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Thread: How life started: what do you think?

  1. #1 How life started: what do you think? 
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    As you know, a few billion years after the big bang, earth formed. Note: there were no organic molecules at that period in time. However, Alexander Oparin hypothesized that organic molecules could have arisen from non-organic molecules. Miller proved this, by putting water, some minerals that could have been found at that time, and the atmosphere that was found at that time into a jar, circulated it for weeks, and at a certain point in the circulation, he created an electrical discharge, similar to the huge amounts of energy that was being released at that time. He proved that organic molecules could come from non organic substances. He created the building blocks of matter: some amino acids, and the most important thing: nucleotides, which are the building blocks of DNA, which are pentose sugars, but you can look that up on your own. Anyways, the biggest problem with Miller's experiment was that even though the building blocks of living things came up, there was not any living material; the parts didn't come together. Later, another scientist proved that, under the right circumstances, you could produce reletively short proteins, about 50 amino acids long, comparetively short to the several hundred, even thousand found in some modern proteins. Anyway, some say that because of this, some organic molecules came together into a cell-like structure. Scientists made these structures in their labs, and even tried giving them modern enzymes: they were used. That means, that when the cells were given the hammer, they used it. Scientists think, through a long and complicated process, which you can learn about, life started to turn into the first Monerans, which gave way to Protists, etc.

    You don't have to read the above

    That's what i learned. What do you think about the evolution of life?
    :?

    My question: what do you think about the evolution of life from nonliving things, and how do you think life started? The Panspermea hypothesis, maybe?

    by the way, what is the little bar under my name, and how do i get it larger?


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    there is plenty of evidence for a limited version of panspermia, as smallish organic molecules (amongst them simple amino acids) are know to have formed in interstellar space

    these are thought to remain after planet formation in comet-like bodies, which then are free to rain down on any suitable planet to seed it not only with sufficient water but also the basic building blocks from which life can start


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    How life started on earth? I belive that something hit earth with viruses on it, and eventually evolved into us. But how life started, probably a very large amount of time, by chance, some kind of organism was "accdentally" made by inorganic substences. So how can "all cells come from cells" if there had to be a beggining?
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    Cursory sequence comparison of a broad range of bacterial, archaeal and eukaryotic genomes reveals that the Last Universal Common Ancestor (LUCA) of all three kingdoms of life was most likely a chemoautotroph that lived in oceanic sulfur vents. The chief difficulties in formulating a complete theory of abiogenesis lie in finding and eventually reproducing the creation of the intermediate steps between a primordial biome largely composed of RNA/immediate RNA derivatives and the LUCA. Currently, the most popular speculation is that modern cells arose as a product of the following rough sequence of developments:

    RNA was first synthesized on Earth along water-ice interfaces.
    The earliest forms of self-replicating units were single RNA polymers that formed and stabilized by self-catalyzed aggregation.
    Amino acids and polypeptides, present by spontaenous formation from Earth's reducing atmosphere, were initially incorporated as ribozyme cofactors. Eventually the amino acids became the primary catalytic components of the machinery because of their greater specificity and diversity. By selection the role of RNA was eventually reduced in many cases to initial assembly of the polypeptide.
    Membranes developed.
    DNA was developed as a method of stabilizing the genome and ensuring higher fidelity in transmission.
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  6. #5 Re: How life started: what do you think? 
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    Quote Originally Posted by thacheezinator

    My question: what do you think about the evolution of life from nonliving things, and how do you think life started? The Panspermea hypothesis, maybe?
    Panspermia is not a theory on how life evolved from non-living things. It is merely a theory of how life got transported from one environment in space to another.
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  7. #6  
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    Nobody knows.
    Some people think that life camed from other planets. some people think it was god and etc. and ....
    "Everyone thinks of changing the world, but no one thinks about changing themselves."John Randolph
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    Panspermia does not solve any riddles, it just creates new ones and explains nada. The usual loonies make a lot of money and milk that idea like this Swiss guy von Däniken.
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    I have no basis for my idea. I always felt life is a result of some extraordinary chemical reaction.
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    The question; What do you think? How life started...

