10 ms·

The idea that life on Earth originated elsewhere is not as far out as it seems

50 points by the-mitr 4y ago

college_physics 4y ago
"The idea of life on Earth" is already so far out that the mere possibility of it having originated elsewhere actually makes it a more plausible occurrence
- implements 4y ago
  Perhaps there’s an emotional tension between those people who would prefer life having a single creator, and those who prefer life as ‘just’ a common consequence of physics -> chemistry -> organic chemistry, etc?
  - college_physics 4y ago
    Tensions can sometimes be productive (in the dialectic sense) but I am not sure this applies to the origin of life question.
miniwark 4y ago
The fun part about the panspermia theory is that it's a very old idea first proposed by Anaxagoras (c. 500 – c. 428 BC), a pre-Socratic Greek philosopher. He had also imagined the concept of a "Cosmic mind" (Nous). If i understand well, for him, this "Cosmic mind" is not really an external metaphysical god, but more a physical part of the universe itself. A mind inside the universe, but isolated from the rest, and who try to organise everything else in the universe (including life).
- college_physics 4y ago
  Most probably such ideas were propagated in oral traditions and embedded in religious thinking ever since homo sapiens got their brain activated. Removing anthropocentric exceptionalism has been a major driver of what we (now) call scientific thought but it is really just a "state of mind" that precedes more sophisticated, culture contingent, frameworks. Ofcourse there is a major difference between betting that "X is not different that all the Y's" and actually proving it :-), which is what makes this field of inquiry so fascinating.
stelliosk 4y ago
https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Where_life_began# https://www.esa.int/Science_Exploration/Space_Science/Rosett... "However, there is now direct evidence that some of the so-called chemical ‘building blocks’ of life – organic molecules – can be found in comets."
TheRealNGenius 4y ago
[dead]
sudhirj 4y ago
If we stop looking at life as some great mystical thing, and look at it as a more mechanical expression of self replicating molecules, it’s quite likely to be all over the place. Even “intelligence” doesn’t seem to be that uncommon, even here on earth. Enough intelligence to look outside and leave a planet may be rarer, given that only one species has it on earth - the dinosaurs were around for longer than humans, but why didn’t they develop enough intelligence and capability to do what we did?
- ant6n 4y ago
  > the dinosaurs were around for longer than humans, but why didn’t they develop enough intelligence and capability to do what we did? How can you be sure they didn’t?
  - f6v 4y ago
    Try to tie a tie or drink from a Starbucks cup with those tiny Trex arms. Ok, maybe they used straws…
    - ant6n 4y ago
      That's like saying that humans couldn't have gone to space because a Mammoth didn't have hands.
- simiones 4y ago
  > If we stop looking at life as some great mystical thing, and look at it as a more mechanical expression of self replicating molecules, it’s quite likely to be all over the place. Well, where we looked, we haven't found it yet, so "all over the place" seems to be an exaggeration. At least it's not on the Moon, and not in any of our landing places on Mars.
- andsoitis 4y ago
  self-consciousness
- hutzlibu 4y ago
plutonorm 4y ago
I've been mocked for decades for supporting this theory. Just like my opinions on AI. Quietly waiting for you guys to level up.
- Pompidou 4y ago
  Decades of "support", or decades of scientific experimentations and thoerisation? I would be glad to read your publications.
  - plutonorm 4y ago
    I can't wait for AGI, I might finally have someone intelligent to talk to.
- astrange 4y ago
  Why is not-Earth better at inventing life than Earth would be? (One reason is there's a lot more of not-Earth than Earth in the universe, but it's all pretty inhospitable.)
  - HarHarVeryFunny 4y ago
    Right, and what are the chances that a life-bearing chunk of a planet from a remote star system happens to crash into earth almost immediately after it's been formed? Seems like a (literal) long-shot to say the least! Pretty interesting kind of life too - able to survive in outer space for inter-stellar travel durations, able to withstand the scorching heat of ripping through earths atmosphere, then able to escape from a chunk of rock to populate the planet. That's more than pan-sperm, that's super-sperm!
zokier 4y ago
