Wednesday, January 26, 2011

'Arsenic and Old Lakes' - What a Catchy Title!

The Lemming generally posts micro-reviews about items that are available online to most folks who read English. This time, though, the Lemming isn't going to discuss this post on the KQED website:

"Arsenic and Old Lakes: NASA Finds Life NOT As We Know It"
Ben Burress, Quest blog, KQED (December 3, 2010)

Well, not much more than this excerpt and a few more words:

"...A bacterium has been found in the arsenic-rich environment of Mono Lake; a microbe that has the ability to substitute arsenic for phosphorous in its biochemistry, phosphorous being one of the essential elements for life as we know it (to which arsenic is toxic). While it is an Earthly microbe, the opening comment of the announcement was that this is NOT life as we have known it. (Funny—NASA's search for life on other planets has been for 'life as we know it,' and here they find an example of another sort right here on Earth….)

"I realize NASA's talking chemistry and not psychic alien embryos that latch onto your spinal column…but this is pretty awesome.

"Though it isn't quite the same as the eventual announcement of the discovery of extraterrestrial life (which I can see happening at some point), the ramification of this homeland discovery that most excites me is how it 'widens the lens' of our view on possible environments in which we might find life in the Universe...."

Mr. Burress makes a good point, although the Lemming thinks he should have been a trifle clearer about how much the Mono Lake organisms are "of another sort" of life. More about that, later.

On the 'up' side, the Lemming thinks Mr. Burress is spot-on when he notes that finding organisms that use arsenic where most terrestrial life uses phosphorous "widens the lens." The Mono Lake organisms are, in the Lemming's opinion, a loud wake-up call for NASA and anyone else seriously interested in finding life that doesn't live on Earth. Life on other worlds will quite probably not be quite like life on Earth.

The Lemming is reminded of Victorian-era English gentlemen of learning - many of whom, we're told, didn't see folks like the Hottentot as not quite human. Not only did they not look British: they didn't wear the sort of clothes proper Britishers wore, or live in cities.

A Digression: Why "Hottentot" isn't So Hot

The Lemming is aware, by the way, that folks aren't supposed to use the word "Hottentot." It's racist or something. However, since the Lemming doesn't know which word or phrase is politically correct this month: it stands as written. The Lemming apologizes, however, for offending sensitive readers: particularly those traumatized by words beginning with "h," or containing nine letters.

Back to Arsenic, Critters, and Scientific Blind Spots

Folks in the Western world have a different set of weird (in the Lemming's opinion) ideas these days. Happily, we've gotten it through our heads that not everybody has to look and act exactly the way our friends do, to be considered 'real' people.

The Lemming thinks the presumed biases of those Victorian gentlemen should be approached with the same consideration we're required to give [insert current term for non-western cultures].

Those gentlemen didn't get out all that much, it seems: and for the most part quite simply didn't have all that much contact with folks who didn't belong to their clubs; let alone lived half a world away. They, naturally enough, assumed that their little circle of acquaintances were 'normal.' And that everybody else - wasn't.

That didn't make their cultural myopia right - and that's another topic.

Scientists who designed the Viking life experiments, decades back, knew that Mars wasn't like Earth. We'd already gotten data back from the Mariner probes - and knew that the real Mars wasn't much like Burrough's Barsoom. Which, in retrospect, makes their experiment's design seem - odd.

What the Viking lander did, you see, was scoop up Martian soil, dump it in a container: and subject the stuff to conditions that were ideal for microorganisms that live in the soupy, hot, waterlogged, oxygen-nitrogen mixture that we're used to.

What happened next was dismissed as 'peculiar chemistry.' It wasn't until recently that a scientist who understood biology - and that Mars isn't Earth - worked out a metabolism that would have produced those odd readings. (March 5, 2009)

Maybe Mars doesn't have any indigenous life - and that the 'peculiar chemistry' was just that. Or maybe we need to 'widen the lens' a bit, and acknowledge that critters that live in thin, dry, CO2 probably don't have quite the same metabolisms as critters that live on our hot, wet, oxygen-rich planet.

Arsenic and Old Lakes - Another One

That KQED title was quite catchy - and showed up again, in the March 2011 issue of Sky and Telescope magazine. The Lemming would provide a link to the article - but it appears in the print edition. And, the Sky and Telescope nifties are a sort of members-only thing.

Anyway, here's an excerpt:

"Arsenic and Old Lakes"
David Grinspoon, Cosmic Relief, Sky and Telescope (March 2011) (That's what the issue says)

"What does the discovery of arsenic-eating microbes really tell us about finding life elsewhere?

"...Researchers working in the Mono Lake area of California had found microbes that, unlike any other known organism, seem to use arsenic instead of phosphorus in DNA and other crucial molecules. This is important because astrobiologists often list the biogenic elements - carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus - as essential for life anywhere.

"...But if these critters can actually use arsenic where the rest of us need phosphorus, does this really have huge implications for the search for alien life?

"Yes and no.It's certainly an expansion of life's known limits and chemical bag of tricks. But these microbes are still carbon based. ...they use giant carbon molecules to build cells and carry information. They reveal the edges of Earth's biosphere to be a bit wider than we imagined...."

"...The discovery may actually help astrobiologists resist an intellectual trap. At the press conference there was discussion of how to alter future missions to Mars or elsewhere to search for arsenic. But that's the wrong lesson. We don't need to start looking specifically for arsenic on other planets. Rather, the take-home message should be that we cannot assume we know what the biogenic elements are. Any of them...."

In the Lemming's opinion, Mr. Grinspoon is on the right track. The trick would be to devise an experiment that would detect life - even if it was radically different from Earth's.

The Lemming thinks carrying along a microscope would help - on the principle that critters move. At least inside their cells. Now, that assumes that all life forms cells - which the Lemming thinks is likely - and that's close to getting into another topic.

Related posts:More in this blog:


Brigid said...

Missing third-person pronoun: "Mr. Burress is spot-on when notes that"

Wrong planet? "Put Titan in orbit around a planet in the same planetary system as Mars"

The Friendly Neighborhood Proofreader

Brian, aka Aluwir, aka Norski said...


Fixed the third-person pronoun thing.

About "Put Titan in orbit around a planet in the same planetary system as Mars" - The article I referred to said, quite clearly, that Titan was a moon of Mars.

Titan orbits Saturn. Same planetary system - the one we live in, different planet.

I think the mistake is understandable. Pictures from Mars show a place with reddish soil - and a reddish-pink sky when it's dusty. Titan, as seen from the surface, is reddish.

Someone who got his science education in America's government schools might not realize that there's more than one place in the soil that's largely reddish as seen from the surface. Or assume that since Mars is reddish, any reddish moon has to orbit Mars.

Or maybe the SNAFU was a result of deadline pressure and a hasty glance at pictures.

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