How did the first living thing on earth come to life?

[lilithu]

There are several theories and possibilities. The one i was taught as most likely was the primordial soup origin theory.
For life as we know it we need three basic constituents; amino acids, a coding chemical (DNA or RNA) and a lipid bilayer.
Amino acids form readily under lab based recreations of what the early Earth would have been like. And even if they didn't, it wouldn't be a problem because amino acids rain to Earth in great quantities within meteorites every day, and 3.5 billion years ago there would have been many million times the number meteorite collisions we have today.

Lipid bilayers are what constitute the membranes of all living cells. They are relatively simple in structure and again coacervates (spheres of lipid membranes) have been formed under lab conditions.

DNA and RNA are the complicated part, although its reasonably safe to say the use of these coding molecules occured after a very basic form of cell, composed of only protein and lipids, began to evolve.
Proteinoid microspheres are by far the most compelling evidence for a pre-nucleic, protein-only cell form. These microspheres have been produced under laboratory conditions, they show some membranous selectivity, they grow larger with consumption of surrounding amino acids and they exhibit binary fission, just like cells we recognise as living today.

I have no idea how these cell precursors began using nucleic acids as informational storage. However there are theories;
http://www.nature.com/embor/journal/v1/n3/full/embor574.html

This article is a good outline, if a little presumptive for my tastes.

Hi Halcyon,

Actually, I can see how DNA and RNA came to be. RNA is relatively simple in structure and it's not hard to see how DNA could have developed from RNA. I can see how proteins might arise thru a "natural selection" type process where useful protein structures and the nucleic acid sequence that encodes it becomes fixed while non-useful structures are not. And as you said the lipid bilayer is easy. What I can't wrap my mind around is the numerous and interdependant biochemical reactions that go on in a cell in order for it to function. I think there are like over twenty reactions that are absolutely essential for cell function. How did they all come together in one place at one time? I can envision how the components necessary for one or two or even three reactions could have been in close enough proximity that they got sequestered together in a proto-cytoplasmic soup when a lipid bilayer sealed into a sphere. But I can't grasp how that could happen for over twenty reactions. And since they are all essential reactions, it seems to me that it can't be the case that it started with a smaller number that created a simpler proto-cell that then built up from there.

Just to be clear, I'm not arguing in favor of creationism. I'm just saying that I don't get it.

 

[lilithu]

Actually, evolution proves there is no need for a creator god, or any other god for that matter, the multiverse is ruled by chaos.

Evolution suggests that there is no need for a creator god. It does not logically follow from that that the multiverse is ruled by chaos.

 

[logician]

Considering the many, varied and extreme conditions life can exist under on the earth now, it is not so much of a jump to think life could have originated in the primordial seas as many amino acid combinations built up over billions of years.

 

[logician]

Evolution suggests that there is no need for a creator god. It does not logically follow from that that the multiverse is ruled by chaos.

The multiverse is ruled by chaos is an observation, not a logical conclusion from evolution.

 

[lunamoth]

Hi Halcyon,

Actually, I can see how DNA and RNA came to be. RNA is relatively simple in structure and it's not hard to see how DNA could have developed from RNA. I can see how proteins might arise thru a "natural selection" type process where useful protein structures and the nucleic acid sequence that encodes it becomes fixed while non-useful structures are not. And as you said the lipid bilayer is easy. What I can't wrap my mind around is the numerous and interdependant biochemical reactions that go on in a cell in order for it to function. I think there are like over twenty reactions that are absolutely essential for cell function. How did they all come together in one place at one time? I can envision how the components necessary for one or two or even three reactions could have been in close enough proximity that they got sequestered together in a proto-cytoplasmic soup when a lipid bilayer sealed into a sphere. But I can't grasp how that could happen for over twenty reactions. And since they are all essential reactions, it seems to me that it can't be the case that it started with a smaller number that created a simpler proto-cell that then built up from there.

Just to be clear, I'm not arguing in favor of creationism. I'm just saying that I don't get it.

I don't think it would be a matter of the 20 or functions having to arise separate from each other and then somehow coming to gether in a micell. The proto-cells could not have all the kinds of functions we associate with the cells we know today, they would merely have to have the ability to replicate the information molecule and then somehow split, which could perhaps occur just based upon the physical properties of the cell (two small blobs are more stable than one large blob).

We know that simple RNA molecules have enzymatic activities, thus you have an organic molecule that can replicate itself and is still quite simple. How it became advanatgeous to have a lipid (OK RER, phospholipid ) bilayer is what mystifies me. The last time I looked at abiogensis models it was postulated that the membrane bilayer was a rather early development. So, say you've got a small self-replicating organic molecule like RNA. There's got to be a large abundance of the precurser molecules (and a ribonucleotide is far from a simple molecule) available in the environment, and so we'll assume that this is the case. The advantage of having a lipid bilayer might be so that the molecule can modifiy its microenvoronment, esp pH for example, and suppsedly if you start to have more than one kind of complex organic molecule involved it provides a scaffold for keeping those molecules in close proximity to each other. But...

