Is it possible that any life on earth could evolve to live off a liquid which is not water? Something like oil or some other natural liquid?
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asked Dec 1, 2014 at 10:45
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$\begingroup$ One of the functions of water is to be a solvent. Maybe if a lifeform is resistant to ethanol or some other alcohol, that could be used instead? I don't know how plausible this is, so I will refrain from answering. $\endgroup$– kutschkemCommented Dec 1, 2014 at 12:44
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3$\begingroup$ These questions are tricky to answer because "life" does not have a clear-cut answer. Whether life could evolve without water is very dependent on what your personal definition for "life" is. $\endgroup$– Cort AmmonCommented Dec 1, 2014 at 15:20
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$\begingroup$ Are you asking if life existing on Earth could adapt to completely different medium, or if another abiogenesis could have happened in other medium? $\endgroup$– IrigiCommented Dec 2, 2014 at 10:20
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$\begingroup$ @kutschkem If this were possible, the Irish would have evolved this already... :) $\endgroup$– AndyD273Commented Mar 25, 2015 at 18:23
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$\begingroup$ WC Fields researched this question quite intensively during his spiritual journey thru life. $\endgroup$– theRileyCommented Nov 10, 2018 at 16:56
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3 Answers
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Water can be substituted with liquid Ammonia (NH3) which has many chemical properties which are similar to water and can fulfill most of the roles which are usually fulfilled by water in organic chemistry.
Ammonia is liquid between -80° C and -30° C. So an ammonia-based biosphere would only be possible on worlds much colder than Earth (or with an atmosphere with a much higher pressure).
However, Ammonia has a problem: It is flammable. When there would be an ocean of Ammonia on a planet with an oxygen atmosphere (and don't think you can get rid of oxygen that easily), one spark would ignite it. Burning ammonia becomes nitrogen and water-ice. So most larger ammonia lakes would likely be below an ice layer.
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3$\begingroup$ If life was evolving from Ammonia, would there necessarily be plants producing large amounts of Oxygen? Free Oxygen doesn't like to exist by itself and tends to Oxidize something. $\endgroup$ Commented Dec 1, 2014 at 17:06
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$\begingroup$ @bowlturner Likely yes. Replacing oxygen with something else would be another huge change in organic chemistry. Exploring whether or not this might be possible would be stuff for another question. However, you will always need some oxidizing agent which likely would also oxidize ammonia. $\endgroup$– PhilippCommented Dec 1, 2014 at 20:54
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$\begingroup$ I won't argue that, but ammonia is very different from water. I guess my point was if something isn't producing O2 then some other chemistry will need to be happening. $\endgroup$ Commented Dec 1, 2014 at 21:00
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$\begingroup$ @bowlturner - questions like this make me wonder if the earth started as ammonia and oxygen and became the nitrogen water mix that we have today by this process. Any oxygen on this planet would ultimately result in a atmosphere not unlike earth, no? $\endgroup$– TwelfthCommented Dec 2, 2014 at 0:33
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$\begingroup$ @Twelfth my chemistry is too rusty to have an answer for that. $\endgroup$ Commented Dec 2, 2014 at 13:37
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No, water based life could not swap solvents to ammonia or hydrocarbon. It's far to big of a jump to make. The closest that might happen would be that chemicals from water based biology might be part of biogenesis in a different medium. This would require dumping a significant mass of water based biomatter into an environment with large amounts of liquid ammonia or methane.
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$\begingroup$ but there are archaea on earth which have evolved to use methane instead of water $\endgroup$– zackitCommented Feb 11, 2021 at 16:42
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$\begingroup$ @zackit I can find plenty of references to archaea producing methane but not to archaea that use methane as a solvent within which their core biochemistry occurs. Do you have a source you can point to? $\endgroup$– smithkmCommented Feb 12, 2021 at 18:43
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An organism that doesn't require water is called a xerophile. Endoliths -- http://www.wikiwand.com/en/Endolith are one example. They live off iron, potassium, or sulfur. Pretty sure there are lots of bacteria that don't metabolize water. And we've witnessed bacteria develop entirely new metabollic pathways. Nylonaise for instance, evolved to metabolize nylon, Escherichia coli evolved a metabolic pathway for ethylene glycol: pathway http://www.ncbi.nlm.nih.gov/pubmed/6336729
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$\begingroup$ Metabolize == food, not water. Make sense? $\endgroup$– JaxCommented Apr 30, 2015 at 13:53
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$\begingroup$ Yes, xerophiles can live with little water, but not with no water at all. $\endgroup$ Commented Jan 10, 2016 at 22:02