Can life begin today as it did 4billion years ago

[calis]

Hello I am new to the field.

Can someon answere, i cannot find the answere in books.

if life 3.8 billion years ago could form in very harsh conditions. then whay cannot it happen again today. whay cannot it have been happening all the time for almost 4 billion years.

i have read that all animals have a cummon ancestor and all plants have a cummon ancestor too, and there also is a cummon ancestor for both plants and animals, and it all leads back to single cell organism.

now if we can trace back a cummon ancestor for all living or growing things on earth, then where are the living things that came later.

Does this mean that in 4 billion years there have been only one spark of life that led to complete diversity of life... and guess what, it happened right next day after Earth stopped being bombarded by asteroids. hmm what a coincidence.

1. WHERE ARE ANIMALS (OR SOMETHING ELSE ALIVE) THAT APEARED AFTER THE EARTH WAS ALLREADY INHABITED?

2. have this aspect been discussed in science world?

3. If we want to know so bad how life on Earth got started, cannot we just observ it starting today?

 

[mgb_phys]

if life 3.8 billion years ago could form in very harsh conditions. then whay cannot it happen again today.

The same type of life can't start again, we have been filling the atmosphere with a highly toxic gas called Oxygen for the last 3Bn years.

i have read that all animals have a cummon ancestor and all plants have a cummon ancestor too, and there also is a cummon ancestor for both plants and animals, and it all leads back to single cell organism.

Correct. But it even goes further than that, there are common ancestors for plants+animals and fungi and all complex celled organisms and for simple celled organisms.

now if we can trace back a cummon ancestor for all living or growing things on earth, then where are the living things that came later.

Like us ?

Generally the problem for entirely new forms of life to appear now is that there is a lot of competition. Anything with any chemical energy (which is pretty much the definition of life in these terms) would instantly be food for some other existing form of life.

 

[calis]

Ok but it is not said that new life forms necesserily have to be food for someone else.

well it started first time when there was no oxigen. life can get through hardship.

I mean advanced life on Earth have been for something like 500 million years. is it really so that for all this time it have been desperatelly trieing to begin everywhere on planet, and consitantly failed for 500 million years by becoming food to existing species?
life can form in a way that it is not eatable (rock-like life for example), or in places or time where are no predators (after great extinction 250 million years ago (siberian traps))

 

[SW VandeCarr]

Hello I am new to the field.

Can someon answere, i cannot find the answere in books.

if life 3.8 billion years ago could form in very harsh conditions. then whay cannot it happen again today. whay cannot it have been happening all the time for almost 4 billion years.

Life will almost certainly "begin" de novo in our time. It will happen in a laboratory somewhere. Life is chemistry and we understand a lot of that chemistry now. We can synthesize proteins and nucleic acids. Getting them to work together in a test tube or Petri dish is the current challenge. To say this is artificially created life is missing the point. Life on Earth (us) will create new life forms from non-living molecules.

 

[calis]

Life will almost certainly "begin" de novo in our time. It will happen in a laboratory somewhere. Life is chemistry and we understand a lot of that chemistry now. We can synthesize proteins and nucleic acids. Getting them to work together in a test tube or Petri dish is the current challenge. To say this is artificially created life is missing the point. Life on Earth (us) will create new life forms from non-living molecules.

the question of curse is not about artificial life creation

 

[SW VandeCarr]

the question of curse is not about artificial life creation

As you said, and have been told by others, the conditions for spontaneous development of life do not appear to exist on Earth today. Moreover, any near-life would almost certainly be eaten before it got very far. However, there's nothing artificial about the kind of life that might come out of a laboratory. It will chemically be life, with self replicating DNA or RNA coding for proteins within a primarily lipid membrane. It will have metabolism and replicate (the basic defining features of life). The only thing that's different is that the first generation will be not be spontaneously generated.

 

[russ_watters]

Ok but it is not said that new life forms necesserily have to be food for someone else.

Why not? Or more to the point: how can the new life defend itself from being eaten?

well it started first time when there was no oxigen. life can get through hardship.

You missed the point: when there was no oxygen, the Earth was more hospitible to the original life. Then that original life polluted the atmosphere and essentially caused its own demise.

I mean advanced life on Earth have been for something like 500 million years. is it really so that for all this time it have been desperatelly trieing to begin everywhere on planet, and consitantly failed for 500 million years by becoming food to existing species?
life can form in a way that it is not eatable (rock-like life for example), or in places or time where are no predators (after great extinction 250 million years ago (siberian traps))

There is good reason to believe that life must be chemically/biolgically compatible with what we have now. Things like the chemical properties of carbon and water appear to be unique and important (and are features of our planet). Rock like life? I saw that on a movie once - it's just fantasy. And there is no such thing as a place with no predators - everywhere on Earth hospitable to life is already covered with it.

