Hello to the LoR, I just wanted to ask something concerning common ancestry, if anyone could shed some more light on the issue that would be great. All organisms are descendant from a common ancestry or gene pool, and they evolved from a prokaryote organism right? My question is where did that prokaryote organism come from?
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Question about ToE
- Thread starter Azaqale
- Start date
australopithecus
Active Member
ToE doesn't deal with origins, it deals with variation and deviation of species once life existed. You'd be better off looking into the various hypotheses in the field of abiogenesis.
And welcome to the forum
And welcome to the forum
Excellent question. In short, I dunno.
Ok, having gotten the "I dunno" answer out of the way, we look at plausible hypothesis of abiogenesis. What you're looking for really is the first replicator, something that could replicate itself with a decent degree of fidelity so that it's descendents inherited it's characteristics. It's pretty hard to even define the barrior between life and non-life in such early times other than as an organism (for want of a better word) with the ability to replicate.
Ok, having gotten the "I dunno" answer out of the way, we look at plausible hypothesis of abiogenesis. What you're looking for really is the first replicator, something that could replicate itself with a decent degree of fidelity so that it's descendents inherited it's characteristics. It's pretty hard to even define the barrior between life and non-life in such early times other than as an organism (for want of a better word) with the ability to replicate.
DutchLiam84
New Member
But...and I can stress this enough...when the word "evolved" is used to describe the change over time of a person, the universe or indeed the first self replicating cell; evolved is used as the colloquial term. The wording might confuse you but is has nothing to do with the Theory of Evolution.
Also, keep in mind that the answer "we don't know" is more intellectually honest than any answer.
E.g.: When you ask 2 children where babies come from....1 says "I don't know" and the other says "Storks bring them". Even though the storks answer might be more satisfactory, the first kids answer is more honest.
p.s. Welcome to the forum!
Also, keep in mind that the answer "we don't know" is more intellectually honest than any answer.
E.g.: When you ask 2 children where babies come from....1 says "I don't know" and the other says "Storks bring them". Even though the storks answer might be more satisfactory, the first kids answer is more honest.
p.s. Welcome to the forum!
Hello there, Azaqale! First and foremost, welcome to the forums! Now, onto your question ...
As everyone else has been prudent to point out, the theories of Evolutionary Science and Abiogenesis are wholly separate fields in biology, and one is a biological theory, while the other , Abiogenesis , has more to do with some nifty and fascinating , as evolution is , hypotheses surrounding pre-biotic chemistry, e.g. the RNA World Hypothesis and so forth, which posits that ribonucleic life was a precursor to what could be termed "deroxyribonuclic life" ... i.e. hence DNA. Of course, if this is true, or if this is not true, is all the more complicated, and the nefarious little details of how one thing lead to another, etc, etc. But in all cases, it is necessary to have a certain degree of knowledge on the chemical and biophysical processes that define life as it exists presently, for example sugar and lipid chemistry, at least for the more complex fields of research, which I of course have rather strong interests in. All we can truly say at present is that there must have been an approximately 500 million year period from the existence of inorganic chemistry in the early days of the Earth, to the arrival of RNA, and ultimately DNA, which obviously later culminated in another equally complex sequence of events that may have allowed the circumstances to arise in which the first cells could appear, and it's also more or less known as a certainty among biologists that the cells on the early earth , e.g. the first cells to ever exist , likely had highly simplified chemical workings in comparison to "modern" unicellular life, baring in mind that all life was unicellular at one point from 3-1 billion years ago or so. This also means that they might not have been "alive" in the sense that we might know "life", even for bacteria, but that's another debate altogether.
"Prokaryotes" are , almost universally single-celled , organisms that lack a nucleus, which would include e.g. bacterium and alike. As I said, life on early-earth was far, far simpler than what we would even call "cells" now, but still. We evolved from prokaryotic organisms living in that era, yes, as did all other taxonomic groupings, e.g. eukaryotes, which are organisms that do have nucleically based cells, and membrane-organs, etc. We are in this group, though we wouldn't normally think to call ourselves them, as is the rest of the animal kingdom... but ALL life didn't necessarily make this transition, and as I said before; there are still Prokaryote organisms living on this planet today, just as there are Eukaryote organisms on this planet today, and apparently there is some speculation as to the kinds of environments that such creatures could be capable of living in. We already know of a wide group including some bacterial and viral species, called "extremophiles", which are organisms that can withstand the most abhorrent, at least by most of life's standards, conditions. It is also quite possible that a number of prokaryotic organisms of the kind you describe could possibly live in the vacuum of space, which sheds a lot of light , at least from all I know , on the development of higher life forms on the early earth, especially as the atmosphere and temperature fluctuated, and gradually cooled. Perhaps some of the prokaryote-cells were capable of surviving in the pools around the highly volcanic areas of the Earth, of which there was a lot more of billions of years ago. This would draw some sort of similarity between them and the so-called "Extremophile" life forms of the present day ...
