Is Panspermia a pseudoscience?

[mr friendly guy]

Panspermia is the the theory that microorganisms or biochemical compounds from outer space are responsible for originating life on Earth and possibly in other parts of the universe where suitable atmospheric conditions exist.

I know Sir Fred Hoyle was apparently a proponent of this theory, yet he was also a staunch anti-evolutionist. How does he propose that micro-organisms led to more complex life if it didn't evolve?

Also of note is the direct panspermia theory proposed by Francis Crick (one of the men credited with the discovery of DNA). He also gets quoted as an anti-evolutionist although it seems he is more critical of the abiogenesis theory rather than evolution itself. Direct panspermia states that aliens seeded the Earth with the ingredients for life. Substitute alien for deity and it sounds similar to any other creation myth.

While direct panspermia sounds like a blatant pseudoscience (like Creationists, Crick seems to attack abiogenesis without actually providing much evidence to support his theory), what about panspermia itself

. Of course even if you accept panspermia as the cause of life on earth, how the hell did the micro-organism from space come about in the first place?

[GrandMasterTerwynn]

Panspermia is the the theory that microorganisms or biochemical compounds from outer space are responsible for originating life on Earth and possibly in other parts of the universe where suitable atmospheric conditions exist.

I know Sir Fred Hoyle was apparently a proponent of this theory, yet he was also a staunch anti-evolutionist. How does he propose that micro-organisms led to more complex life if it didn't evolve?

Also of note is the direct panspermia theory proposed by Francis Crick (one of the men credited with the discovery of DNA). He also gets quoted as an anti-evolutionist although it seems he is more critical of the abiogenesis theory rather than evolution itself. Direct panspermia states that aliens seeded the Earth with the ingredients for life. Substitute alien for deity and it sounds similar to any other creation myth.

While direct panspermia sounds like a blatant pseudoscience (like Creationists, Crick seems to attack abiogenesis without actually providing much evidence to support his theory), what about panspermia itself

. Of course even if you accept panspermia as the cause of life on earth, how the hell did the micro-organism from space come about in the first place?

Panspermia as a theory isn't as shaky as one might think. Recent experiments all indicate that microbes can survive for a very long time in space, given a modest amount of sheltering from ionizing radiation, and provided the impetus that originally launched them into space didn't kill them. They can also survive the landing (a relatively small meteorite will stay quite cold inside . . . protected by the ablation of its outer surface layers.) However, the microbes would still have to have evolved on the world they originally came from, and they have a shelf-life of a some tens of millions of years (the suspected age of some revived bacterial cultures recovered on Earth from amber-entombed insects, cavities in rocks and the like.)

However, the most likely panspermia scenario for Earth doesn't involve anything as exotic as life arriving here from light-years away. It involves life arriving here from Mars (that rocks can get here from Mars is concrete fact. We have meteorites from Mars to prove it.) Of course, like any other panspermia theory, it makes a lot of assumptions . . . such as A) Life evolved on Mars first. B) Life from Mars was transported here fairly early (before Mars dried out and the chances of digging up a Martian rock laden with microbes plummeted.) C) Life arriving from Mars managed to out-compete what native Earth-life might've existed when the Martians landed. So, there's a small chance that at some point in Earth's history, it was host to a successful Martian invasion. There's an even smaller chance that the invasion continues to this day, and that we're all actually Martians.

However, panspermia isn't an alternative to abiogenesis, as abiogenesis would still have had to occur somewhere.

[Drooling Iguana]

Basically, it could have happened, but there's no good reason to believe it did happen. It's possible, but it violates parsimony.

[wolveraptor]

Well, if we found life on Europa, and their microbe's DNA was distinctly similar to ours, we might have evidence that one of the bodies seeded the other.

[Admiral Valdemar]

I don't see anything being against it happening here, but trying to prove it would be difficult if not impossible, much like getting a perfect fossil record. It's good theorising, though that's all it is.

[GrandMasterTerwynn]

Well, if we found life on Europa, and their microbe's DNA was distinctly similar to ours, we might have evidence that one of the bodies seeded the other.

Well, yes. Though material transfer between Mars and Earth is much easier to accomplish. But if Martian bacteria were found to use the same basic biochemistry that our own do, then that would be a pretty strong indicator that life here might've come from there. (Not so much vice-versa, it takes a lot more energy to kick an Earth rock out to Mars, instead of bringing a Mars rock here.)

[The Duchess of Zeon]

Could very simple life have actually evolved on comets? We have evidence, after all, of bacteria surviving in climates--such as near volcanic vents, and even inside of rock--which are at least as harsh and possibly more extreme in the former case than deep space.

[Xon]

Comets arent high energy enviroments like volcanic vents. Thier internal temperatures wouldnt be much higher than the surrounding vaccum.

[wolveraptor]

To form, life needs some modicum of heat for the necessary chemical reactions to take place. Once formed, I'm sure it could survive on comets, but form there? I don't think so.