    *Abiotic Synthesis of Organic Molecules*, suggest three ways possible.
    1- were synthesized from inorganic compounds in the atmosphere.
    2- rained down on earth from space.
    3- were synthesized from hydrothermal vents on the oceans floor.

    Earth formed an estimated 4.6 billions years ago, in a Universe said to be 14.2 billion years old. Earths Atmosphere and oceans were formed at arguably at different times in this history, but with out question, they were quite different in make up compared to today. Heat or electrical charge, pressures and water/vapor, should have been present.

    We know that some forms of microscopic life existed, 3.5 Billion years ago from petrified fossil remains. We also think life mutates to the conditions that exist or ceases to exist at all. Those conditions have changed over the past 3.5 billion years, to extremes to say the least. We have an idea of what some forms can survive in, from ocean depths with pressures and heat to frigid climates that never reach freezing temperatures and to areas with no water or rainfall. Many complex forms also, today live under these extreme conditions.

    My current opinion; No.3...Where heat and elements from the earths core could reach both extreme pressure and heat to fuse the amino acids and elements for life. For some time my personal opinion has been organic matter momentarily or for some time does exist during any formation of inorganic matter, forming continuously and dieing for lack of conditions to survive.
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    Quote Originally Posted by jackson33
    The question; What do you think? How life started...

    *Abiotic Synthesis of Organic Molecules*, suggest three ways possible.
    1- were synthesized from inorganic compounds in the atmosphere.
    2- rained down on earth from space.
    3- were synthesized from hydrothermal vents on the oceans floor.
    There are many more.
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    Quote Originally Posted by Twaaannnggg
    Panspermia does not solve any riddles, it just creates new ones and explains nada.
    On the contrary, if true it explains how life on Earth got started. If that is how it did get started then that is an important fact. Rejecting it because of inappropriate use of Occam's razor is not good science.
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    It still doesn't explain how life got started.

    It would be the equivalent of how rats ended up in the Americas.

    Obviously it is quite interesting to know how, but it is a different kind of question that how life got started.

    As in it is a question on a different level. And although it might give the answer on how life migrated to earth, it totally leaves open the mother of all question in biosciences. How life starts.

    As such I am deeply disappointed in the panspermia theory. Not because it couldn't be true, but because it just is a bit like decaf coffee.
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    I'm satisfied with Stuart Kauffman's synthesis: "whenever a collection of chemicals contain enough different kinds of molecules, a metabolism will crystallize from the broth".

    "At it's heart, a living organism is a system of chemicals that has the capacity to catalyze its own reproduction"

    "What I aim to show is that if a sufficiently diverse mix of molecules accumulate somewhere, the chances that an autocatalytic system will spring forth becomes a near certainty"

    An "autocatalytic system" is one in which the products speed up the reactions that form the products: "A" catalyzes the synthesis of "B", "B" catalyzes the synthesis of "C" and "C" catalyzes the synthesis of "A".

    From, "At Home in the Universe" by Stuart Kauffman.
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    Quote Originally Posted by Ophiolite
    Quote Originally Posted by Twaaannnggg
    Panspermia does not solve any riddles, it just creates new ones and explains nada.
    On the contrary, if true it explains how life on Earth got started. If that is how it did get started then that is an important fact. Rejecting it because of inappropriate use of Occam's razor is not good science.
    I am not rejecting it due to Occams razor. The problem with panspermia is that the main problem is still unsolved. How the hell did some self replicating molecules spring into existence? And this does not get any better by putting this process somewhere else. So you need a planet - or place if you want - with the same or very similar conditions like on earth. There is - as of yet - no conclusive evidence that there are any planets resembling Mother. So you need a rocky planet with liquid water on the surface i.e. a "Goldilocks Zone" orbiting around a G-class star. Then you most likely require a large moon around this Goldilocks Planet that stabilized it's orbit and creates swirling in the water so the chemicals get a good stirr. So now you have self-replicating chemicals forming, maybe in some double-layeres spheres of fatty acids or the like. How do you get those off a planet intact? I'd say an impact event has the energy to do that. Would you wanna ride on a piece of space debris flung out into space with anything between 7 to 20 km/s?Let's make no mistake, I know how durable some spores of life on earth can be, they survived a trip to the moon and back. But that's only a week, give or take in space. Now let's assume those molecules get off the planet, now they're in deep shit. Whenever passing stars they are showered with ions, heated up and thrown back into deep freeze. A couple of fly-bys and the whole mess get's really ugly for them. And we are talking about some hundreds of millions years in space, this gives you a couple of thousand fly-bys. O.K. assuming that the molecules survive this trip, they still have get to Earth. Problem beeing: extremely high temperatures during re-entry and stunning pressures while impacting.

