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Space Science

Study Puts Hole In Comet Theory Of Life's Origin 204

Posted by Zonk
from the really-fast-carpool-lane dept.
Astervitude writes "A new study by US and Japanese scientists has put a serious dent into one version of the popular panspermia theory that credits comets for bringing the seeds of life to Earth. Surveys conducted by the University of Arizona, the National Astronomical Observatory of Japan and others now show that objects from the main asteroid belt between Jupiter and Mars were largely responsible for the period of Late Heavy Bombardment that ended 3.9 billion years ago. UA Professor Emeritus Robert Strom believes that no more than 10 percent of the Earth's water comes from comets and any oceans then extant would have been 'vaporized by the asteroid impacts during the cataclysm.'" Interesting, because this directly contradicts the Nova mini-series Origins that just finished running on PBS. Science never stops moving.
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Study Puts Hole In Comet Theory Of Life's Origin

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  • So... (Score:5, Funny)

    by dan dan the dna man (461768) on Saturday September 17, 2005 @06:57AM (#13583694) Homepage Journal
    New study by scientists disagrees with programme made by television professionals to give the illusion of education to the masses?

    Shocking! ;)
    • by sbaker (47485) * on Saturday September 17, 2005 @07:19AM (#13583740) Homepage
      > 80 percent of all studies are wrong...

      Which means that there is only a 20% chance that the study that shows that "80% of studies are wrong" is right.

      Which means that we have no idea what the probability of error is without doing a lot more studies on the subject.

      My head hurts.

      • nxtr: 80 percent of all studies are wrong...

        sbaker: Which means that there is only a 20% chance that the study that shows that "80% of studies are wrong" is right. Which means that we have no idea what the probability of error is without doing a lot more studies on the subject.

        Which means we'll just have to commission a bunch of "scientists" to study the matter further.

        Ain't life grand as a "scientist" at the teat of the government sow? It's a win-win proposition, no matter whether you're wrong or yo

      • Which means that there is only a 20% chance that the study that shows that "80% of studies are wrong" is right.


        That's a pity though. Suppose the study was exactly right. Then the people who did that study have a way to tell which studies are true and which are not.


        All we'd need to do then is submit all studies made to that panel, _before_ publication. We'd get to 100% immediately!


    • Heh that says 50 percent. Regardless, as long as it isn't a negative percentage, Science can move forward. :)
      Think about it. 50 percent is correct. Science builds on itself, therefore as long as at some time, some of the ideas being discussed are in fact correct, science as we understand the term will progress.
      It is a misunderstanding of how Science progresses that would lead someone to think that anywhere near 100 percent of papers discussed were accurate, is needed.
  • Well duh! (Score:3, Funny)

    by Anonymous Coward on Saturday September 17, 2005 @07:04AM (#13583706)
    We all know that the Flying Spaghetti Monster created life, you fools!
  • by sbaker (47485) * on Saturday September 17, 2005 @07:05AM (#13583710) Homepage
    Sure, this is an interesting paper with important ramifications - but I don't see how it has any bearing on the theory of panspermia.

    Surely it only takes one tiny droplet of life-carrying comet water to make it into earth's early oceans without being boiled into sterility. If conditions were right, that initial small pocket of bacteria or virii could multiply to cover the planet in a matter of years.

    You can't tell me that over millions of years and millions of impacts, not one would come down at a sufficiently low speed or favorable grazing angle to gently melt comet ice into an existing ocean.

    Given what we've observed of Mars meteorites ending up on Earth, it's perfectly possible for life from one part of the universe to spread from planet to planet - and even solar system to solar system.

    If you buy into the idea that there was life elsewhere in the universe long before life has been found to have existed on Earth - then panspermia is very possible.

    My problem with that theory is that it doesn't answer any questions about how life formed in the first place. There still has to be an origin world - and explaining how life appeared there is just as hard as explaining how it might have formed here in the absence of panspermia.
    • Yes, but, as you point out, the Problem with the Idea of Panspermia is that it does not explain how life arose -- it just shifts the blame for it (as it were) elsewhere.

