Study Puts Hole In Comet Theory Of Life's Origin

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.

So why does this contradict panspermia?

[sbaker]

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.

Re:So why does this contradict panspermia?

[bmgoau]

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.

Well, panspermia theory is a bit like ID ..

[RedLaggedTeut]

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 came from space

- bacteria survived a journey through the cosmos

The study reported by slashdot makes some of these theories unlikely, but not all of them.

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[account_deleted]

Comment removed based on user account deletion

Why its not turtles all the way down

[G4from128k]

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.

Re:Why its not turtles all the way down

[sbaker]

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 planet X). But there are lots of planet types out there if we don't know what the perfect conditions for forming life is (and I don't think we do) then Px might be as large as N times Pe where N is the number of planets in the universe. But certainly Px is larger than Pe just because of the range of possible alternative conditions.

Further more, these probabilities might be: "The probability of life forming in any given year" - so the probability of life forming at any time in the past would that annual probability times the available amount of time over which life might have been able to form. Well, if you require endogenesis, then you have only Te==the age of the earth - where exogenesis allows Tx==the age of the universe minus the travel time. I think it's clear that Tx > Te

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.

Since Tx is MUCH greater than Te, and N is such a large number (so Px is much larger than Pe), we can allow Z (the risks due to travelling between worlds) to be tiny and still believe that exogensis is more probable then endogenesis.

Life

[bmgoau]

"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 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 ans

Re:Futile work

[Floody]

Logic, m'boy, logic. If you're gonna spout off psuedo-science like the pros, you gotta get a hold of some logic.

why would man and animals need eyes if they couldn't see before, sight is a very high-level ability, a creature without sight doesn't realise he needs it?

What does "realise he needs it" have to do with anything? Evolution is not intentional, evolution is not a "force". Nothing decides to evolve. A species ability to visually perceive offers many advantages, depending on the environment. Mate recognition, prey recognition, predator awareness, etc.

Also in 'natural selection' humans would have been eaten by everything without sight no matter how developed the brain was.

Which humans? Modern humans? There's no sense behind those ears, boy! Modern humans can create weapons and modify their environment to prevent being "eaten by everything". If you're talking pre-historic humans, I'd be willing to bet that a fair number of them were eaten.

Still, the ability to form even primitive weapons is an amazing advantage. Plus, do you really think people were always as they are today (physically, senses, etc)?

If we came from the ocean then why can't we breath underwater and if we are the most 'evolved' of creatures then why are the birds flying around the earth like it's going out of fashion? We're wingless, can't go underwater without breathing equipment, the ascent of man? Yeah right.

Who judges humanity as the "most evolved?" You? Last I checked, no mammals have gills, and the set of species that is truly amphibious is rather limited and primitve.

How do you propose a warm blooded animal should go about absorbing the incredible amount of oxygen necessary to maintain a fast metabolism with something like gills? What does Genesis 1:1 have to say about that?

I'm sure if these 'scientists' really thought about it, evolution is absured, mutation is more accurate, but I wasn't a piece of garbage from 10000 billion years ago. I mean even micro-biology points to an intended design. How come nobody talks about entropy no more? Oh if we we're the offspring of monkeys then why arn't monkeys turning into humans?

Ahh, here we see the real truth. It's personal, isn't it? You just couldn't possibly have been from genetic lineage decended from something more primitive, could you? News flash buddy: Just because you want something to be a certain way, doesn't make it so.

Your "intended design" is completely and totally without evidence in reality. The so-called "evidence" is nothing more than fanciful thought expirements based on theology rather than logic. Put it this way: any "designer" with the ability to exactingly design all the myriad forms of life is equally capable of "designing" a process by which life can adapt, change and mutate to best suit its environment over time. I suspect that a being with that much power is perfectly capable of making you an "offspring of monkeys", whether you like it or not.

(pssst.. nobody's forgotten about entropy, it's just that we're all sick of listening to very confused creationists try to bend the second law of thermodynamics to fit their will)

this is a religion vs science toll

[technoCon]

"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.

Re:Life

[eluusive]

I don't have time right now to fully read your essay, but I would like to respond to a few points which are erroneous.

• Organic molecules are not extremely stable as you imply. They are very easy to destroy with UV radiation. Which happens to be pretty abundant on earth. It's why you get sunburnt.
• Evolutionary theory does not apply to molecular chemistry. Molecules don't live or die, and the strongest survive to reproduce, while the weaker ones don't get stomped out of existance.
• Genetic errors are more common and probable to pass on than better characteristics. As with any kind of data corruption. (Your floppy disk went bad, you mean your essay has random characters in it instead of shakespeare? Naw) Child diabetes didn't 'evolve' into the human genome after insulin was developed. It's been there for along time, yet the children died very earily in life. (Before they could reproduce.) This is due to the fact that genetic changes in reproductive organs (which are necessary to pass on the error.) don't affect the parent (Thus natural selection doesn't work). While the parent may be a very prosperous individual maybe he has 8 kids. 3 of those kids die from diabetes, another 3 have the gene but it's inactive (and will pass it to their children), and the last 2 don't have it at all. This goes on and on, and it's why we have the genetic problems we do.
• Natural selection does not guarantee that bad genes will be pruned from the genome. It is simply what happens when a subset of a population survives a cataclysm. Those survivors may or may not end up all having the same gene which "allowed" them to survive. You can see how this would be the case from the previous point I made.