 

[calis]

Ok OK.

Even if I think that entirly new life forms that began life after world was inhabited does not neceserally have to be eaten stright away.

(I mean there are so many speceis in world that should not exist because someone should have eaten them well before it even got started ( for example slowmoving, week, small and yet rather dumb, ground animals in sabretooth cat world - austrolapitecs))

but even if all newly appearing life forms are being eaten by existing ones, at least for some time this strange, alien like weird DNA or no DNA life can be found here or there, at least the remains of such life. or other signs that it has existed.

cummon there have been billions of years of time for alternative life to evolve, that does not use our DNA alfabet, but stors information elsehow.

you are saying atmosphere is polluted with deadly poison - oxigen. Is it proved somewhere that new life forms can appear only in oxigenfree world?

 

[russ_watters]

Note that "newly formed life" means something no more complicated than a bacterium. And for the first couple of billion years, it was all bacterium and similar organisms. A small land animal (like a mouse) represents billions of years of evolution. So it wouldn't make sense to think there would be fossils or other remnants of completely different life.

you are saying atmosphere is polluted with deadly poison - oxigen. Is it proved somewhere that new life forms can appear only in oxigenfree world?

No, we don't know that - we only know that there was never the option for life to begin in an oxygen rich world on Earth as the Earth was covered with life before oxygen filled the atmosphere.

 

[mgb_phys]

you are saying atmosphere is polluted with deadly poison - oxigen. Is it proved somewhere that new life forms can appear only in oxigenfree world?

No I was saying that the same chemical path way use by the earliest life on Earth couldn't be used now. Some relatives of the early anaerobic bacteria do still survive, anywhere that smells bad.
It doesn't mean that life can't begin using oxygen, we have recently found life in ocean vents and in deep oil wells that lives on sulphur. Pretty much anywhere there is available chemical energy then something will appear/adapt to use it.

It is easy to imagine alien life that didn't use RNA/DNA (that's one reason to laugh at people that use DNA as the definition of life) what would be interesting is alien life that didn't use some discrete gene-like mechanism for inheritance - that would be interesting.

 

[DavidSnider]

Funny. Now that we know about genes a non-gene like mechanism would be interesting. For the whole of human history before that everybody pretty much assumed it was like mixing chemicals =)

 

[SW VandeCarr]

Funny. Now that we know about genes a non-gene like mechanism would be interesting. For the whole of human history before that everybody pretty much assumed it was like mixing chemicals =)

There are autonomous proteins called prions which can infect animals and humans (Mad Cow disease). As infectious agents, they can be considered quasi-life forms, but they have no nucleic acids. They invade nerve cells and convert normal proteins to abnormal ones. They are unlike viruses in that viruses do have DNA or RNA.

http://www.cdc.gov/od/ohs/biosfty/bmbl4/bmbl4s7d.htm

 

[calis]

Note that "newly formed life" means something no more complicated than a bacterium. And for the first couple of billion years, it was all bacterium and similar organisms. A small land animal (like a mouse) represents billions of years of evolution. So it wouldn't make sense to think there would be fossils or other remnants of completely different life.

Ok but I know that there is no mouse size organism.

I am saying that leftovers from alienlike single cell organisms are not even found. every single cell organism that has EVER lived have ONLY one tipe of DNA. We have found a LOT of extinct single cell organisms but they all use DNA.

Could it be that life that starts olways start with our good old DNA structure.

What if our way of life is the only way of life - that would mean that wherever we go on what ever planet we find life it will look very much like Earth life?

 

[mgb_phys]

every single cell organism that has EVER lived have ONLY one tipe of DNA. We have found a LOT of extinct single cell organisms but they all use DNA.

Anything that didn't use DNA was probably 2nd place in the eat or be-eaten competition. The palealogy evidence for simple cell's chemistry isn't that good, there could easily be none-DNA early life that we haven't found evidence of, or has left no evidence.
Remember we are talking about <3Bn year old life that was little more than a few associated chemicals - we aren't going to find fossils in the normal sense.

 

[SW VandeCarr]

Anything that didn't use DNA was probably 2nd place in the eat or be-eaten competition. The palealogy evidence for simple cell's chemistry isn't that good, there could easily be none-DNA early life that we haven't found evidence of, or has left no evidence.
Remember we are talking about <3Bn year old life that was little more than a few associated chemicals - we aren't going to find fossils in the normal sense.

As infectious agents, prions probably need to be considered life forms (if it's strict dichotomy between life and non-life). They are certainly around NOW and they're very hard to kill. They are the most primitive life forms known.