    • by Anonymous Coward
      The slashdot summary is misleading at best. Strom et al. are not saying that panspermia is wrong. What they are saying is that most of the water on Earth did not come from comet impacts.
    • by bmgoau (801508) on Saturday September 17, 2005 @07:48AM (#13583803) Homepage
      Increasingly complex molecules competed for energy and material to form larger and more sustainable molecules. The molecules that arranged themselves by chance to absorb the most energy and strongest structure surivied the longest, and this process continued until basic structures combined in a symbiotic relationship that would help sustain the period of those structures existance. This process continues until basic cell structures formed, and again combined by chance to form larger structures. Eventually the strongest and most energy effecient structure was developed by chance through the process of natural selection until we had basic repoductive structures. Mutations which led to longer life and thus more chance of reproduction continued until movement and adaption were constituents, from there entire structures began to work together to from basic cells, which over time developed processes for reproduction and survival through chance combination and mutation. Cells began to grow in complexity in a bid for survival, by chance some began working together to form multicellular groups, which became organisms with adaption relative to the abilities of each cell, then came encoded cellular variation to ensure multicellular groups continued to form by precedence. Over much time increased numbers of simple structures combined to form larger and more complex structures witht he ability for their own kenetic movement beyond growth, because of the natural selection of moveable multicellular organisms made them more adaptable then others and thus more likely to reproduce. Eventually all sorts of mutation and chance combination occured which would lead to ever more complex structures with better adaptability till the first regonizable biological systems formed. From there we have basic sea life and countless steps later down the evolution chain, human beings.

      Of course, it might be out of order, and one would have to know that the time this would take would be immense.

      For those who make the chance argument, stateing that such complex structures canot possibly arise by chance i say:

      Look at the size of the universe, there must be at least 125 billion galaxies, each with roughly 100 billion stars, each with the possibility of terrestrial planetoids, each with a massive surface area with plenty or energy and materials for the possibility of forming the molecular strutuces by chance that are a prelude to life. Then take that number, and times it by the age of most galaxies.....All of a sudden the chance doesnt seem so small.

      As for complexities, whos to say life is complex, its equally possible that life is mearly countless basic systems working symbiotically for the goal of survival and reproduction. I give the cargo cult as ana example: In World War 2 several tribes worshiped American cargo planes because the ability and complexities of human flight were so vast to them that the cargo planes could only be explained as items of a supernatural nature. It never appeared to them that these planes were not godly and no complex beyond their understanding, such is a cargo plane simply a number of systems discovered by humans by chance working in parrallel.

      As for thurther complexity: If life is so complex that the possibility of chance is so small, then how does one explain oru manipulation of life, for example insulin producing bacteria, or the mapping of the genome. How does one explain the evolution and appearance of new viruses and bacterial strains by chance.

      Life is beautiful, it is wonderous and magestic, but it is not beyond our understanding. It arose by chance, it's growth is determined by evolution and it is not complex. It just appears that way to some.

      I always think, that maybe the reason ID and creationalists fight progress and science is they think that discovery is taking the magic and beauty away from life. But instead, what they dont realise, is that all it is doing it discovering more beautiful and wonderous details. We are not finding answers, only more questions. We are giving power to ourselves and whatever purpose we serve. There is no need to be afraid, no need to be ignorant, only a need to be open to the wonders that surround us and fuel the need for discovery that comes with conscienceness.
      • %60 of systems seem to be binary or trinary, not good for life to develope. Planets would need to be in the "goldylocks" zone where water is liquid much of the time. And there are about 5-6 other factors that would limit development of life elsewhere. There will still be a lot of good planets, but not anywhere near as many as you suggest.
        • I never suggested that the enviroment neccisary for life would be common, i mearly stated that given the scope of the universe it is probable that many systems like ours could exist. Of course, given lifes adaptability, it is ignorant to assume that the environment here is the one specifically needed for life. for instance we have already seen life in cave that never see light, and entire ecosystems surviving off the heat from volcanic vents.

          Life will find a way, and given the scope of the universe, even if
        • OK - so 125 Giga-galaxies times 100 Giga-stars per galaxy times...what...2 planets per star on the average?

          That's maybe 25,000,000,000,000,000,000,000 planets. ...any you're claming the problem is that 60% of those are uninhabitable because or binary stars? Oh dear...only 12,500,000,000,000,000,000,000,000 left.