    I know you are a fan of panspermia but you add up so many obstacles that I assign a pretty low possiblity for this happening.
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    we evolved from bacteria
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    Quote Originally Posted by Twaaannnggg
    I am not rejecting it due to Occams razor. The problem with panspermia is that the main problem is still unsolved. How the hell did some self replicating molecules spring into existence? And this does not get any better by putting this process somewhere else.
    This is irrelevant. If life on Earth did start from panspermia then that is interesting and significant, since it places a different set of constraints on how it originally arose. Just because it does not answer that question it hardly makes sense to reject it out of hand for this reason. It should be rejected if and only if clear evidence against it is found.
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    I haven't seen anything in living organism that warrants an extra-terrestral explanation.

    Maybe that is a good enough reason not to waste brain power on it.
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    How Life started?

    In 1860, Mr. Milton Bradley was a successful lithographer whose major product was a portrait of Abraham Lincoln. When Mr. Lincoln grew his trademark beard, Bradley's clean-shaven portrait was no longer popular. Out of desperation, Mr. Bradley printed up several copies of a game he'd invented called, "The Checkered Game of Life." Its immediate popularity put Milton Bradley in the game business.

    In 1959, Milton Bradley executives asked freelance toy and game inventor, Reuben Klamer, to come up with an appropriate game for the 100th anniversary of the company. Inspired by a "Checkered Game of Life" game board he saw in the Milton Bradley archives, Klamer and a co-inventor developed THE GAME OF LIFE that was introduced in 1960.
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    Ribose cannot stably form under conditions found on Earth.

    http://www.dls.ym.edu.tw/ol_biology2...Synthesis.html

    At the end of a week, Miller used paper chromatography to show that the flask now contained several amino acids as well as some other organic molecules.

    In the years since Miller's work, many variants of his procedure have been tried. Virtually all the small molecules that are associated with life have been formed:

    ~all the amino acids used in protein synthesis

    ~all the purines and pyrimidines used in nucleic acid synthesis.

    ***But abiotic synthesis of ribose - and thus of nucleosides - has been much more difficult.


    One difficulty with the primeval soup theory is how polymers - the basis of life itself - could be assembled. In solution, hydrolysis of a growing polymer would soon limit the size it could reach.

    Abiotic synthesis produces a mixture of L and D enantiomers. Each inhibits the polymerization of the other. (So, for example, the presence of D amino acids inhibits the polymerization of L amino acids (the ones that make up proteins here on earth).

    Panspermia pushes the interesting question one step further away, and is unsatisfying for that reason. However, it does seem necessary to consider it as we have been unable to model a means under which ribose could have survived on Earth long enough to become part of a self-replicating molecule.
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    Quote Originally Posted by Ophiolite
    This is irrelevant. If life on Earth did start from panspermia then that is interesting and significant, since it places a different set of constraints on how it originally arose. Just because it does not answer that question it hardly makes sense to reject it out of hand for this reason. It should be rejected if and only if clear evidence against it is found.
    I am not rejecting it outright but I state that this does not explain HOW those molecules formed. There are in my oppinion just too many problems transferring those pre-life forms here. The set of constraints can not have been terribly different from what we have on earth. E.g. it's extremely unlikely that the pre-forms (for simpicity let's call it that way, shall we) of life evolved in an environment with liquid methane or ammonia as a solvents. And I think we can both agree that we need some form of solvent, nay? So we need an environment with at least some water in liquid form. This rules out any gaseous planet or some asteroids. A planet that holds liquid water must be approximately Mars-size or larger but not very much larger than e.g. Neptune or Uranus. There is still no evidence for this. I guess there will be in a couple of years when the OWL will see first light. And my personal oppinion is that there is life out somewhere (just my gut-feeling here, nothing else. Just consider the enourmous number of stars in the Milky Way alone and then there seems to be the tendency that at least 1% of all those stars have planets. You could call it "belief" if you must, allthough I have a problem with this expression). There is still the main problem: How to get from A to Earth????
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    we all know the earth is 4.6 billion years old durning the first .7 billion year in the earths existance earth was being pownded by space rocks The energy released by the largest impacts was sufficient to evaporate the oceans. and destroy eny existing life on the surface