If we are talking about transporting the precursor molecules from the environment across the lipid bilayer to the replication machinery of the proto-cell, you are already talking about having the presence of some kind of specialized transport molecule embedded in the lipid bilayer. Nucleotides are not just going to freely diffuse across the membrane by themselves, at least not at a rate that would be fast enough to keep up with the replication process. But, if you've got an information molecule that is already complicated enough to synthesize transport proteins...then you are getting to a system that requires a rather large number of biochemical processes already put together on your information molecule...and you do hit the problem that Lilithu points out. But this is no reason to invoke Goddidit.

I actually think that the lipid membrane came much later, after quite complex systems of RNAs and proteins were already working together and hanging together by other kinds of molecular interactions, not being contained in a membrane. Rather further down the road I can imagine lipid membranes being used by these nucleic acid-protein complexes, but not surrounding them (yet). Instead I would bet that the first membranes might be little bubbles that adhere to the complex with parts of the proteins embedded into the lipid bilayer, so that the membrane is being used to organize the proteins like scaffolding, rather than as a protective surrounding. Eventually some of the membrane-bound proteins would take on the functions of 'recruiting' precursor molecules, the function of transport, and after that it would be possible for a lipid bilayer to surround the entire complex.

No, I've not published this. To my knowledge it's original.: hamster :

 

[carlosox]

Hindus believe that evolution is a fact but that man was a special creation of the Maker. In South Korea school children are now taught that man was created by aliens who arrived on earth in UFOs??!!
Regards

 

[Halcyon]

Just to be clear, I'm not arguing in favor of creationism. I'm just saying that I don't get it.

I can see how most of it would happen, and i agree with luna that it probably occurred in stages with proto-cells lacking many of the components we deem vital today, but still being functional.

What i don't understand is how protein synthesis became linked with RNA/DNA coding. I mean we have AAs forming simple proteins in the right lab conditions, but how did the RNA get involved?
I can only think it developed backwards. Somehow tRNA-like molecules linked with AAs first, then its fairly simple to see how those tRNAs could line up along an mRNA molecule, but the chances of getting an RNA molecule of required length and in a workable order is mind-boggling.
Perhaps DNA developed separately, but then how do all the necessary synthesis enzymes come to be? IF RNA was first, it must have needed a reverse transcriptase of some sort to produce DNA.
My head hurts.

 

[Super Universe]

All these scientific explanations of what makes up a basic organism still do not answer the original question, how did the first living thing on earth come to life?

DNA, RNA, amino acids, lipid bilayers are not life, they are chemicals. Lightning does not give life. A single cell is not life, it has life, life that can join with it and leave it as well. Scientists can join together all these chemicals in their proper form but it will not come to life.

No human has the power of creation, only God can do that. What humans do is separate things, combine them, change them, but never actually create anything at all.

To simply answer the question, life was brought here by the angels. The earth is just one of a trillion life experiments in the material universe, only it is a bit different in that many types of life (avian, reptilian, humanoid, fish, insect) were intended to evolve here instead of just one.

We are not an accident. Life does not/cannot happen by accident.

The next question should be this, how did sentience first evolve in humans?

And the universe is not ruled by chaos, there are rules, there is organization. Do you really think it created and organized itself?

 

[Ðanisty]

No human has the power of creation, only God can do that. What humans do is separate things, combine them, change them, but never actually create anything at all.

Because we have not done something does not mean that we cannot do something.

To simply answer the question, life was brought here by the angels. The earth is just one of a trillion life experiments in the material universe, only it is a bit different in that many types of life (avian, reptilian, humanoid, fish, insect) were intended to evolve here instead of just one.

And how exactly do you know what life formed on other planets? How do you know that no other planets have multiple kinds of life forms? There is no way for you to know that. We haven't been there yet. I certainly agree that life exists elsewhere, but nobody knows the details.

We are not an accident. Life does not/cannot happen by accident.

My brother was an accident.

 

[Super Universe]

I also did not say that no other planets have multiple kinds of life but perhaps I didn't explain this well enough.

Most life experiments do not have nearly as much life variation as the earth. Perhaps plants, fish, and reptiles. Maybe plants, fish, and insects but never all six.

The avian, reptilian, humanoid, fish, insectoid, and plant forms are each dominant capable lifeforms in their own respect. This means that each of them is capable of evolving to the point that it becomes sentient. When one form evolves enough and is given sentience the other forms cannot then become sentient on that planet.

Humanoids are the dominant lifeform on the earth.

There is no way for me to know this? Ask yourself this, how did Einstein figure out that space is time?

 

[YmirGF]

Me? I go with the primordial soup mix myself. I certainly don't understand the science of it, but get the drift, at least. The scientific answer if a bit more reasonable than what religious folks would have us believe, especially the "new Earther" adepts.

 

[Halcyon]

Humanoids are the dominant lifeform on the earth.