There are autonomous proteins called prions which can infect animals and humans (Mad Cow disease). As infectious agents, they can be considered quasi-life forms, but they have no nucleic acids. They invade nerve cells and convert normal proteins to abnormal ones. They are unlike viruses in that viruses do have DNA or RNA.

http://www.cdc.gov/od/ohs/biosfty/bmbl4/bmbl4s7d.htm

 

[mgb_phys]

They are the most primitive life forms known.

They are the simplest structure that could be called life (or pseudo life).
I'm not sure that they are necessarily ancient or that that more complex life evolved from them - prions seem to have formed from animal proteins and are found in only a few species which suggests modern,

 

[SW VandeCarr]

They are the simplest structure that could be called life (or pseudo life).
I'm not sure that they are necessarily ancient or that that more complex life evolved from them - prions seem to have formed from animal proteins and are found in only a few species which suggests modern,

You're most likely correct. Nevertheless, they manage to replicate without nucleic acids. It's still not known for certain, but they probably use the host DNA or mRNA in some way which would explain why they are so species specific.

 

[CRGreathouse]

Does this mean that in 4 billion years there have been only one spark of life that led to complete diversity of life...

We don't know. Current evidence points strongly toward that sort of monogenesis. If there were several they would have happened around the same time -- otherwise the ones that were earlier would have a strong enough competitive advantage to simply wipe out the others (as food sources or competitors).

and guess what, it happened right next day after Earth stopped being bombarded by asteroids. hmm what a coincidence.

What day was that? As far as I know we're still being bombarded regularly.

1. WHERE ARE ANIMALS (OR SOMETHING ELSE ALIVE) THAT APEARED AFTER THE EARTH WAS ALLREADY INHABITED?

Don't be silly. Animals are far too complex to develop independently. Even modern bacteria with their many organelles are much more complicated than any spontaneous creation would be.

The trouble is that even if there was an abiogenesis event now (conditions are very different now, but I see no reason this wouldn't happen) the resultant life-form wouldn't be able to survive amongst the broad variety of existing life, which would have billions of years of evolutionary advantage over the new creation.

Now if we could carefully eradicate all life on Earth (including viruses, for those who may not otherwise consider these living) without altering other conditions overly then I'd put my money on seeing abiogenesis -- heck, I think it would be pretty fast, too, maybe less than a million years. But it would probably take hundreds of millions of years before they were even close to modern one-celled organisms in terms of complexity.

(Anyone wishing to pick this apart, feel free!)

 

[philnow]

^ Totally agreed. Well said.

 

[SW VandeCarr]

Now if we could carefully eradicate all life on Earth (including viruses, for those who may not otherwise consider these living) without altering other conditions overly then I'd put my money on seeing abiogenesis -- heck, I think it would be pretty fast, too, maybe less than a million years. But it would probably take hundreds of millions of years before they were even close to modern one-celled organisms in terms of complexity.

(Anyone wishing to pick this apart, feel free!)

I agree with you generally except for this last part quoted above. Why do you think life would begin now, given current conditions are so different now than 3.5-4.0 billion years ago? You are aware that early life was anaerobic and existed under reducing conditions. Oxygen was a product of their metabolism which accumulated in the atmosphere and eventually poisoned most, but not all anaerobic species. It's true that anaerobes survive today, in such environments as the human mouth (under the gum line) and colon. But if you eradicate all the mouths and colons (and biology in general), its not clear where anaerobes might get started today. Either you need to outline a new mechanism for abiogenesis under oxidizing conditions or indicate where and how life might begin on present day Earth in reducing conditions (absent mouths and colons).

http://nitro.biosci.arizona.edu/courses/EEB105/lectures/Origins_of_Life/origins.html

There's also a good article in the source that can't be mentioned.

 

[calis]

Anything that didn't use DNA was probably 2nd place in the eat or be-eaten competition. The palealogy evidence for simple cell's chemistry isn't that good, there could easily be none-DNA early life that we haven't found evidence of, or has left no evidence.
Remember we are talking about <3Bn year old life that was little more than a few associated chemicals - we aren't going to find fossils in the normal sense.

actually I was thinking of not 3 bn years old single cell organisms, I believe we will not find any fossils or any leftovers.

with this topic I tried to say that life just as well shuld have formed recently, let's say couple of millions of years ago. then the fossil record whould not be burried way beneath ground level but sitting right next to some mammouths, then it should be rather easy to find such organism leftovers, stromatolite beginigs for example

 

[BoomBoom]

Could it be that life that starts olways start with our good old DNA structure.