Re:Heh.

[Tablizer]

Well, if life can exist there to bring it here why can't it just develop here. Seemed like a big waste of time to me. I see no reason we cannot have a homegrown abiogensis on good old Earth. It's not like we hit some major hitch and need an alternate explanation that explains nothing.

The best place to form and spread from may not necessarily be the best place to grow up. Maybe life on Earth originated in Jupiter's atmosphere or moons, for example, and then spread to Earth. Earth may be a better place to grow more diverse and complicated. It is sort of a "comparative advantage" of life economics.
       

Re:Genesis Therories

[Decaff]

Well, I will point out that the various theories of Creation in the last few hundred years has been far more stable than any scientific theory put forward.

That is because ignorance is stable.

Perhaps it would be better if science types started using rhetoric like "We Think" or "We Believe" instead of "We now know..."

We 'science types' usually do. The problem is that if we start saying 'we believe' too much in public, our ideas get attacked as 'just another form of religion'.

I mean, the version of Darwinism that was taught in my school has pretty much been shot to heck, but my Biology teacher sure enough said, "This is how it happened."

That is because the science taught at school has to be simplified hugely. The version of almost any scientific idea taught at school is largely wrong. The idea is to open minds to the principles of science.

Re:So...

[Guppy06]

No no, we're talking about Nova on PBS, not the Discovery Channel.

Occam's Razor

[kcarlin]

Personally I always hate panspermia. It seemed to fail Occams Razor pretty soundly. Yes, life on this planet came from an asteroid or comet from another planet. Well, if life can exist there to bring it here why can't it just develop here. Seemed like a big waste of time to me. I see no reason we cannot have a homegrown abiogensis on good old Earth. It's not like we hit some major hitch and need an alternate explanation that explains nothing.

Occam [wikipedia.org] provides an excellent mechanism for analyzing and prioritizing hypotheses, not a doctrine for generating prima facie "truths".

The life-from-comets theory was inspired by the discovery of complex carbons in comets (the dirt in those dirty snowballs), molecules that, if found "in the wild" on Earth would be deemed "organic" and that can form basic proteins. It was raised in the face of evidence and models that showed Earth to be a very unlikely place for "life as we know it" to evolve (this could indeed be, and in fact was, considered a "hitch"), and was developed as a theory to broaden the "origin of life" models. We know much more now than we did then and the theory is still a competitive explanation. Theories as rule are typically dead before breakfast.

Life-from-comets is Exogenesis, but not necessarily (or even likely, apologies to the late Sir Fred Hoyle) Panspermia [wikipedia.org]. There is no reason why comet-borne carbon molecules could not survive entry into Earth's atmosphere under some circumstances any more than all meteors are destroyed. Meteors could also theoretically carry endolithic bacteria intact to the surface, though this is difficult to prove with old meteorites on Earth due to the possibility for contamination.

The intriguing part of the life-from-comets theory (which is a specific theory of Exogenesis and doesn't rely on Panspermia) is that the conditions required for the development of life may somehow actually prove to have been a dirty snowball in an eccentric orbit.

Panspermia specifically predicts the interstellar distribution/seeding of life. We are a long way from being able to gather and study interstellar samples. We are a long way from studying the Oort Cloud directly, though we are fortunate to be able to visit the occasional dirty snowball.

And since we started theorizing alternatives to the purely terrestrial development of life (Geogenesis), we have discovered endolithic bacteria and other outrageous but often simple forms of life in places unthinkable even 50 years ago. Time may prove comets unnecessary to explain life on Earth, but exploring all of the ways life might develop and all of the forms it might take is essential to intelligently exploring the Solar System. We may find life or life-like processes in some form everywhere.

Re:How about an old study! The BIBLE!

[anubi]

Try this one on...

Do you believe God made the Universe, Heaven, Earth, and everything in it?

I do.

Science is the word we use to describe our research trying to find God through evidence of his Creation.

You think Man authored the Laws of Physics which scientists hold so dear? Think again. No man set Avagadro's constant, or any of the other parameters of our observable universe.

If God did create us, did he intend us to try to find Him, or mull around like a bunch of obedient ignorant sheep doing the bidding of those who take it in their mind to control us?

Think of what each faction is trying to do. Scientists are trying to understand God's creation and what our place in it is supposed to be. Damn near every religion I have even run across is full of control and obedience to men, often without ANY concrete evidence of truth, just hearsay.

Now, in the BIBLE you referred to, even there, if you take the BIBLE to be literally the Word of God, it is full of warnings of the false prophet.

Personally, I feel a lot closer to my Creator knowing I can see and verify His work, knowing full good and well I am seeing work of intelligent design. I do not feel comfortable at all dealing with people who sell me a relationship with my Creator like they would sell me a speculative stock investment, based on hearsay and faith that its a sound investment.

Maybe I am a bit jaded by now, but it seems all I have seen religions do is fight. I get the idea all this fighting pleases God about as much as I appreciate my cats fighting. Believe me, I derive no pleasure at all in seeing my cats all scratched up, ears mangled, and bloody.

Am I supposed to believe there is a God up there somewhere who tells various factions all over the Earth to gather in his name and smite the other ones?

Or does simple knowledge of human behavioural psychologies and obedience structures indicate the Gods of Religion are just some entity created by men so they could use it to control other men?

If God created me with sufficient intelligence to seek Him, why is he gonna hold it against me for doing exactly that?