OK. So, the origin of cells:
All of the life forms in Earth's biosphere are made up of cells, and those cells are capable of self-replicating, at both micro- and macro- scales, e.g. unicellular and multicellular life, etc. But it is of course by no means impossible for these forms to have been produced by a naturalistic sequence of events, for example- evolution is one of those mechanisms, albeit the origin of life is somewhat more tricky, since it's difficult to conclude with any sort of precision events that occurred as long as 2+ billion years ago. But starting with the period before the origin of cells, e.g. pre-biological chemistry, it's quite straightforward according to most of the current hypotheses on this matter. The atmosphere of the Earth 3.5 or so billion years ago was very humid, and the temperature of the planet (average) was far higher than it is today ... plus the Sun was about ≈ 37 % cooler than it is at present, though I doubt that played a significant role. But the airborne gases included HCN (Hydrogen Cyanide), CH[sub]4[/sub] (Methane), Hydrogen, and also NH[sub]3[/sub] (Ammonia) and even some O[sub]2[/sub] (oxygen)(!). It's been proven that HCN and NH[sub]3[/sub], when left in a preformed solution of other chemicals, they seem to merge and produce Adenine, which incidentally is one of the nucleotide bases of DNA. But it's still not a complete nucleotide at this point. In order for that, it requires a group of sugars to be administered to it, e.g. Ribose and phosphates, etc. The transition from nucleotides to polynucleotides is equally, fairly simple. Some of the polynucleotide chains, such as ribonucleic acid(s); have chemical properties that enable them to "copy" themselves, a.k.a. self-replicate, and this was of course a precursor to higher life, and (multi)cellular life ...
During the millions of years that RNA chains were replicating themselves, and passing on their successful traits to their "offspring" , it would be worth noting at this point that the process of natural selection probably existed before the first protocells , the other chemicals in the environment that the RNA is sustaining itself in begin to have an effect on their development and evolution. E.g. lipids , note the phosphur-lipid biolayers of organic biochemistry , since they have a natural propensity to attract other lipids, would form primitive cell-membranes around the RNA strands that had been developing. Those strands of RNA were then protected within the micellঠmembranes formed by the lipids, and could therefore reproduce and replicate with increasing successfulness. And, there, effectively ... Voilà ! The first ribonucleic, prokaryotic cells. Also worth remembering: as I said, these cells are still highly primitive compared to modern cells, due to change through biological evolution. But to treat abiogenesis as though it were part of evolutionary processes is still wrong, despite what you may hear from some. Now, eventually, after hundreds of millions of years, the first DNA molecules were formed in the "double-helix" structure that we are oh-so familiar with. E.g. the formation of the first polypeptides from amino-acids on the early earth. We do not yet have a comprehensive understanding of this process, but as far as we are aware, after about another 400-500 million years of constant change, those molecules had replicated to become the first deroxyribonucleic-prokaryote cells, from which we know the rest of life to have diversified from, but it is important to remember that a comprehensive answer to this problem does not yet exist. With any luck, it will be soon, and I would put my trust in the research done by modern geneticists and biochemists.
So that more or less sums it up I guess. I hope this was at least in some way helpful.
Now, onto your question ... i can only assume that "ToE" stands for "theory of evolution". So then,Azaqale said:
As everyone else has been prudent to point out, the theories of Evolutionary Science and Abiogenesis are wholly separate fields in biology, and one is a biological theory, while the other , Abiogenesis , has more to do with some nifty and fascinating , as evolution is , hypotheses surrounding pre-biotic chemistry, e.g. the RNA World Hypothesis and so forth, which posits that ribonucleic life was a precursor to what could be termed "deroxyribonuclic life" ... i.e. hence DNA. Of course, if this is true, or if this is not true, is all the more complicated, and the nefarious little details of how one thing lead to another, etc, etc. But in all cases, it is necessary to have a certain degree of knowledge on the chemical and biophysical processes that define life as it exists presently, for example sugar and lipid chemistry, at least for the more complex fields of research, which I of course have rather strong interests in. All we can truly say at present is that there must have been an approximately 500 million year period from the existence of inorganic chemistry in the early days of the Earth, to the arrival of RNA, and ultimately DNA, which obviously later culminated in another equally complex sequence of events that may have allowed the circumstances to arise in which the first cells could appear, and it's also more or less known as a certainty among biologists that the cells on the early earth , e.g. the first cells to ever exist , likely had highly simplified chemical workings in comparison to "modern" unicellular life, baring in mind that all life was unicellular at one point from 3-1 billion years ago or so. This also means that they might not have been "alive" in the sense that we might know "life", even for bacteria, but that's another debate altogether.