Maybe the impact comets carrying complex amino acids was what formed life. I distinctly remember an experiment when a sort of metal thermos filled with proteins was impacted or shaken at the force a comet would've hit the earth at. It was on PBS. They found that chains of amino acids had formed in the "soup".

[tharkûn]

Panspermia is a proven hypothesis. Streptococcus mitis has already seeded life onto a lifeless rock while hitching a ride on a space vessel designed by intelligent creatures. I defy anyone to tell me how life arose on the moon without resorting to panspermic theories

There is nothing scientificly invalid about a theory which states that life on earth was seeded from extraterrestrial origins. It is possible (though quite remote) that humanity's current extrasolar probes will eventually do this. Proving it to be more valid than alternatives, on the other hand, would be Nobel worthy science that has yet to be forthcoming.

[Lord of the Abyss]

Of course even if you accept panspermia as the cause of life on earth, how the hell did the micro-organism from space come about in the first place?

IIRC correctly, the idea tied in with Hoyle's beloved Steady State Universe. One of the classic anti-natural abiogenesis arguements is the probability arguement; the claim that the chance of life appearing by chance is so small it would never happen in the life of the universe. Hoyle's idea was that the universe had infinite age, so there was enough time for life to appear by chance.

[Sriad]

Well, if we found life on Europa, and their microbe's DNA was distinctly similar to ours, we might have evidence that one of the bodies seeded the other.

Well, yes. Though material transfer between Mars and Earth is much easier to accomplish. But if Martian bacteria were found to use the same basic biochemistry that our own do, then that would be a pretty strong indicator that life here might've come from there. (Not so much vice-versa, it takes a lot more energy to kick an Earth rock out to Mars, instead of bringing a Mars rock here.)

On the other hand (and I'm not at all an expert, mind) we KNOW that Earth has suffered extinction level collisions while there's been life on the planet. (...which is why they caused extinctions, Sriad.)

[Grey Eminence]

However, the microbes would still have to have evolved on the world they originally came from, and they have a shelf-life of a some tens of millions of years (the suspected age of some revived bacterial cultures recovered on Earth from amber-entombed insects, cavities in rocks and the like.)...

The 'shelf life' for microorganisms is in excess of 100 million years, at least in some cases. The +100 million year old samples were cultured from halite deposits from the US midwest. After providing them a decent environment the microorganisms came back to life quite readily.

[SirNitram]

Could very simple life have actually evolved on comets? We have evidence, after all, of bacteria surviving in climates--such as near volcanic vents, and even inside of rock--which are at least as harsh and possibly more extreme in the former case than deep space.

Remember, there's a point where 'life' and 'chemistry' blur the lines. It could happen in alot of enviroments.

Crazier still is some readings which suggest the presense of sugars in a Nebula; that's not life in comets, that some form of life in a matter cloud in interstellar space. Not complex life, but.

If life can begin in those conditions, when did those conditions first show up? The universe has existed much longer than Earth; if life began popping up in the void early and began riding comets and 'roids down to those pretty rocks where it could make the journey towards multicellular existance, we might be alot less alone than we thought.

Or I'm just insane.

[wolveraptor]

Well, yes. Though material transfer between Mars and Earth is much easier to accomplish. But if Martian bacteria were found to use the same basic biochemistry that our own do, then that would be a pretty strong indicator that life here might've come from there. (Not so much vice-versa, it takes a lot more energy to kick an Earth rock out to Mars, instead of bringing a Mars rock here.)

That's assuming we find any living bacteria on Mars. If everything's dead, you can't really tell what former life's biochemistry was like. DNA doesn't really fossilize.

[Ariphaos]

That's assuming we find any living bacteria on Mars. If everything's dead, you can't really tell what former life's biochemistry was like. DNA doesn't really fossilize.

It leaves chemical signatures, and the structure of the bacterium (or whatever) can also be inferred. It's not perfect, but this sort of evidence has been used to provide evidence of an RNA world on Earth before DNA came to be.

[tharkûn]

Crazier still is some readings which suggest the presense of sugars in a Nebula; that's not life in comets, that some form of life in a matter cloud in interstellar space. Not complex life, but.

Not really sugar can be made by abiotic chemical reactions, particularly the glycoaldehyde found in the nebula (it can be made from reaction between carbon dioxide, methane, and large shockwaves from stellar events among many pathways). These molecules are still achiral which prohibits them being life, at least such as we know it. Also given the temperatures at which they exist (as low as 6 K) I don't see anything doing much metabolism, reproduction, etc.

If life can begin in those conditions, when did those conditions first show up?

Possibly with the first round of star formation/extinction, you will get a small amount of oxygen out away from the star, but conditions would be much more favourable in subsequent rounds.

The universe has existed much longer than Earth; if life began popping up in the void early and began riding comets and 'roids down to those pretty rocks where it could make the journey towards multicellular existance, we might be alot less alone than we thought.

You are still looking at a bit of sweet spot chemistry here. Too close to the star and the shockwave will be too strong and will shread any organized compound, too far away and the energy won't be there to build up at all. After that you have to gather the stuff onto a rock in such a manner that it can survive re-entry and then you have to hit after the planet is sufficiently cooled that it won't break up the sugars or whatever else forms during re-entry and impact.