    the first sign of life known is about 3.5 billion years ago
    Assembly of the first cellular life on the prebiotic Earth required the presence of three essential substances: water, a source of free energy and a source of organic compounds.
    watter is needed for all life to survive today and its very unlikely that life can exist without it the watter on earth most likely came from comots
    organic compounds can be made from the constituents of the prebiotic soup and the enviormental conditions that took place
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    Spurious sees no need or evidence for panspermia. I point to the apparently rapid appearance of complex cellular life on the Earth, almost as soon as it had cooled down enough to admit permanent liquid water.
    I find the emegence of that life in an astronomically short time period questionable until and unless plausible specific pathways for the origin of those first complex cells, within such a time period, have been identified.
    I am here calling prokaryotes complex cellular life, since the structure, biochemistry, metabolism and behaviour of these is orders of magnitude more complex than any simple chemical reaction.
    Thus, until and unless we establish a plausible mechanism in detail for abiogenesis in the time period and environments of the early Earth, it is appropriate to consider the option of panspermia.
    Quote Originally Posted by Twaaannnggg
    So we need an environment with at least some water in liquid form.
    Typically people think of panspermia in terms of life originating on another planet then being transferred here, by some means, through interstellar space.
    I find much more likely the prospect that life originated in space, within hot Giant Molecular Clouds. These provide liquid water, a complex pre-biotic chemistry, and a mass of reaction surfaces on dust motes that are many orders of greater than that available in the primeval soup of the Earth, couoled with a substantially longer time frame.
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  24. #23  
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    Quote Originally Posted by Ophiolite
    Spurious sees no need or evidence for panspermia. I point to the apparently rapid appearance of complex cellular life on the Earth, almost as soon as it had cooled down enough to admit permanent liquid water.
    That's speculation I'm afraid. We have no clue about the timeframe it took.

    Moreover, the very nature of life is that once it first appeared and evolved to be suitable for a large environment, such as an ocean, it would have become plentiful within a biological timeframe.

    And biological timeframes are much shorter than geological ones.

    I can put one bacterium in a large Erlenmeyer and put it in the 37 degree incubator, and voila! The next day the mass of bacteria is so dense, you can't even see through the media anymore.

    I could isolate all individual bacteria from this one Erlenmeyer and transplant each of them to a new one, and the next day, or the day after that, or the day after that, or if you are a pessimist, a week after that, I would probably have enough bacteria to cover the earth a meter thick.

    Now, a week is a very short period on any time scale, but especially on a geological one.

    So, the appearance of life in itself is expected to be a rapid event on a geological timescale.

    Complex cellular life didn't appear immediately. That took what? 1,5 to 2 billion years!

    First bacteria-like organisms around 3 billion years ago (give or take a few hundred million years), the first Eukaryotes, around 1,5 billion years ago, give or take a few hundred million years ago.

    Hardly rapid.

    Then first multicellular life: that would be some red algae colonies, but first multicellular animal life...POP...there it was.

    You see, one characteristic of life is that it reproduces with exponential characteristics.

    It's within the range of expectations to see life pop up.

    You say life appeared when first liquid water appeared, but this is of course not true. Nobody knows exactly when the first liquid water appeared, and moreover nobody knows exactly when the first life appeared.