          • Proteins are made from amino acids. Twenty types of amino acids are arranged in a specific order to make a particular protein or enzyme. Let's look at a simple protein - say 100 amino acids long. Let's be optimistic and say that all twenty needed amino acids are available in any quantity. Well, now we need one of twenty different amino acids to join with one of twenty others, then have that join to one of twenty others, and so. 1/20 * 1/20 * 1/20 * ... for one hundred amino acids. Multiply it out - it's 1 c
            • Right, because out of those uncountable number of possible arrangements for proteins, the only ones possible for life are the ones we use.

              Did it never occur to you that perhaps we don't use the proteins we use because they are the only molecute capable of the job, bu merely because they are the ones that were at hand?

              Don't be so damn arrogant and idiotic assuming that what you see is all that is possible.

              There are countless billions of potential protein arrangements that could help life arise - we just happ
        • %60 of systems seem to be binary or trinary, not good for life to develope. Planets would need to be in the "goldylocks" zone where water is liquid much of the time. And there are about 5-6 other factors that would limit development of life elsewhere. There will still be a lot of good planets, but not anywhere near as many as you suggest.

          These requirements are a myth. Even with the assumption that life requires liquid water, the idea liquid water only exists within a 'Goldilocks' or 'just right' zone based
    • by StuckInSyrup (745480) on Saturday September 17, 2005 @07:50AM (#13583807)
      If conditions were right, that initial small pocket of bacteria or virii could multiply to cover the planet in a matter of years.

      I do not disagree completely, but one word is definitely wrong in this sentence. Virii.
      A virus is a parasitic lifeform, that "lives" only inside of a living cell. No cell - no life, no multiplication, no evolution and no spreadnig. Outside of a living cell a virus is an inactive lump of protein and nucleic acid.
      Other tahn that, a virus is a potent driver of evolution by mixing up its host genome, possibly creating new genetic structures.
    • Well, the panspermia theory is a bit like intelligent design - it is not one theory, but several theories, however, the panspermia theories have a chance to be proven true, while the ID theories tend to be proven wrong.

      Examples:

      - the cosmos helped life come into existance by simple organic molecules that were
      - formed in space
      - ejected from a planet

      - life spread through our solar system, that is:
      - from mars
      - the asteroid belt was formely a planet hosting life which

      - DNA/RNA ca
    • don't see how it has any bearing on the theory of panspermia.

      It doesn't. According to TFA:

      Comets have played a relatively minor role in inner solar system impacts, Strom, Malhotra and Kring also conclude from their work. Contrary to popular belief, probably no more than 10 percent of Earth's water has come from comets, Strom said.

      10% of Earth's water is a FUCK of a lot of water (137 million km3); and in that you only need one living cell to colonise the whole planet in a very short time geologically. It

    • A human fault and trait, we always are programmed to believe in a beginning and end.

      Whos to say that the universe isnt infinite in age, and life always was here, (15b age is a theory, what if we just cant see past 15b LY)

    • I thought the same thing. All it takes is for one single comet to break off piece that has life on it that is small enough to land in an ocean without vaporizing itself.

      Besides, I though it was proven that amino acids can survive impact, along with leptides. Someone should run that same test with spores and single cell life.
    • Panspermia would require life to have arrived in a rather narrow window of time, between the last time at which the Earth's oceans were boiled by an impact, and the earliest time at which life was known to have existed. The simulation suggests that this would not have been a time at which many comets were hitting Earth, which, while not conclusive, is not supporting.
  • by Otheus (897195) <otheus AT gmail DOT com> on Saturday September 17, 2005 @08:05AM (#13583840) Journal

    First, there is panspermia, the notion that microorganisms evolved independently of earth's atmosphere and, probably via comets and/or asteroids, seeded earth with the life -- not just the building blocks, but life itself.

    Second, there is the comet-abiogenesis link, the notion that comets contain the organic molecules, (chains of hydrocarbon and methane) which, in abundance in the right conditions, will form monomers, which will form polymers, which form peptides, which form nucleic acids, which form RNA, which forms DNA. Note, this happens every single second in every living being. Abiogenesis is when this reaction happens outside of a life-form. Scientists are quite close (as I understand it) to seeing abiogenesis (in controlled conditions) in the lab, and the theory more or less hinges on the abundance of the comet-supplied raw materials.