Sure panspermia is cute idea, but occams razor cuts it; its simply more complex theory that life first originated somewhere else and then migrated to earth than just that life originated on earth. Unless there are some very compelling explanations why some other place would be so much more favourable environment for originating life?
- localplume 4y ago
  [dead]
- Loquebantur 4y ago
  Yours is a misapplication of Occam's razor. While simpler explanations are preferable, they have to explain the available data. Material is exchanged between planets, bacteria could survive such exchanges. So the possibility exists. People finding that uncomfortable is scientifically irrelevant.
  - xeyownt 4y ago
    How is restricting apparition of life on Earth only not explaining the available data? Assuming transport just add another hypothesis. EDIT: Also, if there was transport, they need to explain why we don't find life on the Moon. So the burden of explanation is more on that theory.
    - _a_a_a_ 4y ago
      Transport through an incredibly brutal medium over an extremely long period. "Far from being rigid and fragile" - you can't make that claim without defining what 'fragile' WRT to which specific conditions. It's sloppy.
  - zokier 4y ago
    First of all panspermia needs evidence of life outside earth, which we so far are still sorely missing. Even if we found such data then it still doubtful if panspermia is any more likely than independent abiogenesis, considering that the mechanics of abiogenesis are still unknown. Only if we found a location that would provide simpler explanation for abiogenesis than on earth then panspermia as a theory would really be viable.
bmitc 4y ago
To me, it seems unlikely because, as far as I understand, life immediately began as soon as Earth cooled. So life is just barely younger than the Earth by only tens to hundreds millions of years. Also, it seems hard to imagine a better place for life to emerge than Earth. I can't watch the video right now, but what are the theories of how life got onto meteors in the first place?
- sampo 4y ago
  > To me, it seems unlikely because, as far as I understand, life immediately began as soon as Earth cooled. Yes. If life originated from panspermia, and right after the planet had cooled down, that would imply that there should be a more or less continuous bombardment of panspermic seeds from the universe. If so, we should be receiving these seeds also now, and we should then be able to detect them.
  - mschuster91 4y ago
    > If so, we should be receiving these seeds also now, and we should then be able to detect them. Actually, we are - precursors to stuff like RNA have been found in comets and meteorites [1]. [1] https://theconversation.com/did-comets-kick-start-life-on-earth-chemists-find-missing-piece-of-puzzle-57369 https://theconversation.com/did-comets-kick-start-life-on-ea...
    - funcDropShadow 4y ago
      But precursors to RNA have a also spontaneously emerged in experiments resembling the early earth.
      - Ancapistani 4y ago
        ... and we have no idea how things went from "RNA precursors" to "independent reproduction". All extant RNA-based organisms require host DNA to reproduce. I see no reason to believe that RNA came first.
  - 4y ago
dvh 4y ago
We are exceptionally close to big bang, only 2 sun's lifetimes from it and life is on earth for maybe half that, IMHO there is not much time for panspermia, 30-50 Gy in the future sure, but now? It seems too soon.
entropyneur 4y ago
The problem with panspermia, simulation hypothesis and the like, aside from Occam's razor violation, is that instead of proposing an answer they just declare it effectively unknowable. An interesting panspermia hypothesis would include a description of the place where life originated instead of Earth and the process by which it emerged.
- Loquebantur 4y ago
  There is nothing in the idea of panspermia that would render knowing the origin of life on a given planet unknowable in principle. It simply concerns itself with investigating the possibility and as such is a scientific necessity even. Actually, just ignoring that possibility is what would be unscientific, as it would comprise unfounded bias. Besides, the video considers life from earth having spread to other planets first, with the reverse a less likely possibility.
- QuadmasterXLII 4y ago
  A toy hypothesis: if we find the planet where life originated, it might be dominated by ribosome-based life but with a few RNA-only species surviving.
  - Ancapistani 4y ago
    https://en.wikipedia.org/wiki/RNA_world https://en.wikipedia.org/wiki/RNA_world Too bad we're not aware of any RNA-based life that can reproduce without access to DNA.
- thro1 4y ago
  Isn't enough that some of our rubbish at some far time land finally in some place where aminoacids form byself already et voila ? (they call themselves Eaerthians, too..)
