Life May Have Evolved In Ice

Philip Bailey writes "An article in this month's Discover Magazine claims that some of the fundamental organic molecules required for the development of life could have spontaneously arisen within ice. Scientist Stanley Miller was responsible for seminal experiments in the 1950s in this area. He used sparks and a mixture of inorganic chemicals to test his theories, but turned to low temperature experiments in later years. He was able to create the constituents of RNA and proteins from a mixture of cyanide, ammonia and ice in trials lasting up to 25 years. A process known as eutectic freezing is thought to be the basis of these results: small pockets of liquid water, in which foreign molecules are concentrated enormously, increases the reaction rates, and more than compensates for temperature-related slowing."

Ice...

[icegreentea]

Was the earth even cold enough back then to have that much ice? My understanding is that life began about 3 billion years ago, and that Hadean Earth pretty much lasted until then.

Some say that life evolved in fire...

[lennier]

Some say in ice
From what I've tasted of desire
I hold with those who favor fire
But if it had to bootstrap twice
I think I know enough of genes
To say that for mutation ice
Is also keen
And would suffice

Re:Why so few cryophiles?

[Cassius Corodes]

That's a very good point - given that the simplest life forms we have found so far (in terms of the length of the dna) are ones that are evolved for normal (ie-non icy) conditions. However its interesting to note that for most bacteria being frozen is not lethal (although I'm not 100% sure on this), rather it just stops doing anything until it thaws and then continues on.

Re:Why so few cryophiles?

[OzRoy]

Unless the Earth experienced a 100% ice-free period, descendants of those original cryophiles would be with us to this day.

I believe that is the case. A few very large volcanic eruptions increased the CO2 and caused high temperatures and no polar ice caps. I think this is one of the theories as to why we have such large oil deposits. Without the polar ice caps the ocean currents stopped flowing, and the CO2 in the atmosphere was removed very slowly by algea that died and sank to the ocean floor and in the right areas were trapped and converted into an oil deposit.

Of course it is a little bit more involved than that and this is only my vague layman understanding. Someone else can fill in all the details.

Oxygen Catastrophe?

[Cybrex]

I'm in no way qualified to even speak on this subject, but could it be that the Oxygen Catastrophe [en.wikipedia], in wiping out the great majority of life on Earth, provided sufficient selective pressure that any previous bias toward cryophilic life was effectively erased? I'm just speculating wildly here.

Re:Why so few cryophiles?

[Zebraheaded]

From what I remember, there's been a fair amount of species found that have developed a tolerance for cold temperatures; but there's been very limited results of research into obligate psychrophiles, which would have more likely evolved in a cold environment. I think this field is one of those areas of bacterial research that is going to be very slow in developing due to the incredible difficulty of culturing these kinds of organisms in vitro. One of my old professors published a very interesting paper on finding ways to isolate these difficult organisms: http://www.sciencemag.org/cgi/content/abstract/296/5570/1127?ijkey=2zqckfPCzt9z2&keytype=ref&siteid=sci [sciencemag.org]

Re:Ice...

[Tablizer]

One of the ongoing problems in paleobiology is the "early quiet sun". Solar models, which we now know to be extremely accurate based on solar neutrino measurements, show that the sun was considerably dimmer in the distant past. So dim that by any reasonable standard we would expect the Earth to be substantially covered with... ice.

Yes, but the atmosphere makeup has a big effect also, and the nature of the early atmosphere is still up in the air (pun). The planet itself was also warmer back then due to active volcanism from a closer moon and heat left over from formation.
     

Re: Why so few cryophiles?

[Anonymous Coward]

I am assuming that this theory only really applies to biological precursors; perhaps embedded within the icy crust of comets or asteroids. Although the Sun at this time was likely only putting out 70% as much energy as it does now, Earth at the time was likely still very hot from the near constant bombardment from large chunks of rock falling from the sky, and the larger amount of radioactive materials sinking into the planets core. I would also imagine that large amounts of whatever chemicals they were carrying would survive, effectively seeding the Earth with some of the materials needed for life to evolve.

I seem to recall that nucleic acids were unlikely to form in the conditions some think were present on the early Earth (A dense CO2/N2 atmosphere with little in the way of liquid water), so if these processes occured in comet ice that could be a nice way to get around the problem of suboptimal conditions on the Earth itself. It would also be a nice fit with what you've said about the lack of evidence of cryophilic from ages past if life evolved on a hellish Earth with some of the ingredients coming from icy mountains thrown from the heavens.

-TJT