Life not as we know it... How do we find it?

[Moontanman]

This article reminded me of how difficult it would be to actually find life that operated on some system other than the one we are familiar with.

 

http://www.the-scientist.com//?articles.view/articleNo/34328/title/Ice-Lake-Home-to-Life/

 

The deep antarctic lakes have finally been penetrated and the life forms that exist there will soon be under our scrutiny, such environments may be the best place to look for life forms not part of our "normal" biosphere, how would we go about detecting a life form that didn't use DNA?

[Ophiolite]

A personal add with a contact phone number?

[Moontanman]

Te he he he... I left off part of my post, i meant to mention the shadow biosphere concept... oops...

 

http://en.wikipedia.org/wiki/Shadow_biosphere

 

The shadow biosphere is a proposed biosphere made up of organisms that use a radically different biochemistry that currently know organisms. Some people have proposed that such organisms might be found in isolated or extreme environments and the environments below these ice lakes is indeed both...

[overtone]

Almost certainly, no place on Antarctica has been isolated long enough to have captured and preserved life forms so fundamentally and radically different from those found on the rest of the planet.

 

The predominance of RNA/DNA cell based life on this planet includes it having wiped out the competition (if any), treating it as food etc, billions of years ago.

 

One would look for local or defined area reversals of entropy, coherences maintained improbably for a long time, and then verify reproduction or spread (one could imagine an entity that simply grew, rather than reproducing, might count as being alive, eh?).

 

My nomination for where to look for currently unrecognized or unknown and radically different life forms on earth would be in large scale structures, places where we have missed the forest for the trees, the reef for the fish, the mountain for the rocks. I would expect it to be very primitive in its overall organization, far less sophisticated than a bacterium, as it has had little time (measured in generations, adaptive turnover opportunities, etc) to evolve.

[Moontanman]

Almost certainly, no place on Antarctica has been isolated long enough to have captured and preserved life forms so fundamentally and radically different from those found on the rest of the planet.

 

The predominance of RNA/DNA cell based life on this planet includes it having wiped out the competition (if any), treating it as food etc, billions of years ago.

 

One would look for local or defined area reversals of entropy, coherences maintained improbably for a long time, and then verify reproduction or spread (one could imagine an entity that simply grew, rather than reproducing, might count as being alive, eh?).

 

My nomination for where to look for currently unrecognized or unknown and radically different life forms on earth would be in large scale structures, places where we have missed the forest for the trees, the reef for the fish, the mountain for the rocks. I would expect it to be very primitive in its overall organization, far less sophisticated than a bacterium, as it has had little time (measured in generations, adaptive turnover opportunities, etc) to evolve.

 

 

I'm not sure if I agree, the shadow biosphere, if it exists, is thought to be wide spread and would not have emerged recently...

 

 

 

http://en.wikipedia.org/wiki/Shadow_biosphere

 

 

 

 

Shadow biosphere

From Wikipedia, the free encyclopedia

The term "shadow biosphere" was coined by Carol Cleland and Shelley Copley.^[1] A shadow biosphere is a hypothetical microbial biosphere of Earth that uses radically different biochemical and molecular processes than currently known life. While life on Earth is relatively well-studied, the shadow biosphere may still remain unnoticed because our exploration of the microbial world targets our biochemistry primarily.

Steven A. Benner, Alonso Ricardo, and Matthew A. Carrigan, biochemists at the University of Florida, argued that if organisms based on RNA once existed, they may still be alive today, unnoticed because they don't contain ribosomes, which are usually used to detect living organisms. They suggest searching for them in environments that are low in sulfur, environments that are spatially constrained (for example, minerals with pores smaller than one micrometre), or environments that cycle between extreme hot and cold.^[2]

Other proposed candidates for a shadow biosphere include organisms using different suites of amino acids in their proteins or different molecular units (e.g., bases or sugars) in their nucleic acids,^[1] a chirality opposite of ours, that use some of the non-standard amino acids, or that use arsenic instead ofphosphorus.^[3] Carol Cleland, a philosopher of science at the University of Colorado (Boulder), argues that desert varnish, whose status as living or nonliving has been debated since the time of Darwin, should be investigated as a potential candidate for a shadow biosphere.^[4]

 

 

[CharonY]

My take is that if there is a shadow biosphere, there will be metabolic traces that cannot be explained by abiotic processes. I am a bit sceptic on the biosphere on earth concept for two reasons.