"Prokaryotes" are , almost universally single-celled , organisms that lack a nucleus, which would include e.g. bacterium and alike. As I said, life on early-earth was far, far simpler than what we would even call "cells" now, but still. We evolved from prokaryotic organisms living in that era, yes, as did all other taxonomic groupings, e.g. eukaryotes, which are organisms that do have nucleically based cells, and membrane-organs, etc. We are in this group, though we wouldn't normally think to call ourselves them, as is the rest of the animal kingdom... but ALL life didn't necessarily make this transition, and as I said before; there are still Prokaryote organisms living on this planet today, just as there are Eukaryote organisms on this planet today, and apparently there is some speculation as to the kinds of environments that such creatures could be capable of living in. We already know of a wide group including some bacterial and viral species, called "extremophiles", which are organisms that can withstand the most abhorrent, at least by most of life's standards, conditions. It is also quite possible that a number of prokaryotic organisms of the kind you describe could possibly live in the vacuum of space, which sheds a lot of light , at least from all I know , on the development of higher life forms on the early earth, especially as the atmosphere and temperature fluctuated, and gradually cooled. Perhaps some of the prokaryote-cells were capable of surviving in the pools around the highly volcanic areas of the Earth, of which there was a lot more of billions of years ago. This would draw some sort of similarity between them and the so-called "Extremophile" life forms of the present day ...
OK. So, the origin of cells:
All of the life forms in Earth's biosphere are made up of cells, and those cells are capable of self-replicating, at both micro- and macro- scales, e.g. unicellular and multicellular life, etc. But it is of course by no means impossible for these forms to have been produced by a naturalistic sequence of events, for example- evolution is one of those mechanisms, albeit the origin of life is somewhat more tricky, since it's difficult to conclude with any sort of precision events that occurred as long as 2+ billion years ago. But starting with the period before the origin of cells, e.g. pre-biological chemistry, it's quite straightforward according to most of the current hypotheses on this matter. The atmosphere of the Earth 3.5 or so billion years ago was very humid, and the temperature of the planet (average) was far higher than it is today ... plus the Sun was about ≈ 37 % cooler than it is at present, though I doubt that played a significant role. But the airborne gases included HCN (Hydrogen Cyanide), CH[sub]4[/sub] (Methane), Hydrogen, and also NH[sub]3[/sub] (Ammonia) and even some O[sub]2[/sub] (oxygen)(!). It's been proven that HCN and NH[sub]3[/sub], when left in a preformed solution of other chemicals, they seem to merge and produce Adenine, which incidentally is one of the nucleotide bases of DNA. But it's still not a complete nucleotide at this point. In order for that, it requires a group of sugars to be administered to it, e.g. Ribose and phosphates, etc. The transition from nucleotides to polynucleotides is equally, fairly simple. Some of the polynucleotide chains, such as ribonucleic acid(s); have chemical properties that enable them to "copy" themselves, a.k.a. self-replicate, and this was of course a precursor to higher life, and (multi)cellular life ...
During the millions of years that RNA chains were replicating themselves, and passing on their successful traits to their "offspring" , it would be worth noting at this point that the process of natural selection probably existed before the first protocells , the other chemicals in the environment that the RNA is sustaining itself in begin to have an effect on their development and evolution. E.g. lipids , note the phosphur-lipid biolayers of organic biochemistry , since they have a natural propensity to attract other lipids, would form primitive cell-membranes around the RNA strands that had been developing. Those strands of RNA were then protected within the micellঠmembranes formed by the lipids, and could therefore reproduce and replicate with increasing successfulness. And, there, effectively ... Voilà ! The first ribonucleic, prokaryotic cells. Also worth remembering: as I said, these cells are still highly primitive compared to modern cells, due to change through biological evolution. But to treat abiogenesis as though it were part of evolutionary processes is still wrong, despite what you may hear from some. Now, eventually, after hundreds of millions of years, the first DNA molecules were formed in the "double-helix" structure that we are oh-so familiar with. E.g. the formation of the first polypeptides from amino-acids on the early earth. We do not yet have a comprehensive understanding of this process, but as far as we are aware, after about another 400-500 million years of constant change, those molecules had replicated to become the first deroxyribonucleic-prokaryote cells, from which we know the rest of life to have diversified from, but it is important to remember that a comprehensive answer to this problem does not yet exist. With any luck, it will be soon, and I would put my trust in the research done by modern geneticists and biochemists.
So that more or less sums it up I guess. I hope this was at least in some way helpful.