    Third, comets are not meteors! They are fundamentally different as the recent NASA mission Deep Impact proved. (Initial reports indicate) comets do indeed contain the building blocks believed to be required for abiogenesis. They also contain ice. In fact, they are mostly large-holed sponges of ice.

    So on the one hand, you have some scientists saying that water came from comets. (But all water? I wasn't aware of that hypothesis, but perhaps it was not a popular one.) Then you have the scientists quoted in the article here on Slashdot, that the water did not originate from comets because the meteors would have vaporized all the water from the comets, and so water must have come from somewhere else. This does not directly compete or refute with either the comet-abiogenesis hypothesis or or the panspermia theory. Both of these theories are compatible with water already existing on the earth anyway.

    Now, as far as the scientist's hypothesis, that the meteors would have vaporized all the comet-borne water? There are two problems with this. First, the water on earth must have come from somewhere. If there was water on the earth before the meteor-bombardment, then that water also would have been vaporized! So water came after the bombardment. Now if the paper is saying that comets could not have supplied the earth's water, they have contradicted themselves. The earth has water, the meteors vaporized the water 3.9 B years ago, therefore the water came from somewhere else. And as was shown by Deep Impact, comets are really mostly porous ice, which means they would not have impacted the earth and left scars in the same way meteors do. In fact, the meteor impacts of earth may have left no signs at all, other than the presence of water and organic material.

    • by cowscows (103644) on Saturday September 17, 2005 @09:21AM (#13584068) Journal
      Say there was an ocean on earth, and something big slammed into it, vaporizing all the water. Wouldn't that water just eventually precipitate back down?

      I mean, vaporizing something like a person would pretty much destroy them, but it doesn't do much to eliminate individual atoms, it just moves them around. So the ocean itself might be turned into water vapor, but then where does that all go?

      I'm sure a big enough impact could blow matter up into space, where it'll float away never to bother the busy earth again, but I would think that most matter gets propelled outwards from an impact, not up. So wouldn't a meteor hitting an ocean just spread the water around?
    • the meteor impacts of earth may have left no signs at all, other than the presence of water and organic material.

      comet impacts

    • Water gets vaporized on earth all the time.

      Then it comes down as rain.

      I don't see any problem with the theory that "organic matter" came to primative earth from comets, mixed with water, which was vaporized, then condensed, then that "organic matter" became the building blocks for life.

      But at that stage of earth's life, there's little distinction between a comet and earth. They're both big hunks of rock and ice floating in space. I'm sure some "organic matter" originated on earth too. What they're saying
      • Not until someon invents a time machine, or until we discover a new primordial planetary system to observe.

        Bingo. We'll just have to observe that primordial planetary system, won't we? Just because a theory is difficult to observe currently (as opposed to invoking supernatural stuff), doesn't mean we shouldn't consider them.

    • "And as was shown by Deep Impact, comets are really mostly porous ice"

      All right, you tried this once, and I let it go. I had to call you on it the second time however.

      The Depp Impact mission suggested just the opposite of what you say, that there was very little ice in that particular comet.

      I don't know how you drew your conclusions, but they are incorrect.
  • by G4from128k (686170) on Saturday September 17, 2005 @08:22AM (#13583875)
    Although the panspermia theory is intriguing, it does NOT answer the question of the origin of life -- was it from another planet that was inoculated by an even earlier comet..... It's like the theory that the Earth rides on the back of a giant turtle/ But what does that turtle ride on? Or is it turtles all the way down.

    If we are to assess the probability that life is exogenous or endogenous to Earth, we must ask about the relative probability of: a) life forming on a planetary body versus b) life forming on a planetary body which then survives being blasted into space, travelling interstellar distances, happening to collide with another forming planet of just the right composition (without ever venturing too close to some hot star), and surviving that collision.

    Even if the probability of life arising on a planet very very low, the relative probability of endogenous versus exogenous origin is very skewed toward endogenous origin. Because exogenous origin requires both endogenous origin (somewhere else) and then a low probability trip between planets, exogenous origin would seem to be very unlikely unless there are large numbers of planets with endogenous life that spew lots of interstellar-traversing chunks. But if there are large numbers of planets with with their own endogenous life, then the probability of life forming on Earth endogenously must also be high and trump the low likelihood of life just happening to make it from somewhere else.
    • Your argument has merit - but you are assuming that all planets that might be postulated as the ultimate origin of life are earth-like.