Yes, it could very well be so.


Also, new life could also be starting all the time and never really gets the chance to evolve into anything more complex due to competition with existing life.

I know I always bring this up when this subject is discussed, but Craig Ventor's ocean sequencing project uncovered millions of new genes not found in any other life forms. So who's to say this can't be possible evidence of new life?

Personally, IMO, I find it hard to believe that life was just a one-time freak accident...

 

[Louiswap]

Hi Calis: Earlier mgb mentioned, "The same type of life can't start again, we have been filling the atmosphere with a highly toxic gas called Oxygen for the last 3Bn years": Such comments are arguable.. The Precambrian world was covered with water and dense with water vapor.. Its hard to have water without oxygen being involved somewhere. Blue-green algae are the oldest fossils on Earth (3.5BY - 3.8BY), and they still exist to this day. This primitive life hasn't had problems living now, around abundant oxygen, or in the past with little, or perhaps no oxygen.

The big mystery is why the precursors to these blue-green algae never managed to leave a single trace of their bodies anywhere... 4.5BY ago there's earth, then presto, 3.8BY ago, there's blue-green algae. Every single one of those pre-algae creatures agreed to disappear from the face of the planet and leave not a single trace of their existence. Now that's cooperation.

 

[CRGreathouse]

I agree with you generally except for this last part quoted above. Why do you think life would begin now, given current conditions are so different now than 3.5-4.0 billion years ago?

Because I don't think those conditions were necessary for life. I think life formed as it did because of the environment (there's no advantage to tolerating free oxygen if it's not around). I don't see anything inherently difficult about surviving in an oxygen- (or methane-, or nitrogen-) rich environment, unlike (say) in a high x-ray emission environment.

But I could be convinced otherwise. Why do you think that abiogenesis requires conditions like the early Earth?

 

[CRGreathouse]

The big mystery is why the precursors to these blue-green algae never managed to leave a single trace of their bodies anywhere... 4.5BY ago there's earth, then presto, 3.8BY ago, there's blue-green algae. Every single one of those pre-algae creatures agreed to disappear from the face of the planet and leave not a single trace of their existence. Now that's cooperation.

Most bacteria can't leave fossils. Cyanobacteria (your blue-green algae) have thick enough cell walls that they can sometimes leave fossils. The easiest explanation would be that the precursors to cyanobacteria, like most bacteria, lacked these thick cell walls.

 

[MATLABdude]

Because I don't think those conditions were necessary for life. I think life formed as it did because of the environment (there's no advantage to tolerating free oxygen if it's not around). I don't see anything inherently difficult about surviving in an oxygen- (or methane-, or nitrogen-) rich environment, unlike (say) in a high x-ray emission environment.

But I could be convinced otherwise. Why do you think that abiogenesis requires conditions like the early Earth?

Miller-Urey and Miller-Urey-like experiments (which managed to produce nucleic and amino acids) have always been performed in a reducing atmosphere. Sure, that was to try to replicate the early conditions on our earth, and with an end goal of producing the biochemistry we have today, but are there any oxidizing equivalents?

 

[Louiswap]

Most bacteria can't leave fossils. Cyanobacteria (your blue-green algae) have thick enough cell walls that they can sometimes leave fossils. The easiest explanation would be that the precursors to cyanobacteria, like most bacteria, lacked these thick cell walls.

Can't leave fossils.? The scientists studying that Mars meteorite are going to be disappointed to hear you say that.

However, the blue-green alga has over a hundred different proteins that make up just the cell wall alone. That's a lot, I admit, but to say that evolution jumped from an extremely simple something to this cyanophyte is quite a step. Evolutionists usually try to insert an evolutionary tree between quantum steps. Perhaps, say only 95 proteins. Even earlier, perhaps only 85. Where's the fossil remains.?

"Sometimes leave fossils".? Please know that these specific fossils are on every continent. I've got a driveway lined with these same fossils (I gathered them from the Missoula, Montana, area).

 

[SW VandeCarr]

But I could be convinced otherwise. Why do you think that abiogenesis requires conditions like the early Earth?

,

That's not the point. You can posit any "what-if" scenario you want. You're saying what if all life, including bacteria disappeared, then...? It's a completely unscientific proposition.

There's good reason to believe that life began sometime between 3.5-4.0 Gya and that there was some form of pre-biotic chemistry perhaps up to 4.2 Gya, following the final bombardment. Since the first known bacteria were anaerobic, it's safe to assume that anaerobic conditions existed. No? Since anaerobic bacteria produce free O_2 as a waste product, it's probably likely that the demise of most anaerobic species was to due to O_2 poisoning with the exception of a few organisms that adapted (perhaps even just one).

