zapatos Posted July 1, 2019 Posted July 1, 2019 2 hours ago, pavelcherepan said: there can be plenty of valid reasons to question abiogenesis. If there once wasn't life and there now is life, what else is there but abiogenesis? 1
pavelcherepan Posted July 1, 2019 Posted July 1, 2019 11 hours ago, zapatos said: If there once wasn't life and there now is life, what else is there but abiogenesis? Taking it in a literal sense - yes, but on the other hand the term 'abiogenesis' currently refers to a mix of several hypotheses on origin of life, neither of which has gives any understanding of what might have happened. It's like dark energy - it's used as an explanation to an observed phenomena, but no one has any clue as to what it actually is, just guesses.
dimreepr Posted July 1, 2019 Posted July 1, 2019 2 minutes ago, pavelcherepan said: Taking it in a literal sense - yes, but on the other hand the term 'abiogenesis' currently refers to a mix of several hypotheses on origin of life, neither of which has gives any understanding of what might have happened. It's like dark energy - it's used as an explanation to an observed phenomena, but no one has any clue as to what it actually is, just guesses. Not really guesses, we do know what it can't be.
pavelcherepan Posted July 1, 2019 Posted July 1, 2019 5 minutes ago, dimreepr said: Not really guesses, we do know what it can't be. Well, fair enough. Maybe a bad analogy, but all analogies are. By the way, I totally forgot to ask a very important question - for the purposes of this discussion what do we define as 'life'? Are viruses 'life'? What about preons? Where is the boundary between life and non-life?
dimreepr Posted July 1, 2019 Posted July 1, 2019 2 minutes ago, pavelcherepan said: Well, fair enough. Maybe a bad analogy, but all analogies are. By the way, I totally forgot to ask a very important question - for the purposes of this discussion what do we define as 'life'? Are viruses 'life'? What about preons? Where is the boundary between life and non-life? Lets not jump down that rabbit hole here, it would be interesting in another thread.
pavelcherepan Posted July 1, 2019 Posted July 1, 2019 4 minutes ago, dimreepr said: Lets not jump down that rabbit hole here, it would be interesting in another thread. But it's really hard to discuss the question of abiogenesis since it really depends on what we define as 'living'. Otherwise the discussion is quite meaningless.
beecee Posted July 1, 2019 Author Posted July 1, 2019 7 hours ago, pavelcherepan said: But it's really hard to discuss the question of abiogenesis since it really depends on what we define as 'living'. Otherwise the discussion is quite meaningless. I'm not that far into biology, and am actually learning as I go. Perhaps viruses are just another step or a biological entity towards actual full blown defined life.
pavelcherepan Posted July 1, 2019 Posted July 1, 2019 1 hour ago, beecee said: I'm not that far into biology, and am actually learning as I go. Perhaps viruses are just another step or a biological entity towards actual full blown defined life. Normally these days viruses are not considered 'living' even though they are based on an extremely complex self-replicating RNA molecule. Preons that I mentioned are even simpler - they are proteins but they work in such a way that when coming into contact with proteins in your body they will modify them to assume the same structure, causing nasty things like mad cow's disease. Simply put, the boundary between life and non-life is not really well defined at all.
CharonY Posted July 1, 2019 Posted July 1, 2019 50 minutes ago, pavelcherepan said: Normally these days viruses are not considered 'living' even though they are based on an extremely complex self-replicating RNA molecule. Preons that I mentioned are even simpler - they are proteins but they work in such a way that when coming into contact with proteins in your body they will modify them to assume the same structure, causing nasty things like mad cow's disease. Simply put, the boundary between life and non-life is not really well defined at all. Nitpicks incoming: Note that not all viruses are RNA viruses. Also, prions are spelled with an "i" and they do not cause misfolding in random proteins, but rather if they are misfolded a certain way, they then can result in conformational changes in other prions, creating a snowball effect of these types of proteins. However, they have no means of replication as the prions to be misfolded have to to be present to begin with. That being said, I agree that we have pretty much a post hoc definition of life, based on shared characteristics we observe in entities that we consider to be life forms. But for for the topic in this thread I think this has very little impact as such. As ultimately we are asking how a specific type of life (the ones on Earth with the shared history pointing to a singular origin).
pavelcherepan Posted July 2, 2019 Posted July 2, 2019 6 hours ago, CharonY said: Note that not all viruses are RNA viruses. Sure. I just specified RNA viruses since according to relatively well accepted RNA-world hypothesis, this is what precluded the more modern DNA-based life. 6 hours ago, CharonY said: Also, prions are spelled with an "i" Ooops! 6 hours ago, CharonY said: That being said, I agree that we have pretty much a post hoc definition of life, based on shared characteristics we observe in entities that we consider to be life forms. But for for the topic in this thread I think this has very little impact as such. As ultimately we are asking how a specific type of life (the ones on Earth with the shared history pointing to a singular origin). Sort of agree. Mostly the discussion is centered around beecee's statement: "certainly we know that at one time there was no life [universally speaking] then there was". The way this is phrased alludes to some relatively sharp boundary between 'living' and 'non-living'. while in fact there seems to have been a progressive transition from one to another.
Eise Posted July 2, 2019 Posted July 2, 2019 17 hours ago, pavelcherepan said: By the way, I totally forgot to ask a very important question - for the purposes of this discussion what do we define as 'life'? Are viruses 'life'? What about preons? Where is the boundary between life and non-life? For abiogenesis I think this is not relevant: without living hosts viruses cannot replicate. So life must have been first. Viruses are more degenerated life. We must not forget that evolution makes 'climbing mount improbable' possible, but it can also lead to simpler life forms.
pavelcherepan Posted July 2, 2019 Posted July 2, 2019 (edited) 39 minutes ago, Eise said: For abiogenesis I think this is not relevant: without living hosts viruses cannot replicate. So life must have been first. Viruses are more degenerated life. We must not forget that evolution makes 'climbing mount improbable' possible, but it can also lead to simpler life forms. What is your view on 'RNA world' hypothesis? If it's correct and self-replicating RNA existed before DNA came to existence, they didn't require living hosts to replicate as there wouldn't have been any. Maybe I was wrong in speaking about viruses, since in this case these RNA would act differently from a modern day virus, which indeed needs a living host to replicate. Edited July 2, 2019 by pavelcherepan
beecee Posted July 2, 2019 Author Posted July 2, 2019 1 hour ago, Eise said: For abiogenesis I think this is not relevant: without living hosts viruses cannot replicate. So life must have been first. Viruses are more degenerated life. We must not forget that evolution makes 'climbing mount improbable' possible, but it can also lead to simpler life forms. Nice point!! Which sort of puts and end to my hypothesis here..... 11 hours ago, beecee said: I'm not that far into biology, and am actually learning as I go. Perhaps viruses are just another step or a biological entity towards actual full blown defined life.
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