    Moreover, life didn't need to evolve in liquid water bodies, it could also have evolved in microenvironments and then spread to oceans, puddles, etc. There might have been conditions that allowed for liquid water before the arrival of liquid water bodies.

    And the quick arrival of life is only a problem if you believe that life arose by chance. Obviously it didn't.
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    Quote Originally Posted by spuriousmonkey
    That's speculation I'm afraid. We have no clue about the timeframe it took.
    Anything about the origin of life is speculation at present. There are serious issues concerning how it could arise in less than 200 million years. (I base the 200 million figure on these two premises: the dating of the first evidence for life and the end of the Heavy Bombarment phase.)This appears to be an astonishingly short time frame to go from simple chemistry to advanced, complex, replicating organisms.

    I am not employing an argument from incredulity. That would be the case if I said I do not believe that a particualr process could lead to abiogenesis. No probable process has been offered with sufficient supporting evidence and detail to make it tenable as more than speculation.

    I suspect that at some point we may well be able to demonstrate that the origin of life is both quite straightforward, inevitable and commonplace. Until we have demonstrated that then the alternatives must also be considered.
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    Quote Originally Posted by manadude2
    we evolved from bacteria
    Virus are very important to our existence, some saying with out virus we or any complex forms, would not.

    Molecular Virology, with an Article 'Origin of Viruses', implies virus evolved with their host. The article also spells out this outline;

    4 BY ago, life originates in oceans and shallow pools.
    3.5 BY ago, Bacteria emerged to colonize land.
    1 BY ago, fungi slowly colonized land.
    700 MY ago, insects and 350 MY ago vertebrates etc....
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    What ever existed as life, on the planet was nearly wiped out in a series of Ice Ages ending near the end of the 'Permian Period, 250 million years ago. Douglas Erwin, in his book, 'Extinction' describes an opinion on "dramatic and deadly, environmental changes". In short, very cold to very warm, oxygen atmosphere with tropic like conditions far north and or south from where they now exist.

    These conditions in changing quickly should allow for quick evolution, I would think. Certainly life forms did during 240-65 million years ago, with the variety of life known to have lived.

    Whatever caused the extinctions of the Dinosaurs and much of the life around 65 Million years ago, conditions again changed. Grass evolved, possibly allowing mammals, oceans cleared up, allowing sea life to evolve and not much later primates made their appearance.

    IMO, bombardment of space debris would coincide with atmosphere forming. Ice Ages, go back nearly a billion years, where the earth is thought to have been a snow ball from about 800 to 600 million years ago.
    To create these conditions, there would have to be a think atmosphere, not only to produce the ice, but to prevent solar heating.
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    Quote Originally Posted by spuriousmonkey
    I haven't seen anything in living organism that warrants an extra-terrestral explanation.
    How can you tell? I mean, until we find some sort of extra-terrestrial life, we have nothing to compare to.



    As for the topic of the thread, isn't it "How life started" not "How life started on Earth?"

    If so, then the argument about Panspermia is a waste of time, since it doesn't regard the explanation of the origin of life, it only regards its supposed proliferation across the universe.
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    as many people say life begun many years before dinosaurs evolved and thats all I know
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  30. #29  
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    Quote Originally Posted by Ophiolite
    Quote Originally Posted by spuriousmonkey
    That's speculation I'm afraid. We have no clue about the timeframe it took.
    Anything about the origin of life is speculation at present. There are serious issues concerning how it could arise in less than 200 million years. (I base the 200 million figure on these two premises: the dating of the first evidence for life and the end of the Heavy Bombarment phase.)This appears to be an astonishingly short time frame to go from simple chemistry to advanced, complex, replicating organisms.
    200 million years sounds like an awful long time for life.

    That's a zillion generations.
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    My theory is that we all came from Alien Skeet.
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    Quote Originally Posted by spuriousmonkey
    200 million years sounds like an awful long time for life.