  - thro1 4y ago
    Rethinking. Quite possibly the emergence of life as we know it, in the whole universe happened once only. That was extremally improbable, the forms was fragile, unimaginable but not ugly, and a lot, lot lot of lucky events must have happen for it.. but finaly it was conscious, had a look at itself, own limits and improbability of this happening even again.. even in all the infinity of space and time.. Once was enough. It existed long enough only to - after exhausting study - re-engineer its own formula according to conditions and laws of ethernity and choosed the best - small fractal twist of a carbon based spiral was the minimal requirement supporting all the casess of: in minimal conditions being emergent, viral and unstoppable. Eternal. Life.. may be common in space, uncommon in time. (AI, as we know it, is dead not inert; as we don't know it, may be part ot that fractal twist..)
too_much_churn 4y ago
What scientific problem would actually be solved by panspermia? Obviously, the product of two unlikely events is not more likely than one unlikely event by itself. Not to mention, we have zero evidence that comets can really seed life and we also have absolutely no reason to believe that any place in the universe is better at spawning life than earth. So I wonder, why is this idea so attractive?
- Ancapistani 4y ago
  > we have zero evidence that comets can really seed life I would argue that this isn't precisely true. We know of some forms of relatively complex terrestrial life that can survive for indefinite (as far as we know) periods in vacuum - tardigrades are the most common example given. For some other good candidates, I'd start with the list included the (failed) LIFE mission: https://en.wikipedia.org/wiki/Living_Interplanetary_Flight_Experiment https://en.wikipedia.org/wiki/Living_Interplanetary_Flight_E... > What scientific problem would actually be solved by panspermia? Obviously, the product of two unlikely events is not more likely than one unlikely event by itself. Panspermia is the belief that life is pervasive across the Universe. You don't have to believe that to believe that terrestrial life may not have originated here. From a statistically perspective, if we assume that life has arisen exactly once, it's no less likely that it arose on Mars as on Earth. Maybe some or all of the early history of life had already happened before the accretion of Earth. If that's the case, we'll likely never find direct evidence of it. In short... I'd argue that panspermia doesn't "solve" any problems at all. If life is unique to Earth, we should be able to find evidence of its earliest forms. If it originated on Mars and was "seeded" here, then we should eventually find that evidence there. If it's universal, it still had to have originated _somewhere_; it's just going to be much more difficult to discover where. To the best of my (lay) understanding, while we have a fair idea of how life might have began, we don't have very good evidence that it actually began on Earth. What we do know: * Earth is ~4.5b years old. * The oldest fossils we know of are ~3.5b years old: https://news.wisc.edu/oldest-fossils-found-show-life-began-before-3-5-billion-years-ago/ https://news.wisc.edu/oldest-fossils-found-show-life-began-b... * There exists evidence suggestive of life that is ~3.8b years old, in the form of what we believe to be precipitate from a oceanic hydrothermal vent that shows signatures of biological processes. This means that in order for life to have arisen on Earth, it must have done so in the first ~1b years - because those oldest fossils mentioned above included multicellular life. To go from "primordial soup" to "multicellular microorganisms" is a pretty big leap, and we don't know the specifics. Then there's the fact that _all_ known life either contains DNA or, in the case of RNA viruses, requires access to DNA-based life to reproduce. We don't know what came before that. Did primitive metabolism in come first, or genes (encoding structure in a durable and reproducible way)? Did they arise in tandem? Either way, we are very confident that 1b years after the matter that we now know as Earth coalesced, there were multicellular organisms alive. Since all known life requires DNA, that means DNA was around at that point as well. That doesn't seem long enough to me, and apparently others share that intuition. (edited for coherence)
mcqueenjordan 4y ago
I didn't think this idea was all that far out there in the first place, was it?
wslh 4y ago
