Is water really necessary for life?

[ISamson]

You know how they always say that without water there would not be life, right?
Astronomers also look for life on planets with hints of water in their spectrum. But is water really necessary for life? Some ET life could not be a tiny bit similar to ours and might not even need water or water could harm the life, potentially.
What is the chemical importance of water to life, that I don't understand? Is there something I don't get?
Thank you.

 

[QuantumQuest]

You know how they always say that without water there would not be life, right?
Astronomers also look for life on planets with hints of water in their spectrum. But is water really necessary for life? Some ET life could not be a tiny bit similar to ours and might not even need water or water could harm the life, potentially.
What is the chemical importance of water to life, that I don't understand? Is there something I don't get?
Thank you.

Water has several chemical properties that make it indispensable for life. A molecule of water is simple but it has polarity, due to the fact that the atoms of hydrogen are on the one side creating a positive region while oxygen on the other side has negative charge. This makes water the kind of universal solvent that it is. Going further, water due to its dissolving properties is an appropriate medium for the transmission of substances into or out of a cell. Another important feature of water is that it can exist as solid, liquid and gas in a range of temperatures and pressures that is not too wide. It is one of few materials in this respect and the importance of it is that it creates the sort of habitats and microclimates we experience on Earth . Also, water may be the carrier of building blocks of life on Earth according to some theories.

Now, on the other hand, there could be life forms that don't rely on water. As far as I know, methane is a potential candidate, as it is a dissolvent but it is found in liquid form at very low temperatures and ammonia.

 

[gianeshwar]

Water is needed for life like ours.There may be another form of life which does not need water.Here life needs to be defined in general if possible first.

 

[anorlunda]

Isaac Asimov wrote extensively about alternate chemistry for life other than carbon. Sulfur-based life was one. His conclusion was that there are many obstacles for all the alternatives.

Isaac Asimov (Winter 1981). "Not as We Know it – the Chemistry of Life". Cosmic Search. North American AstroPhysical Observatory (9 (Vol 3 No 1)).

See also https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry

Asimov also pointed out another vital property of water. Water is the only (nearly only?) substance who's ice floats. Most substances, when they freeze the ice sinks to the bottom. If water ice did not float, then the Earth's oceans would have frozen from the bottom up and there would be almost no liquid water on Earth.

 

[phinds]

You know how they always say that without water there would not be life, right?
Astronomers also look for life on planets with hints of water in their spectrum. But is water really necessary for life? ...

Very interesting question and one I've wondered about as well. It will be interesting to see what comes up in the thread. I like QuantumQuest's suggestion that methane might work.

Here's some information:
https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry

 

[gianeshwar]

Carbon having four bonds is considered a wonder for our life .Still we can say that it is all by accident.Though there are explanations may be unscientific by Two anthropic principles.

 

[Delta2]

Main property of water that seems to make it a necessity for life is that it is a universal solvent. Even in a single cell thousands of chemical reactions happen every minute, those reactions just wouldn't happen so easily and effectively without a proper universal solvent.

Maybe there can be microscopic life forms that do not consist of water at all, but I believe for larger organisms like humans , who should have a circulatory system (i.e blood and veins and heart) I can't think of any other fluid that has all these properties needed for proper circulation (our blood plasma consists of 92% water).

 

[anorlunda]

Main property of water that seems to make it a necessity for life is that it is a universal solvent.

5Non-water solvents

• 5.1Ammonia
• 5.2Methane and other hydrocarbons
  • 5.2.1Azotosome
• 5.3Hydrogen fluoride
• 5.4Hydrogen sulfide
• 5.5Silicon dioxide and silicates
• 5.6Other solvents or cosolvents

No doubt none are as good as water, but might they be possible? One has to consider the environment (especially temperature) and the availability of elements.

 

[gianeshwar]

Is water the only liquid in universe which has 4 degree as a special temperature and hence make aquatic life possible?Our origin of life is also acquatic.