    That's a zillion generations.
    The problem is building a coherent metabolism and replication system from 'nothin' in that time frame. Once you have a minimal system then I am comfortable in building a nice range of eukaryotes using, extensively, horizontal gene transfer as proposed by Woese. It is getting to that base organism - an organism that is already orders of magnitude more complex than the prebiotic chemistry it arose from- that we do not have a clear path for. That is what may (or may not) take much more than 200 million years. Until we can demonstrate it can be done in that time frame, or less, then the pan spermia option should remain one for active consideration.
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    My understanding is that the base 'organism' requires little more than a membrane and a self - replicating molecule.

    I also am given to believe that there are only a handful of biochemical reactions (perhaps 10) that were required by the last universal ancestor. This is deduced through phylogenetic and other analysis.
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    That is one hypothesis. It is not a consensus hypothesis. It is not well validated. It is, therfore inconclusive. Until and unless a plausible, probable mechanism for attaining the first effective cellular organism is worked out then the pan spermia hypothesis remains valid by default and should be given due consideration.

    While I do not concur with the wilder specualtions of Hoyle and Wickramasinghe I would point out that their predictions, based on pan spermia, that organic compounds would be commonplace in gas clouds and on comets has been borne out by subsequent observations.
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    how common is liquid water, the basis of organic life, in gas clouds and comets?
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  36. #35  
    Universal Mind John Galt's Avatar
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    Probably commonplace in hot GMCs. Present in comets on close approach to stars.
    I am not positing comets as a site of abiogenesis, but as chance carriers of prebiotic chemicals acquired from the collapsing GMCs from which solar systems form. The point is that Hoyle et al said these chemicals would be out there; astronomers in general rejected the idea; today we know he was right.
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    Tangent:

    http://www.spacetelescope.org/news/html/heic0807.html

    Moderator addition: brief extract from link.

    The NASA/ESA Hubble Space Telescope has made the first detection ever of an organic molecule in the atmosphere of a planet orbiting another star. ...The tell-tale signature of the molecule methane in the atmosphere of the Jupiter-sized extrasolar planet HD 189733b has been found with the Hubble Space Telescope. ....Although methane has been detected on most of the planets in our Solar System, this is the first time any organic molecule has been detected on a world orbiting another star.
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  38. #37  
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    Been thinking about this for awhile but life may have found it more favorable to begin in the deepest parts of Earth's oceans, around those hot thermal vents emanating from below the ocean floor. Sunlight wasn't required and the hydrosphere deep in the ocean may have been a lot less volatile than the atmosphere at the surface, I don't know.

    Perhaps someone could shed some light on this. I'm not sure if water can reach the Earth's core where life could have formed or if the early deep oceans were warmer than today. Either way life may have been more equipped to take hold in very deep water than in a surface pond or puddle.

    I've always thought that creatures living around smokers or deep ocean hot spots evolved from animals that lived in shallower waters but is it possible that it may be the other way around?
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  39. #38  
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    Current consensus (i.e fashion) is that the first life probably evolved around the black smokers on the mid ocean ridges (or their Archean equivalent). Darwin's warm little pond has fallen into disfavour.
    On the other hand, two years ago, David Deamer presented data casting doubt on the hydrothermal vent hypothesis. (http://royalsociety.org/news.asp?id=4154)
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  40. #39  
    Forum Cosmic Wizard spuriousmonkey's Avatar
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    Quote Originally Posted by Ophiolite
    Probably commonplace in hot GMCs. Present in comets on close approach to stars.
    I am not positing comets as a site of abiogenesis, but as chance carriers of prebiotic chemicals acquired from the collapsing GMCs from which solar systems form. The point is that Hoyle et al said these chemicals would be out there; astronomers in general rejected the idea; today we know he was right.
    So you are willing to exchange the idea that life has originated on earth over a vast timespan of 200 million years or more, for the idea that life originated somewhere else.

    Hopped onto a comet.

    Managed to survive.

    managed to hit planet earth, while not being destroyed and accidently entering a favourable microenvironment.

    I'm sorry, but I don't see why we should exchange a very feasible notion for a sequence of unlikely events, moreover, a sequence that doesn't explain anything.

    And the fact that there are so many chance events that actually happened in the panspermia theory, the theory also suggests that life most have been seeded on all planetary bodies in this solar system: the carrier must have been common and robust.