Surely you mean mammals?

Most life experiments do not have nearly as much life variation as the earth. Perhaps plants, fish, and reptiles. Maybe plants, fish, and insects but never all six.

The avian, reptilian, humanoid, fish, insectoid, and plant forms are each dominant capable lifeforms in their own respect.

What happened to fungi, annelids, crustaceans, molluscs and amphibians to mention a few? Don't they get to be dominant?

 

[lunamoth]

I can see how most of it would happen, and i agree with luna that it probably occurred in stages with proto-cells lacking many of the components we deem vital today, but still being functional.

What i don't understand is how protein synthesis became linked with RNA/DNA coding. I mean we have AAs forming simple proteins in the right lab conditions, but how did the RNA get involved?
I can only think it developed backwards. Somehow tRNA-like molecules linked with AAs first, then its fairly simple to see how those tRNAs could line up along an mRNA molecule, but the chances of getting an RNA molecule of required length and in a workable order is mind-boggling.
Perhaps DNA developed separately, but then how do all the necessary synthesis enzymes come to be? IF RNA was first, it must have needed a reverse transcriptase of some sort to produce DNA.
My head hurts.

That problem blows me away too Hal. It seems impossible that functional proteins and a functional and encoding nucleic acid mechanism would develop independently and then somehow come together they way they do. One must be based upon the other but I can't fathom how this could happen.

Compared to this particular question, things like how the eye developed seem pretty easy to postulate.

Have you heard any good theories?

 

[Super Universe]

You might be correct in that mammals (human terminology) all have received the gift of sentience.

When the genetic engineers plan for a new life experiment there is no desire for an intelligent humanoid species or an intelligent bird species or reptilian or whatever to evolve. There is only the desire for intelligence to evolve.

The class divisions they use are based on heat/cold tolerances, breathing abilities, and salt water availability to the life form. Most of the time they choose what best fits the planetary body's climate but 10% of their experiments are permitted to expand, test, push the genetic limits. The earth is one of those 10% experiments.

The engineers could care less what specific (human defined) class of life evolves to the point of becoming aware.

Only humans classify things to such a degree. We even think there are actually races within our race and use something genetically insignificant as skin color to define them.

 

[Halcyon]

That problem blows me away too Hal. It seems impossible that functional proteins and a functional and encoding nucleic acid mechanism would develop independently and then somehow come together they way they do. One must be based upon the other but I can't fathom how this could happen.

Compared to this particular question, things like how the eye developed seem pretty easy to postulate.

Have you heard any good theories?

Unfortunately not, i don't think i've heard of one theory, nevermind a good one. It think this has everybody stumped at the moment.

You might be correct in that mammals (human terminology) all have received the gift of sentience.

When the genetic engineers plan for a new life experiment there is no desire for an intelligent humanoid species or an intelligent bird species or reptilian or whatever to evolve. There is only the desire for intelligence to evolve.

You mean sapience? Sentience just means you have senses, pretty much all life is sentient. And no, most mammals are not sapient.

See, i think you're confusing the term humanoid. Humanoid just denotes a being in the shape of a human, you could have a mammalian humanoid (like us) or you could have an avian, amphibian or reptilian humanoid.

The class divisions they use are based on heat/cold tolerances, breathing abilities, and salt water availability to the life form. Most of the time they choose what best fits the planetary body's climate but 10% of their experiments are permitted to expand, test, push the genetic limits. The earth is one of those 10% experiments.

The engineers could care less what specific (human defined) class of life evolves to the point of becoming aware.

Only humans classify things to such a degree. We even think there are actually races within our race and use something genetically insignificant as skin color to define them.

There are significant differences between races, from bone structure to blood types. It seems strange that a highly intelligent alien race would go into less depth with their taxonomy than we do???

 

[YmirGF]

There are significant differences between races, from bone structure to blood types. It seems strange that a highly intelligent alien race would go into less depth with their taxonomy than we do???

I'm half expecting him to go on about "precious bodily fluids" at some point. :flirt:

 

[lilithu]

A single cell is not life, it has life, life that can join with it and leave it as well. Scientists can join together all these chemicals in their proper form but it will not come to life.

Define "life."

 

[pete29]

why does it matter

 

[Super Universe]

All life is sentient? How sentient is a plant? A virus? What is it aware of?

Significant differences between races? What blood type belongs only to caucasions or African Americans? None.

The amount of difference between one individual of any race and any other individual of that same race is just as significant. There is only one race, the human race.

What alien race are you talking about? The genetic engineers who plan and conduct life experiments are not aliens, they are angels. If you wish to consider them aliens then God is also an alien and so is all life on this planet including us.

My definition of life is this: possessing some degree of spirit.

 

[logician]

No human has the power of creation, only God can do that. What humans do is separate things, combine them, change them, but never actually create anything at all.

Who created god? YOu say life cannot be created w/o a god, yet a supernatural entity sprang from nothingness, a contradiction.

The multiverse needs no god.