      You might argue (although I personally would not) that the probability of life spontaneously arising on a world with the precise parameters of early earth is Pe - but the probability of it arising on a planet with different parameters of atmosphere, composition, temperature, gravity, radiation - is larger than Pe. Call this probability Px (probability of life forming on pla
      • Thank you. That was lucid and interesting.
      • So whilst the probability of life travelling between worlds might be some low probability (call it Z), then it might still be that Z.Px.Tx > Pe.Te - which would make exogenesis (panspermia) more probable than endogenesis.

        That's a very interesting argument. I would suspect, however, that Z is such a small number as to swamp all the other terms. A panspermic chunk must gain enough velocity to escape the gravity well of its planet AND star yet not have so much velocity that it doesn't get captured by
        • I agree that you can argue (quite successfully in your case) against my gut feel for the magnitude of the numbers - but you have to agree that there is enough variability in there that we cannot possibly rule out exogenesis because it's "obviously" less likely than endogenesis as the parent to my post suggested. It's perfectly possible for exogenesis to be overwhelmingly more probable.

    • Although the panspermia theory is intriguing, it does NOT answer the question of the origin of life -- was it from another planet that was inoculated by an even earlier comet..... It's like the theory that the Earth rides on the back of a giant turtle/ But what does that turtle ride on? Or is it turtles all the way down.

      I'm not seeing the point of your post. Earth life may have originated elsewhere or not. Are we supposed to ignore theories that are difficult to observe (rather than impossible like some

  • And yet, when fighting alternative models like "Intelligent Design", everyone pretends scientific findings were cast in stone.
    • I have seen almost no scientists that present science this way, even to the general public. And this uncertainty is something proponents of ID (or deniers of global warming, to address the other reply to this) sieze on and say "Scientists have no idea, they change their minds all the time, so they must be completely wrong." Yes, science never stops moving, but complete reversals are rare and come about when the evidence is there. The more common scenario is that scientific understanding slowly advances, cha
    • And yet, when fighting alternative models like "Intelligent Design", everyone pretends scientific findings were cast in stone.

      Did they? When? I haven't noticed. Funny, but I assumed that the benefit of the scientific approach was that ideas are very definitely NOT cast in stone, unlike the dogma of Intelligent Design, which states that some things are just too complex to have ever evolved.
  • by jaymzter (452402) on Saturday September 17, 2005 @08:37AM (#13583917) Homepage
    That's an interesting comment that glosses over many of the statements of science that are commonly excepted so much as "fact" that anyone that points out inconsistancies in them is labeled as anti-science or ignorant. Of course we are always learning more and yesterday's accepted theories have to adapt to new knowledge, but the virulence some people have for defending pet theories borders on intolerance.
    A good case in point is evolution, where if you don't mention it in a glowing light on /. you get modded into oblivion. Please note I didn't relate it to Creationism or Intelligent Design, it's just that the theory of evolution itself has about as many holes as IE. Sure, right now it's the best idea going, but that doesn't mean it's the end of the conversation. Yet questioning it all usually does end the conversation.
    • Really - What holes exactly are you talking about? Oh that's right you have no idea of what you talking about.
    • The problem with the theory of evolution and its vehement and passionate arguments is that it's traditionally argued in a completely un-scientific manner.

      There are people who would want to believe that human beings are *not* animals, and how dare you suggest that we evolved from them?

      There are people who would want to believe that everything was created by the gods in one fantastical story or another.

      And then there are people who want to understand. They argue amongst themselves endlessly, while the other t
    • it's just that the theory of evolution itself has about as many holes as IE.

      Such as?

      Sure, right now it's the best idea going, but that doesn't mean it's the end of the conversation. Yet questioning it all usually does end the conversation.

      I would be interested to know exactly what about evolution you would like to question? That organisms have changed over time? That such changes happen naturally? That the changes result in variety, and from that variety some organisms turn out to be better able to repro
  • From the post:

    UA Professor Emeritus Robert Strom believes that no more than 10 percent of the Earth's water comes from comets and any oceans then extant would have been 'vaporized by the asteroid impacts during the cataclysm.'

