imagine how it might work out, but to actually do it?

All I can say is that as much as I’d love to learn how much of what we call being human is a cultural artefact as opposed to a biological phenomenon, I don’t know that I’d be able to take responsibility for the decision to create a living creature that might never feel it was living a life that made sense.


Laboratory lungs are go

Paul Raven @ 25-06-2010

Almost exactly a year back, we mentioned that biologists were looking into the possibility of growing simulated lungs to use instead of rats for toxicology testing procedures. Today, The Guardian reports that working prototypes of these cheap and ethical lung analogues are well in hand. (Warning: article includes use of the colloquial “[x]-on-a-chip” buzzphrase which, if you’re anything like me, makes you want to punch kittens and cuss at nice old ladies.)

The work at Harvard will be used mainly for studying the workings of living lung tissue without having to open up people or animals. It could also be used to test the effects of environmental toxins or new drugs.

The lung-on-a-chip could predict how human lungs absorb airborne nanoparticles and mimic the inflammatory response triggered by pathogens, said Donald Ingber, the vascular biologist who led the work at Harvard University’s Wyss Institute.[…] The device was able to replicate many of the natural responses of lung tissue, such as detecting pathogens and speeding up blood flow so that immune cells can deal with the invaders.

And in the rather select category of “news also involving biology, lungs and rats”, a team at Yale has grown new rat lungs and patched them into test subjects, who are reportedly breathing just fine [via SlashDot]:

The team started with decellularized adult rat lungs, which retain the organs’ branching airways and blood vessel network, and added a mixture of lung cells from newborn rats. Niklason says that the crucial step was nurturing the would-be lungs in a bioreactor that circulates fluid—simulating what would happen during fetal development—or air through them. The cells stuck to the scaffold in the right locations and multiplied. After up to 8 days in the bioreactor, they had coalesced into what the researchers’ tests indicated was functional lung tissue.

How long until we can buy off-the-shelf replacement organs? Will they ever be cheaper (or more reliable) than back-street “donor” options sourced from underprivileged populations?


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