I wonder why Occam's razor is wrongly used in many of this thread comments as a rule instead of an heuristic for simplicity. Violating the Occam's razor is not a logic absurd. This is not in favor or against of the article proposal, just an issue with using logical arguments.
Idiot_in_Vain 4y ago
The simplest known forms of life - simple bacteria and archea are extremely complex. They have hundreds of different proteins, RNA, DNA, membranes, interacting in a million different ways. Humankind has been able to create multi-gigahertz processors, H bombs, complicated software systems, but not artificial living being from scratch. It looks like there were bacteria on Earth just a few hundred million years after the planet formed a solid surface. On other hand next major steps in evolution - like eucariots and multi-cellurality took billions of years. Either early life evolution was extremely fast or life originated elsewhere and had much more time to evolve into bacteria and archea. One panspermia hypothesis is life originated on Mars. It has a lot of iron, and iron catalysis a lot of the chemical reactions that probably made early life. Mars formed a solid surface about a billion years earlier than Earth. Also early on it had a magnetic field, that could protect a thicker athmosphere, that would allow for the existance of seas and oceans. So potentially life originated on Mars, took a billion years to evolve into bacteria/archea, which made the jorney to earth on pieces of rock, displaced by an asteroid impact (a lot of Marsian rocks fall down on Earth).
Pigalowda 4y ago
Fun video. The bulk of engagement in the comments appears to be contrarians who didn’t bother watching.
prirun 4y ago
I loved this theme in the movie Prometheus.
HarHarVeryFunny 4y ago
Tough to rule it out I suppose, and would be interesting to know purely as a matter of history, but I really don't see the attraction of it as an idea in of itself. The emergence of primitive proto-cells, then unicellular life, whereever it originated, seems quite easy to understand, and I'd agree with Stuart Kaufmann's "At home in the universe" suggestion that it appears more inevitable given a few environmental prerequisites than something requiring an extraordinary explanation. If interstellar RNA(?) did find it's way to earth, then it was likely competing with home-grown primitive cells, given what we know about early earth conditions and the inevitable rise of complexity. The basic idea is that all it took for life/evolution to get started was a circular chain of chemical reactions (a primitive/proto-metabolism - consuming environment chemicals, and producing others) and some type of semi-permeable container (eventually to become a cell wall) such as a fatty bubble made out of hydrocarbons that can be produced in early-earth conditions. That's all evolution would have needed to get started - some froth on the seashore (or by the deep sea vent/whereever) "competing" with other flavors of froth for numerical supremacy. The more interesting phases of evolution, which it seems are less inevitable (or perhaps I should say lower probability - but nonetheless inevitable given enough time) are things like the emergence of multi-cellular life, or what triggered the "Cambrian explosion" of variety to emerge.
- matt-attack 4y ago
  Is the formation of DNA from the proto cells you’re describing, not still a pretty big mystery?
  - HarHarVeryFunny 4y ago
    Well, that obviously would have been something that evolved too, from simple beginnings. The progression must have from proto-cells that formed and replicated due to general environmental factors (prevailing chemicals/polymers, wave/thermal agitation, etc), to ones that eventually did so progressively more due to their individual chemistry, to varying degrees of success. Any aspect of the chemistry of a particular "colony" of proto-cells that played a role in helping create/preserve the chemical contents and structure of these proto-cells could be regarded as the earliest precursors of RNA/DNA. For example, if the localized chemistry generated self-serving catalysts, or transformed environmental chemicals into others that helped stabilize or produce the proto-cell bubble/container, then these become the beginnings of a colony that is self-defining and beginning to differentiate itself - starting to encode it's own structure. For sure there's a long ways from these types of humble beginning to full blown RNA/DNA, but plenty of scope for the types of incremental improvement that would have driven evolution (better ability to utilize environmental chemicals and energy sources, better ability to survive environmental changes, better ability to replicate and disperse, etc, etc.).
euroderf 4y ago
Adjacent to Terrance McKenna's ideas about spores from space.