Yes, you could say that maybe aerobic bacteria came about by a new abiogenesis rather than by natural selection. You could say they all came from extraterrestrial sources like James Watson apparently believes. You can say almost anything you want, but science is based on evidence. The current evidence points to life beginning in a mild reducing environment with very little free O_2 and natural selection eventually leading to aerobic life.

 

[CRGreathouse]

That's not the point. You can posit any "what-if" scenario you want. You're saying what if all life, including bacteria disappeared, then...? It's a completely unscientific proposition.

Let's hope that propositions stays in the non-science section. It's experimentally verifiable, but that would be B-A-D.

There's good reason to believe that life began sometime between 3.5-4.0 Gya and that there was some form of pre-biotic chemistry perhaps up to 4.2 Gya, following the final bombardment. Since the first known bacteria were anaerobic, it's safe to assume that anaerobic conditions existed. No? Since anaerobic bacteria produce free O_2 as a waste product, it's probably likely that the demise of most anaerobic species was to due to O_2 poisoning with the exception of a few organisms that adapted (perhaps even just one).

We're in complete agreement here.

I don't care to speculate about the fraction of organisms that adapted vs. those that died out; for one I'm not even sure how that would be measured in principle. You don't happen to have any numbers or information on that, do you?

Yes, you could say that maybe aerobic bacteria came about by a new abiogenesis rather than by natural selection.

But I'm not saying that at all! If I gave that impression, I'm sorry to have mislead you; if your point was some kind of analogy, I missed it entirely. (Sorry.)

 

[CRGreathouse]

Can't leave fossils.? The scientists studying that Mars meteorite are going to be disappointed to hear you say that.

Why? They expect only that some would, not that all or even most would. And they'd be hoping for some fairly advanced bugs, which would be able to produce such structures as cell walls and various organelles.

However, the blue-green alga has over a hundred different proteins that make up just the cell wall alone. That's a lot, I admit, but to say that evolution jumped from an extremely simple something to this cyanophyte is quite a step.

But I didn't say or even suggest that they did.

Evolutionists usually try to insert an evolutionary tree between quantum steps.

There are of course different schools of thought here (the PE crowd, for example), but I'll not go into that. I'm more of a gradualist anyway.

Perhaps, say only 95 proteins. Even earlier, perhaps only 85. Where's the fossil remains.?

Simpler bacteria with thinner walls, plus being older and hence more worn. I'd think most wouldn't have lasted and the balance would be difficult to tell from modern ones. How can we tell the # of proteins just from a fossil? We're mostly looking at gross anatomy AFAIK.

"Sometimes leave fossils".? Please know that these specific fossils are on every continent. I've got a driveway lined with these same fossils (I gathered them from the Missoula, Montana, area).

This fits with my understanding very well. Say 10^10 generations of bacteria with maybe 10^27 (now) to ? (then) bacteria per generation... what fraction would you expect to leave fossils? To put it another way, what fraction of Earth's mass do you think is bacterial fossils?

 

[SW VandeCarr]

Let's hope that propositions stays in the non-science section. It's experimentally verifiable, but that would be B-A-D.

OK, your "hypothesis". What do mean experimentally verifiable? Say you completely sterilized some marine/tide pool environment (and were able to keep it sterile somehow). You say aerobic life might start de novo in a million years. That's an instant in geologic time, but a bit long for a government grant. I don't think we've seen a proton decay yet, but that experiment is a microsecond affair compared to waiting around for new aerobic life to start.

I don't care to speculate about the fraction of organisms that adapted vs. those that died out; for one I'm not even sure how that would be measured in principle. You don't happen to have any numbers or information on that, do you?

Of course not. I just said that a mutation in just one individual might have been sufficient to get an aerobic species going. Obviously some anaerobic species survived since they're still around, producing nasty purulent infections (probably revenge against us aerobes).

But I'm not saying that at all! If I gave that impression, I'm sorry to have mislead you; if your point was some kind of analogy, I missed it entirely. (Sorry.)

(RE: Early Precambrian aerobic abiogenesis) I'm just saying that if (natural) aerobic abiogenesis were possible, it most likely would have happened then (as the anaerobes were dying off creating locally sterile environments) as opposed to now.

 

[Count Iblis]

The building blocks of life likely evolved in space:

http://www.astrochem.org/PDF/Bernsteinetal2002.pdf

 

[SW VandeCarr]

The building blocks of life likely evolved in space:

http://www.astrochem.org/PDF/Bernsteinetal2002.pdf

Yes. I think it's generally accepted that organic compounds exist in space. These would include some amino acids and, I believe, purines and pyrimidines.