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Earth May Harbor a Shadow Biosphere of Alien Life
An anonymous reader sends us to Cosmos Magazine for a speculative article arguing that a 'shadow biosphere' may exist on Earth, unrelated to life as we know it. If such non-carbon-based life were found here at home, it would alter the odds for how common life is elsewhere in the universe, astrobiologists say. "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 [it] was under their noses. ... Scientists are looking in places where life isn't expected — for example, in areas of extreme heat, cold, salt, radiation, dryness, or contaminated streams and rivers. [One researcher] is particularly interested in places that are heavily contaminated with arsenic, which, he suggests, might support forms of life that use arsenic the way life as we know it uses phosphorus."
It's life, Jim. But not as we know it.
Or the researcher is secretly needing arsenic to do his more brilliant colleague in the old Victorian-era way, having learnt from too many Agatha Christie novels.
Interesting theory, but I seem to remember my biology teacher discussing silicon-based life, and how it was much less likely to develop as carbon atoms produced much more stable molecules, especially on planets like Earth with water and nitrogen/oxygen atmospheres. Carbon-based life just "works" better on Earth.
On planets with radcially different environments there's probably a lot of potential for life that's totally different from ours, but I think it's fairly unlikely for us to discover it here.
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After a lengthy, one-sided dialogue with the nearest rock, I conclude that your theory is false.
Always going forward, 'cause we can't find reverse.
After many zen practitioners' lengthy, two-way dialogues with rocks near and far, your test criteria seem to be flawed.
You both have a point. The question is, where do you draw the line at what is life? Rocks may not have DNA or intelligence, but they do form, change, multiply and there's a recognisable process for destroying them. In a sense, rocks are a lot like the most basic forms of life that ever formed.
Let's be a little more serious now. Rocks around here probably won't ever advance beyond mimicking some very shaky comparisons to the most basic forms of life. But that doesn't stop us wondering if we're just seeing it on too small a scale to make that judgment. Perhaps it's safer to treat rocks as a failed attempt at life, one that happens too slowly to ever get beyond basic chemical reactions and simple molecular structures.
If it weren't for carbon-based life, who knows?
http://www.newscientist.com/article/mg19826533.600-early-life-could-have-relied-on-arsenic-dna.html tried looking up some examples of non carbon based life on earth that I'd heard of but couldn't find any however the ecology of undersea volcanic vents pretty much threw most ideas about heat tolerance and toxins being a problem out of the window.
Build a Man a Fire, and He'll Be Warm for a Day. Set a Man on Fire, and He'll Be Warm for the Rest of His Life.
You both have a point. The question is, where do you draw the line at what is life? Rocks may not have DNA or intelligence, but they do form, change, multiply and there's a recognisable process for destroying them.
Rocks do not have gaseous exchange (breathing) nor reproduce (cracking a rock to make two is _not_ reprodction). However, there is no definition of life that fire cannot meet, which the mule can. In other words, any non-contrived definition of life that includes the mule must also include fire. Here is a very basic explanation: http://simple.wikipedia.org/wiki/Life
It is dangerous to be right when the government is wrong.
You can't swap silicon for carbon in DNA. Silicon doesn't have the same talent for directionally bonding to itself. You can get get multiple bonds if you stick an oxygen in between, but the oxygen always has electron pairs that make it open to attack. There is no equivalent of the stable and inert paraffin chain.
If you were to have silicon-based life, then it would probably not use chain molecules. Suppose you had a planar silicate structure that catalysed the formation of a similar layer on top of it. The layers might then separate or exfoliate and then catalyse other copies of themselves. Some formations would be more stable, or would come out of solution at lower concentrations, and thereby 'predating' on less successful conformations by lowering the conentration of valuable components, and causing the other to go back into solution.
This is pretty dull sort of life - it isn't really much more than crystallization. No antennae, no ray-guns, no 'greetings earthlings, we come in peace'. However, carbon-based life was probably a pretty dull affair before the cell wall. It would have relied on random variations in ambient chemistry and temperature to do anything, and a lot of time must have been spent waiting for the right conditions for the next move. The simpler viruses are more like big chemicals than small creatures.
I remember a Scientific American article from about 1983 where it was argued that some of the lamellar structures that you can get in pre-cambrian clays may have been just such a system. No easy way of telling now, of course, because carbon based life would probably have killed it off. If it could be said to have been alive in the first place.
"They're made of meat."
"Meat?"
http://home.earthlink.net/~paulrack/id82.html
I have to question the standards of a Wikipedia article entitled "Life" that ends with a section on life insurance that makes up 1/8th of the article.
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"Alien" means "not from here." If our planet harbors a resident life form which we're not aware of, that doesn't make them alien. It just makes us ignorant.
It's not a lie. It's the truth with lossy compression.