50 points by the-mitr 4y ago

"The idea of life on Earth" is already so far out that the mere possibility of it having originated elsewhere actually makes it a more plausible occurrence

implements 4y ago
Perhaps there’s an emotional tension between those people who would prefer life having a single creator, and those who prefer life as ‘just’ a common consequence of physics -> chemistry -> organic chemistry, etc?
- college_physics 4y ago
  Tensions can sometimes be productive (in the dialectic sense) but I am not sure this applies to the origin of life question.

miniwark 4y ago

The fun part about the panspermia theory is that it's a very old idea first proposed by Anaxagoras (c. 500 – c. 428 BC), a pre-Socratic Greek philosopher. He had also imagined the concept of a "Cosmic mind" (Nous). If i understand well, for him, this "Cosmic mind" is not really an external metaphysical god, but more a physical part of the universe itself. A mind inside the universe, but isolated from the rest, and who try to organise everything else in the universe (including life).

college_physics 4y ago
Most probably such ideas were propagated in oral traditions and embedded in religious thinking ever since homo sapiens got their brain activated. Removing anthropocentric exceptionalism has been a major driver of what we (now) call scientific thought but it is really just a "state of mind" that precedes more sophisticated, culture contingent, frameworks. Ofcourse there is a major difference between betting that "X is not different that all the Y's" and actually proving it :-), which is what makes this field of inquiry so fascinating.

stelliosk 4y ago

https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Where_life_began# https://www.esa.int/Science_Exploration/Space_Science/Rosett... "However, there is now direct evidence that some of the so-called chemical ‘building blocks’ of life – organic molecules – can be found in comets."

TheRealNGenius 4y ago

[dead]

sudhirj 4y ago

If we stop looking at life as some great mystical thing, and look at it as a more mechanical expression of self replicating molecules, it’s quite likely to be all over the place. Even “intelligence” doesn’t seem to be that uncommon, even here on earth. Enough intelligence to look outside and leave a planet may be rarer, given that only one species has it on earth - the dinosaurs were around for longer than humans, but why didn’t they develop enough intelligence and capability to do what we did?

ant6n 4y ago
> the dinosaurs were around for longer than humans, but why didn’t they develop enough intelligence and capability to do what we did? How can you be sure they didn’t?
- f6v 4y ago
  Try to tie a tie or drink from a Starbucks cup with those tiny Trex arms. Ok, maybe they used straws…
  - ant6n 4y ago
    That's like saying that humans couldn't have gone to space because a Mammoth didn't have hands.
simiones 4y ago
> If we stop looking at life as some great mystical thing, and look at it as a more mechanical expression of self replicating molecules, it’s quite likely to be all over the place. Well, where we looked, we haven't found it yet, so "all over the place" seems to be an exaggeration. At least it's not on the Moon, and not in any of our landing places on Mars.
andsoitis 4y ago
self-consciousness
hutzlibu 4y ago

plutonorm 4y ago

I've been mocked for decades for supporting this theory. Just like my opinions on AI. Quietly waiting for you guys to level up.

Pompidou 4y ago
Decades of "support", or decades of scientific experimentations and thoerisation? I would be glad to read your publications.
- plutonorm 4y ago
  I can't wait for AGI, I might finally have someone intelligent to talk to.
astrange 4y ago
Why is not-Earth better at inventing life than Earth would be? (One reason is there's a lot more of not-Earth than Earth in the universe, but it's all pretty inhospitable.)
- HarHarVeryFunny 4y ago
  Right, and what are the chances that a life-bearing chunk of a planet from a remote star system happens to crash into earth almost immediately after it's been formed? Seems like a (literal) long-shot to say the least! Pretty interesting kind of life too - able to survive in outer space for inter-stellar travel durations, able to withstand the scorching heat of ripping through earths atmosphere, then able to escape from a chunk of rock to populate the planet. That's more than pan-sperm, that's super-sperm!