First, life as we know it is incredibly efficient. The shadow biosphere would only be competitive under very exotic conditions. And second, as above mentioned, we have not found anything (afaik) that could have not been done with life as we know it.

 

The main argument of the proponents of a biosphere appear to be that DNA or rRNA based searches won't yield anything. That is kind of true, but they (often) neglect the fact that life also interacts with its surroundings which also leave traces.

 

Interestingly the proponents of the shadow biospheres are often not biologists and do not realize that many (if not most) biological disciplines are not limited to molecular biology (i.e. looking at proteins, DNA, RNA, etc.) but also study the consequences and interactions of organisms with each other and the environment.

Edited February 12, 2013 by CharonY

[Ophiolite]

Almost certainly, no place on Antarctica has been isolated long enough to have captured and preserved life forms so fundamentally and radically different from those found on the rest of the planet.

Although Antarctica has been hovering over the poles pretty much since the break up of Pangea. So that's a couple of hundredmillion years of partial isolation.

[overtone]

the shadow biosphere, if it exists, is thought to be wide spread and would not have emerged recently...

In which case it would be three billion years mixed in and well adapted to the competition from RNA/DNA based evolutionary product worldwide: as likely to be found today in, say, the dark cold water anoxic, high UV cold dry or wet , hot deep rock dark chemically extreme, and other such, that we have had long term access to since biology became a science - no need for, or obvious benefit from, a relatively short and recent isolation in a fairly common type of habitat to have "preserved" it.

 

Not saying it's impossible, that something about Vostok cannot possibly have released a lurking shadow world into more visible prominence, just that Vostok was part of the outer world for so long, and isolated so recently in microbiological terms, that one would expect to find strange and unique products of the biological world as it existed after nearly three billion years of evolution - the world surrounding us now, in microbiological terms. The micro equivalent of kangaroos and platypods and black swans, not silicon based acellular radio-frequency communicating balloon beasties, seems likely.

 

As far as how to find life completely new and different, life's signature is repeated establishments of wildly improbable and localized pockets of complexity, statistically inexplicable defiance of the 2nd Law. That should be visible to the alert in the material world, with indications from even crude observation - the oxygen content of the Earth's atomosphere, for example, can be detected from outer space.

Edited February 12, 2013 by overtone

[Moontanman]

In which case it would be three billion years mixed in and well adapted to the competition from RNA/DNA based evolutionary product worldwide: as likely to be found today in, say, the dark cold water anoxic, high UV cold dry or wet , hot deep rock dark chemically extreme, and other such, that we have had long term access to since biology became a science - no need for, or obvious benefit from, a relatively short and recent isolation in a fairly common type of habitat to have "preserved" it.

 

Not saying it's impossible, that something about Vostok cannot possibly have released a lurking shadow world into more visible prominence, just that Vostok was part of the outer world for so long, and isolated so recently in microbiological terms, that one would expect to find strange and unique products of the biological world as it existed after nearly three billion years of evolution - the world surrounding us now, in microbiological terms. The micro equivalent of kangaroos and platypods and black swans, not silicon based acellular radio-frequency communicating balloon beasties, seems likely.

 

As far as how to find life completely new and different, life's signature is repeated establishments of wildly improbable and localized pockets of complexity, statistically inexplicable defiance of the 2nd Law. That should be visible to the alert in the material world, with indications from even crude observation - the oxygen content of the Earth's atomosphere, for example, can be detected from outer space.

 

 

I think you make a good point, while i don't expect to see silicone life on the earth suddenly being found, Thomas Gold suggests there is evidence of it in his book "The Deep Hot Biosphere" but his evidence is circumstantial at best. What they are suggesting is that at some point there was more than one genesis of life and that other genesis might be different enough from DNA life that the tests we use for DNA life wouldn't detect this life but it would still be carbon based and be similar to what we recognize as life. so similar that "seeing" one of them wouldn't raise an eyebrow, only chemical tests could determine this life had no genetic connection with our type of life... This shadow biosphere would exist right along side our own and might even have a superficial connection with it, just not a connection of genetic descent...