    Uhuh, so that one that did get through can use the excuse "wha? criminey, Tara was still virgin, its not supposed to happen the first time!"
    • I forgot to mention that 10% of the earths water is no small amount and it seems to me that water is a decent place to survive cataclysms since you pretty much have to get stranded outside of water before you really notice such world changing events. I mean, if I were a really small organism, thats how it would seem to me.
      Cripes, now I have to RTFA.
  • Life (Score:2, Interesting)

    by bmgoau (801508)
    "If it is just us, it seems like and awful waste of space" - Carl Sagan Increasingly complex molecules competed for energy and material to form larger and more sustainable molecules. The molecules that arranged themselves by chance to absorb the most energy and strongest structure surivied the longest, and this process continued until basic structures combined in a symbiotic relationship that would help sustain the period of those structures existance. This process continues until basic cell structures for
  • I'm actually the reason for the origon of life... You ever forget stuff on a trip? Well, I went back in time and left a pair of old, smelly socks...
  • by technoCon (18339) on Saturday September 17, 2005 @12:00PM (#13584984) Homepage Journal
    "Interesting, because this directly contradicts the Nova mini-series Origins that just finished running on PBS. Science never stops moving."

    Those inclined to believe the Bible and feel skeptical when science apparently contradicts it, should take comfort in the fact that science's story has changed over the century whereas (relatively) the Bible's has not.

    This is does not mean that religion ought to ignore and deprecate science. Things like that Galileo business provide powerful insights into how to interpret scripture. If the Bible says "sunrise" it should be interpreted phenomenologically. That is as an observation of brute phenomena and one should not take that as an explanation of the mechanism that gave rise to the phenomena. (Incidentally, the weatherman is not a flat-earther because he tells us sunrise/sunset times.)

    With this phenomenological principle in mind, someone who believes in the Bible will be able to interpret its statements about God according to that same phenomenological principle. Troubling verses about God "doing evil" are thus explained. To wit, God establishes things like gravity and hydrodynamics that move in predictable patterns. When those patterns conspire to crush us, via tsunami or hurricane, we perceive evil fom God's hand.

    But the character behind these phenomena is more reflective of the scientific principles of natural law.

    I suppose I should ask for an offering at this point. Instead, I'll ask that we all work a little harder at our science so we can better predict natural forces and prepare for them.
    • Those inclined to believe the Bible and feel skeptical when science apparently contradicts it, should take comfort in the fact that science's story has changed over the century whereas (relatively) the Bible's has not.

      As the old saying goes: "Science may be wrong today, tomorrow or ten years from now, but the Bible is wrong forever."
  • by edunbar93 (141167) on Saturday September 17, 2005 @01:08PM (#13585349)
    This theory also directly contradicts another theory I saw this month in Sky and Telescope [skyandtelescope.com], which referred to this article [nature.com]. This one is for the formation of the outer gaseous planets and the kuiper belt. The basis of the theory is that the orbits of all the gas giants should have been closer to the sun, as they would have required a much denser gas-and-dust cloud than would have existed as far out as they are now. As well, the kuiper belt would have formed closer to the sun.

    Due to gravitational interactions between the gas planets and the kuiper belt objects, Jupiter's orbit shrinks and Saturn, Uranus and Neptune expand, with the latter two actually changing place and moving into much more elliptical orbits before settling down into their current orbits. These larger orbits put both planets squarely into the primordial kuiper belt and, well, cause the Late Heavy Bombardment.
  • Nova is known to do documentaries on crackpot and minority theories.

    Using Nova as an educational tool, you are likely to learn about theories that are already proven false or have little evidence backing them up. The documentaries are certainly twisted into a certain point of view and convey information that the scientists they interview wouldn't have agreed with. Especially on topics related to Geology.

    I'd say the same thing about most of the Discovery Channel's content, given the experiences of some sci
  • It only takes a single viable microbial spore from space to start life on a planet. A single impact could have delivered it. Or it could have drived through space without any impact at all. Therefore, where most of the objects impacting on earth originated is pretty much not relevant to panspermia.

    It seems that what that article is talking about is not panspermia, but the composition of the atmosphere and how that was determined by impacts.

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