zokier 4y ago

Sure panspermia is cute idea, but occams razor cuts it; its simply more complex theory that life first originated somewhere else and then migrated to earth than just that life originated on earth. Unless there are some very compelling explanations why some other place would be so much more favourable environment for originating life?

localplume 4y ago
[dead]
Loquebantur 4y ago
Yours is a misapplication of Occam's razor. While simpler explanations are preferable, they have to explain the available data. Material is exchanged between planets, bacteria could survive such exchanges. So the possibility exists. People finding that uncomfortable is scientifically irrelevant.
- xeyownt 4y ago
  How is restricting apparition of life on Earth only not explaining the available data? Assuming transport just add another hypothesis. EDIT: Also, if there was transport, they need to explain why we don't find life on the Moon. So the burden of explanation is more on that theory.
  - _a_a_a_ 4y ago
    Transport through an incredibly brutal medium over an extremely long period. "Far from being rigid and fragile" - you can't make that claim without defining what 'fragile' WRT to which specific conditions. It's sloppy.
- zokier 4y ago
  First of all panspermia needs evidence of life outside earth, which we so far are still sorely missing. Even if we found such data then it still doubtful if panspermia is any more likely than independent abiogenesis, considering that the mechanics of abiogenesis are still unknown. Only if we found a location that would provide simpler explanation for abiogenesis than on earth then panspermia as a theory would really be viable.

bmitc 4y ago

To me, it seems unlikely because, as far as I understand, life immediately began as soon as Earth cooled. So life is just barely younger than the Earth by only tens to hundreds millions of years. Also, it seems hard to imagine a better place for life to emerge than Earth. I can't watch the video right now, but what are the theories of how life got onto meteors in the first place?

sampo 4y ago
> To me, it seems unlikely because, as far as I understand, life immediately began as soon as Earth cooled. Yes. If life originated from panspermia, and right after the planet had cooled down, that would imply that there should be a more or less continuous bombardment of panspermic seeds from the universe. If so, we should be receiving these seeds also now, and we should then be able to detect them.
- mschuster91 4y ago
  > If so, we should be receiving these seeds also now, and we should then be able to detect them. Actually, we are - precursors to stuff like RNA have been found in comets and meteorites [1]. [1] https://theconversation.com/did-comets-kick-start-life-on-earth-chemists-find-missing-piece-of-puzzle-57369 https://theconversation.com/did-comets-kick-start-life-on-ea...
  - funcDropShadow 4y ago
    But precursors to RNA have a also spontaneously emerged in experiments resembling the early earth.
    - Ancapistani 4y ago
      ... and we have no idea how things went from "RNA precursors" to "independent reproduction". All extant RNA-based organisms require host DNA to reproduce. I see no reason to believe that RNA came first.
- 4y ago

dvh 4y ago

We are exceptionally close to big bang, only 2 sun's lifetimes from it and life is on earth for maybe half that, IMHO there is not much time for panspermia, 30-50 Gy in the future sure, but now? It seems too soon.

entropyneur 4y ago

The problem with panspermia, simulation hypothesis and the like, aside from Occam's razor violation, is that instead of proposing an answer they just declare it effectively unknowable. An interesting panspermia hypothesis would include a description of the place where life originated instead of Earth and the process by which it emerged.

Loquebantur 4y ago
There is nothing in the idea of panspermia that would render knowing the origin of life on a given planet unknowable in principle. It simply concerns itself with investigating the possibility and as such is a scientific necessity even. Actually, just ignoring that possibility is what would be unscientific, as it would comprise unfounded bias. Besides, the video considers life from earth having spread to other planets first, with the reverse a less likely possibility.
QuadmasterXLII 4y ago
A toy hypothesis: if we find the planet where life originated, it might be dominated by ribosome-based life but with a few RNA-only species surviving.
- Ancapistani 4y ago
  https://en.wikipedia.org/wiki/RNA_world https://en.wikipedia.org/wiki/RNA_world Too bad we're not aware of any RNA-based life that can reproduce without access to DNA.
thro1 4y ago
Isn't enough that some of our rubbish at some far time land finally in some place where aminoacids form byself already et voila ? (they call themselves Eaerthians, too..)
- thro1 4y ago
  Rethinking. Quite possibly the emergence of life as we know it, in the whole universe happened once only. That was extremally improbable, the forms was fragile, unimaginable but not ugly, and a lot, lot lot of lucky events must have happen for it.. but finaly it was conscious, had a look at itself, own limits and improbability of this happening even again.. even in all the infinity of space and time.. Once was enough. It existed long enough only to - after exhausting study - re-engineer its own formula according to conditions and laws of ethernity and choosed the best - small fractal twist of a carbon based spiral was the minimal requirement supporting all the casess of: in minimal conditions being emergent, viral and unstoppable. Eternal. Life.. may be common in space, uncommon in time. (AI, as we know it, is dead not inert; as we don't know it, may be part ot that fractal twist..)

