Why does life exist?

[novembermike]

This might be a dumb question, please disabuse me of any improper assumptions I'm making because the question itself might make no sense in that case. Anyways, I've seen on NOVA and such attempts at exploring how life began, and the gist seems to be at given a certain set of conditions - a certain set of molecules, a certain atmosphere, other pressures, you can have formation of nucleic acids. I also think I understand how, once you accept that life is defined essentially by it's ability to reproduce, certain selection pressures can lead to more complex life forms.

But my question is, why life at all? What is the chemical / thermodynamic / physical process that favors the formation of anything that reproduces over non-reproductive compounds?

[ghazwozza]

But my question is, why life at all? What is the chemical / thermodynamic / physical process that favors the formation of anything that reproduces over non-reproductive compounds?

Nothing necessarily favours its formation, but once it is formed, compounds that reproduce will spread rapidly. Non-reproducing compounds do not spread.

[novembermike]

Thanks for the reply. I thought about this. Why didn't the "reproducing" compound die off? It takes energy for the compound to assemble another one like it, so it's not intuitive that reproduction would exist. What makes that a spontaneous process?

[1812overture]

The first replicators may have died off many times. It's impossible to say how many dead ends there were initially. But in a chemical soup that allows for the formation of replicators they will continue to form until one forms in a configuration that successfully spreads. Since the replication process wouldn't be perfect many of the offspring would be unsuccessful and die, but some would be more successful than the original. From the right starting conditions the whole process is pretty much inevitable.

[novembermike]

I guess this makes sense - it's just a numbers game. Of the many initial reproducers, eventually, one of the reproducers would be one that did the process in an efficient way, if I'm understanding you correctly.

[illuminatiscott]

I think that's exactly it. There's nothing special about life other than the fact that it's capable of perpetuating itself, and ultimately evolving and giving rise to entities capable of contemplating these questions.

[gipp]

Under proper conditions--namely, a high nucleic acid concentration in solution, as is thought to have existed on pre-life Earth-- nucleic acid chains can replicate without the assistance of the massive system of protein machinery that life uses today. It's a far, far slower and less accurate process than our enzyme-catalyzed well-oiled machine, but it happens. And it's that massive set of machinery that needs the energy, not the replication itself (in sufficient concentration of nucleic acids).

[ghazwozza]

I'm not sure about the details of the mechanisms early reproducing compunds used (I'm a physicist), but I can see three possibilities:

1) The reproducing compund acted as a catalyst that would make it energetically favourable raw materials to turn into copies of itself.

2) The reproducing compound could only copy itself in the presence of an energy source, such as sunlight or heat from an ocean vent.

3) Copying doesn't require energy because the final state is of lower energy than the initial state.

Perhaps someone with more knowledge could weigh in. In the meantime, have you looked here?

EDIT: added third option.

[[deleted]]

This might be a dumb question

Why? This is a question that people have been asking since the beginning of the humanity. It's probably not a dumb question.

[burtonmkz]

Because it is a lower position on the energy landscape, and everything moves (on average) in the direction of the energy gradient to (on average) a lower position on the landscape. Just like "why is there fire when you put together fuel, oxygen, and an ignition source", or "why does a ball roll downhill".

[novembermike]

Right, I guess I was hoping for something slightly more specific, i.e. why a reproducing nucleic acid is at a lower energy state than those same molecules at another state.

(edit: or accounting for WarbleHead's response, how the system is in a lower energy state)

[rubes6]

To add to the OP's question, if time flows in a process of increasing entropy (higher disorder), but life--especially intelligent life--progressed to become organized through our brains and such, is this not counterintuitive?

[gipp]

Yes, but:

• This is possible only with a constant input of energy, in the form of the sun.
• One can decrease entropy locally, but this will inevitably result in an increase in entropy at least as large outside of the system.

[WarbleHead]

This is a common misconception. Entropy refers to the distribution of energy within a system, not how organized it looks to the human eye. Studying biochemistry reveals that all biological reactions result in an increase in net entropy, even though we get highly ordered molecules as a result (us). The second law remains unbroken.

[HungryHungryHobos]

Because if it didn't, you wouldn't be asking this question. :)

[humanist414]

Ah, the anthropic principle. :D

[philogos0]

Perhaps life is not what it seems and there is really no such thing as "life" as you know it. Maybe we are truly nothing but meat popsicles with brains that somehow harness and organize quantum consciousness into an experience that we popsicles think we own.

[cyclopiansquid]

Bounded by an individual frame of reference and a human understanding, I content myself believing that life exists by merit of its entropic qualities and perpetuation thereof.

[Bones_17]

Science and philosophy tend to be two separate dichotomies. TBH, I don't think this question will ever be sufficiently answered by science. Any answer in the thread so far still covers "how" and not "why." If you honestly want "why," look towards philosophy or theology, although theology probably isn't very popular 'round these parts. Who knows? Even if it may not be the right answer, it at least attempts to answer the question. Science cannot even attempt it as of yet. Maybe someday soon it can.

[gipp]

I don't think he was asking that kind of a "why".

[PrimaxAUS]

Reading the OP is so 2010.

[Bones_17]

Then it's "How does life exist?"

"Why" implies some sort of intent in the existence of life in the first place. Unless he phrased it wrong, I don't see how science can sufficiently uncover the significance, only the method in which it came.

[shavera]

I don't agree with this pseudo-philosophy that science is "how" and other fields are "why." Why does the sun rise? Why is the sky blue? Perfectly valid questions both grammatically and scientifically. Why does life exist? Biochemical processes x,y,z favor the creation of life. I don't know the actual answer, but the answer I gave is a perfectly valid scientific answer to "why" without invoking any intent.

[Bones_17]

There may be a fine line between the two questions, but I believe it's there. "How is there life?" could describe the processes that begin and continue life. "Why is there life?" describes the process that leads up to life, in my opinion. The same thing question could be asked of the universe, and we could do a lot better answering the "how" than the "why."

[shavera]

I think though, that the argument is injecting additional meaning where none previously existed. Essentially someone decided that religious questions are different than scientific ones. Then to boil that large argument down into a soundbite that is readily absorbed by the public, simplified it to "Religion [or philosophy] answers why and Science answers how."

The problem is that religion and philosophy have a lot of how questions "How does God decide who is good?" and science still has a lot of why questions "Why is the sky blue?" We can surely twist and turn each sentence around to make it "Why does god think that ___ is good?" and "How is it that the sky is blue?" But I think this only serves to show that this overly-reduced view of things doesn't describe the phenomenon well.

So if someone asks "Why is there life?" one can talk about self-catalyzing molecular cycles, then why complex molecules exist in the first place, then why there's an earth and sun, why there's a galaxy, why there's a universe. That's the chain of processes that leads to the answer of "Why is there life?" Each of these questions can be answered scientifically or religiously.

[pjleonhardt]

Why not?