 

[ISamson]

From the Wikipedia article:

If life exists on other planets or moons, it may be chemically similar; it is also possible that there are organisms with quite different chemistries[3]—for instance involving other classes of carbon compounds, compounds of another element, or another solvent in place of water.

What about if life consists not of carbons, but of completely different compounds, like boron or potassium (random examples). These chemicals have completely different properties to carbon, but who knows what some other life could adapt to? Some other life might not have evolved just like ours. The possibilities might be endless.

 

[jim mcnamara]

Moved to Biology forum.

 

[gianeshwar]

In cell biology membranes are probably semi perpeable.And there are concentration gradients created to allow certain things cross and certain not to.Fish also are classified as salt water fish and fresh water fish andd many other forms of life where osmotic pressure contributes to life propagation.

 

[gianeshwar]

Now basic question remains to be exactly answered "What is life"before asking need of water even.

 

[Bystander]

See https://en.wikipedia.org/wiki/Stellar_nucleosynthesis , and, https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements ; recall chemical formula for water, and proceed with caution.

 

[Delta2]

Now basic question remains to be exactly answered "What is life" before asking need of water even.

That's a simple stated question that has no simple but very complex answer. Actually the answer to this question is still an open debate between biologists, physicists, chemists and philosophers. Wikipedia focuses on the biological definition of life https://en.wikipedia.org/wiki/Life#Biology. This definition gives a list of 8 traits that "something" should have in order to be characterized alive.

Some may argue that all these 8 traits can be achieved even if "something" doesn't use water as universal solvent and some may not.

I may repeat myself but I still think that for large organisms, large enough that a circulatory system is a necessity, I find it hard to grasp that in their veins will be flowing something else that is not based of water (as I said before blood plasma is 92% water).

 

[ISamson]

I may repeat myself but I still think that for large organisms, large enough that a circulatory system is a necessity, I find it hard to grasp that in their veins will be flowing something else that is not based of water (as I said before blood plasma is 92% water).

Ok, correct, but what if an Extra-Terrestrial organism had some other chemical flowing though their veins other than blood?
What if some ET life would not even need anything flowing in their veins?

 

[Jacinta]

For Earth life forms, yes.

But an alien being who can adapt to their planet without water or oxygen probably doesn't need it.

 

[jim mcnamara]

In response to several posts that appear to be mostly personal theory, consider reading what scientists understand. And yes some of it is guesswork. But a lot of the concept involves Chemistry which anyone can duplicate in a lab.

Then we can all be on the same page.

*Abiogenesis is the term. And it requires a lot of liquid. The best candidate for Earth is water. This also the reason NASA plans to send a probe to Enceladus, a moon of Saturn.
See:

*https://en.wikipedia.org/wiki/Abiogenesis <- please read this first.
Please stop guessing or the thread will be closed.

 

[DaveC426913]

There are about a dozen properties of water (some already mentioned) that make it an excellent ingredient for life. While this doesn't rule out other molecules, it sure gives water a giant head start.

It is very abundant in the universe.
Its components are abundant.
It is one of the very simplest of molecules.
Its components have an extremely high affinity for each other.
It is polar, which makes it a good solvent.
It has a broad range of temp in which it is liquid.
It has a very high heat capacity.
Its solid form floats on its liquid form, meaning ice forms from the surface down, protecting lower layers from further freezing.

The list goes on.

Each of these is conducive to life, and they are cumulative.

 

[Delta2]

Ok, correct, but what if an Extra-Terrestrial organism had some other chemical flowing though their veins other than blood?

Well, I think we can't exclude this possibility (it just seems unlikely to me, I am not a biologist though), maybe for example there can be liquid methane or ammonia flowing in veins of some alien.

What if some ET life would not even need anything flowing in their veins?

I can't think of a "large" organism that doesn't have some sort of circulatory system and fluid but ultimately we can't exclude this possibility either, for example if there are some sort of "veins" that are like coaxial cables or optic fiber and the EM field or some unknown to us field, propagates in these "veins".

 

[Dr_Zinj]

Now basic question remains to be exactly answered "What is life"before asking need of water even.