Given present evidence, the amount, strength, and type of sugar is not encouraging. This doesn't look terribly more likely than terrestrial sugar formation, at present. Of course new evidence keeps coming in and I've already lost one bet on the matter.

That's assuming we find any living bacteria on Mars. If everything's dead, you can't really tell what former life's biochemistry was like. DNA doesn't really fossilize.

If Martian life seeded life on earth then there will be chemicals with uniform chirality left over (unless life was exceedingly rare on mars and all chemical products were obliterated by very hot reactions). Life may not need to be chiral, but terrestrial life does. Any number of minerals will nucleate around biomolecules and those will show chirality when they otherwise wouldn't.

[SirNitram]

Crazier still is some readings which suggest the presense of sugars in a Nebula; that's not life in comets, that some form of life in a matter cloud in interstellar space. Not complex life, but.

Not really sugar can be made by abiotic chemical reactions, particularly the glycoaldehyde found in the nebula (it can be made from reaction between carbon dioxide, methane, and large shockwaves from stellar events among many pathways). These molecules are still achiral which prohibits them being life, at least such as we know it. Also given the temperatures at which they exist (as low as 6 K) I don't see anything doing much metabolism, reproduction, etc.

The temperature is the killer, really, but aren't some Nebula sufficiently dense and close to newborn stars to be warmer?

If life can begin in those conditions, when did those conditions first show up?

Possibly with the first round of star formation/extinction, you will get a small amount of oxygen out away from the star, but conditions would be much more favourable in subsequent rounds.

Still, that increases the number of years for potential life by billions of years, and all it really takes is one lucky instance when the metaphorical dice are always rolling.

But it couldn't have happened any earlier than after the first go, I suppose. Not enough heavier elements.

The universe has existed much longer than Earth; if life began popping up in the void early and began riding comets and 'roids down to those pretty rocks where it could make the journey towards multicellular existance, we might be alot less alone than we thought.

You are still looking at a bit of sweet spot chemistry here. Too close to the star and the shockwave will be too strong and will shread any organized compound, too far away and the energy won't be there to build up at all. After that you have to gather the stuff onto a rock in such a manner that it can survive re-entry and then you have to hit after the planet is sufficiently cooled that it won't break up the sugars or whatever else forms during re-entry and impact.

Oh, the probabilities against it are astronomical. The point is mostly that, if the conditions for the simplest forms of life can form in open space, comets, 'roids, or nebula, you've just massively increased the number of times that incredibly unlikely event could happen. More rolls of the dice, as it were. Yes, re-entry introduces whole new problems which must endure the dice, but a universe teaming with life has alot of rocks, and alot of chances.

Given present evidence, the amount, strength, and type of sugar is not encouraging. This doesn't look terribly more likely than terrestrial sugar formation, at present. Of course new evidence keeps coming in and I've already lost one bet on the matter.

Oh, it's all very 'maybe' and 'what if' at this point. It's of far more use to sci-fi writers than anyone trying to answer 'are we alone'. But it's certainly an interesting twist on panspermia.

And now, because tradition demands it:

There are those who think that life down here, began out there..

Cue intro music!

[LadyTevar]

*facepalm* I wondered when someone would bring up the oBSG and "Chariot of the Gods" references. Bad Nitram! No Cuddles!


On topic, there was a show on History Channel this week: "Meteors". It discussed panspermia as well as the "Martian Meteor" found in Antartica.

[tharkûn]

The temperature is the killer, really, but aren't some Nebula sufficiently dense and close to newborn stars to be warmer?

They are warmer because they are being bathed in high doses of short wavelength EM. Close enough to be warm tends to also be close enough to have UV and up start breaking bonds. Even if you hit the Goldilocks spot for temperature you still have to deal with the lack of external pressure and the lack of a liquid state.

Still, that increases the number of years for potential life by billions of years, and all it really takes is one lucky instance when the metaphorical dice are always rolling.

Possibly, the question of how much chance one is going to get out is going to be dependent on carbon and oxygen concentrations (and too much oxygen is a decidely bad thing here) and for the early stuff it looks like negligable (and I do mean negligable) odds. Remember though the sugars we've detected to date are only useful towards building life as we know it when reacted with other sugars, which we have not yet observed out there.

Oh, the probabilities against it are astronomical. The point is mostly that, if the conditions for the simplest forms of life can form in open space, comets, 'roids, or nebula, you've just massively increased the number of times that incredibly unlikely event could happen. More rolls of the dice, as it were. Yes, re-entry introduces whole new problems which must endure the dice, but a universe teaming with life has alot of rocks, and alot of chances.

And still begs the question of why no one else went colonizing in the intervening years. Definately a theory to look into, but not the one to bet the farm on.

Oh, it's all very 'maybe' and 'what if' at this point. It's of far more use to sci-fi writers than anyone trying to answer 'are we alone'. But it's certainly an interesting twist on panspermia.

Ah. It is legitimate science, but like most legitimate thoeries I don't expect it to pan out.