    That one is easily tested: as in life should be common.

    And it appears not to be.

    And it still doesn't explain the origin of life.
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  41. #40  
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    Quote Originally Posted by spuriousmonkey
    So you are willing to exchange the idea that life has originated on earth over a vast timespan of 200 million years or more, for the idea that life originated somewhere else.
    I am willing to maintain, in parallel, the possiblity that life originated over a time span of five billion years or more (increase factor by 2.5 orders of magnitude) within one or more GMCs (increase volume factor by 10 orders of magnitude at least).
    Quote Originally Posted by spuriousmonkey
    Hopped onto a comet.
    Inevitable if life originated in the GMC that some of it would wind up on a comet.
    Quote Originally Posted by spuriousmonkey
    Managed to survive.
    Why do you think that would be a problem?
    Quote Originally Posted by spuriousmonkey
    managed to hit planet earth, while not being destroyed
    It has already been established by experiment that there is no particular difficulty in surviving re-emtry from a small sbody such as would emerge from the break up of a comet. (And those buggers break up as soon as you look at them.)
    Quote Originally Posted by spuriousmonkey
    managed to hit planet earth, while not being destroyed and accidently entering a favourable microenvironment.
    That would be a favourable microenvironment created by the impact by thousands of its siblings.


    Quote Originally Posted by spuriousmonkey
    I'm sorry, but I don't see why we should exchange a very feasible notion for a sequence of unlikely events, moreover, a sequence that doesn't explain anything.
    I agree. which is why I favour pan spermia over the inherently flawed terrestrial abiogenesis.

    Quote Originally Posted by spuriousmonkey
    the theory also suggests that life most have been seeded on all planetary bodies in this solar system: the carrier must have been common and robust.
    That one is easily tested: as in life should be common.
    Keep your eye on Mars. I shall be amazed if we do not turn up evidence for ancient life and merely disappointed if we do not find current life.
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  42. #41  
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    What's the point of arguing panspermia in an "origin of life" thread? Panspermia, even if it is ever proven, is only a transport/dispersion method. Maybe the argument over the validity of panspermia should be separated out to another thread, since it's a little off-topic?
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  43. #42  
    Universal Mind John Galt's Avatar
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    My concern centres around the probability of life arising in the short period afforded it on the Earth and in the limited volume of reactive priotic chemicals.
    Pan spermia enhances the likelihood by affording more opportunities, over a longer time period, for life to emerge. This makes it relvant to an origin of life discussion.
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    Eh, I'd say origin of life "on Earth"...but otherwise irrelevant. If we find panspermia to be an essential of life's appearance on Earth, it only shifts the focus to the origins of the transported "life" from panspermia.
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  45. #44  
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    But if that is how it came about - and that is a real possibility - the we need to know it and to determine the details. The fact that it places the problem in another location is no reason to avoid examining the possibility.
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  46. #45  
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    Eh, I'd say origin of life "on Earth"...but otherwise irrelevant.
    As Ophiolite pointed out, if life arrived on earth through pan spermia, the conditions under which it arose would be different. So one can look at how it might have happened under earth conditions (i.e. in smokers, warm puddles, etc) or extra-terran (i.e. on comets, dust clouds, etc.). So it does not simply remove the debate to another arena, it changes the particulars of the debate. That to me makes it worthy of consideration.
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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    Life started most likely out with primitive replicators and evolved thereafter. These replicators essembled randomly, and the probability for that to happen is there. We don't know how primitive replicators can be nor what composition of molecules these primitve replicators require, well, at least not specifically.

    That's what I find most likely.
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  48. #47  
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    If I was to replicate a cell right down to every last detail then I'd probably be looking at a dead cell. I think the OP is concerned with how this jumble of matter became animated. Animated matter is life.

    Basically all lifeforms are machines with power, energy, electronic circuitry and moveable parts at the atomic level, maybe on an even smaller scale. Is the PC I'm using right now similar? I'd say yes, similar but is it primitive in comparison? Not sure.

    We look at life as some strange mystery but in reality it is the universe doing its thing. Life is possible, so it happens.
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