Simplest answer is that to have life, something needs to be able to:
(1) Grow
(2) Reproduce
(3) Seek out resources to support (1) and (2).

 

[r8chard]

Personally I do not see the point of this discussion. The only correct answer to the original question is "Maybe?"

Until we find examples of non-Carbon, non-Water based lifeforms, we are all speculating.

Perhaps, eventually a research laboratory will manufacture such a novelty. That still would not prove that such lifeforms can naturally exist in this universe.

 

[Buzz Bloom]

Simplest answer is that to have life, something needs to be able to:
(1) Grow
(2) Reproduce
(3) Seek out resources to support (1) and (2).

Hi Dr_Zinj:

If I understand this correctly, a virus satisfies these three requirements. Whether a virus is alive or not is a question about choices of definitions rather than about biology. Also, I understand the question is answered differently by scientists who's fields of interest are different.

I tend to favor a definition that requires a life form candidate to have as a component a boundary between the life form and its environment, e.g., like a cell membrane. (A virus also has such a boundary.) Furthermore, the boundary needs to be created and maintained by the organism's chemistry, rather than by the environment's chemistry. A virus does not satisfy these additional two constraints.

Regards,
Buzz

 

[TeethWhitener]

Simplest answer is that to have life, something needs to be able to:
(1) Grow
(2) Reproduce
(3) Seek out resources to support (1) and (2).

This suggests that a forest fire is alive.

Edit: It also suggests that a mule is not alive.

 

[DaveC426913]

Please stop guessing or the thread will be closed.

 

[DaveC426913]

This suggests that a forest fire is alive.

No, the term is being used ambiguously.

Reproduction in a biological context means storing a blueprint of itself and making viable copies.

Fire can only reproduce metaphorically (i.e. a superficial similarity). Which is why we say fire is metaphorically alive.

 

[BillTre]

Life on Earth is possible without water, but only in a suspended state (tartigrade example), if you call that living.
If you don't call that living, then you are admitting the creation (or recreation) of life when the water is added back.
Ongoing (non-suspended) life in Earth does not happen without water. The chemistry just stops (mostly, see below).

The (unstated) reason so many people mention water is a universal solvent is that life processes involve lots and lots of specific chemical reactions. Molecules dissolved in solution allow this chemistry to occur more rapidly and let components not originally found next to each other (where they could react) to get near each other. This would not happen (or not as well) if the chemistry were based on solids rather than solutions. Reactions between two solids would only occur at their touching surfaces (unless large amounts of energy were released which could pulverize, liquify, or vaporize the chemicals).

Edit: It also suggests that a mule is not alive.

Presumably you mean that this is due to its not being able to reproduce.
However, a mules cells do reproduce themselves, within the animal.

WRT viruses and being alive:
Viruses, or any life form we are aware of, need the proper environment in order to survive and reproduce. Without the proper environment, no life form will survive.
Important parts of many cells environments include the proper environmental parameters, nutrients, and a variety of other things.
Important parts of a virus's environment include living cells to parasitize (actually, the cells own controlled internal environment).
Important parts of a parasite's environment also include their hosts.

While I could argue (based on choice of definition) that viruses are either alive or dead, I don't know if I would feel right about ruling them out based on lacking an anatomical feature in a discussion about the hypothetical existence of life forms differing from the only kind of life we are aware of.

The problem of this whole discussion (which I am kinda enjoying) is the lack of a good general definition of life that a lot of people like and that could be applied to life forms foreign to our current awareness (basically already stated).

On the other hand, I think the possession of a cell membrane was important to the original evolution of life (as we know it, on earth) since it allowed a genetic information system to control its essential internal environment (essential for how the genetic system maintains itself) separately from that of other competing genetic systems.

Other potential forms of life differing from what is on earth, might take any number of possible forms and all that is speculation (as several have already said).
A sci-fi favorite alternative life form of mine is based something like interacting electromagnetic entities in the plasma of stars rather than chemistry.

 

[jim mcnamara]

Since we do not have a functioning working definition of life, and clearly folks disdained reading a good starting point mentioned above, we come to an ending point

Thread closed.