too_much_churn 4y ago

What scientific problem would actually be solved by panspermia? Obviously, the product of two unlikely events is not more likely than one unlikely event by itself. Not to mention, we have zero evidence that comets can really seed life and we also have absolutely no reason to believe that any place in the universe is better at spawning life than earth. So I wonder, why is this idea so attractive?

Ancapistani 4y ago
> we have zero evidence that comets can really seed life I would argue that this isn't precisely true. We know of some forms of relatively complex terrestrial life that can survive for indefinite (as far as we know) periods in vacuum - tardigrades are the most common example given. For some other good candidates, I'd start with the list included the (failed) LIFE mission: https://en.wikipedia.org/wiki/Living_Interplanetary_Flight_Experiment https://en.wikipedia.org/wiki/Living_Interplanetary_Flight_E... > What scientific problem would actually be solved by panspermia? Obviously, the product of two unlikely events is not more likely than one unlikely event by itself. Panspermia is the belief that life is pervasive across the Universe. You don't have to believe that to believe that terrestrial life may not have originated here. From a statistically perspective, if we assume that life has arisen exactly once, it's no less likely that it arose on Mars as on Earth. Maybe some or all of the early history of life had already happened before the accretion of Earth. If that's the case, we'll likely never find direct evidence of it. In short... I'd argue that panspermia doesn't "solve" any problems at all. If life is unique to Earth, we should be able to find evidence of its earliest forms. If it originated on Mars and was "seeded" here, then we should eventually find that evidence there. If it's universal, it still had to have originated _somewhere_; it's just going to be much more difficult to discover where. To the best of my (lay) understanding, while we have a fair idea of how life might have began, we don't have very good evidence that it actually began on Earth. What we do know: * Earth is ~4.5b years old. * The oldest fossils we know of are ~3.5b years old: https://news.wisc.edu/oldest-fossils-found-show-life-began-before-3-5-billion-years-ago/ https://news.wisc.edu/oldest-fossils-found-show-life-began-b... * There exists evidence suggestive of life that is ~3.8b years old, in the form of what we believe to be precipitate from a oceanic hydrothermal vent that shows signatures of biological processes. This means that in order for life to have arisen on Earth, it must have done so in the first ~1b years - because those oldest fossils mentioned above included multicellular life. To go from "primordial soup" to "multicellular microorganisms" is a pretty big leap, and we don't know the specifics. Then there's the fact that _all_ known life either contains DNA or, in the case of RNA viruses, requires access to DNA-based life to reproduce. We don't know what came before that. Did primitive metabolism in come first, or genes (encoding structure in a durable and reproducible way)? Did they arise in tandem? Either way, we are very confident that 1b years after the matter that we now know as Earth coalesced, there were multicellular organisms alive. Since all known life requires DNA, that means DNA was around at that point as well. That doesn't seem long enough to me, and apparently others share that intuition. (edited for coherence)

mcqueenjordan 4y ago

I didn't think this idea was all that far out there in the first place, was it?

wslh 4y ago

I wonder why Occam's razor is wrongly used in many of this thread comments as a rule instead of an heuristic for simplicity. Violating the Occam's razor is not a logic absurd. This is not in favor or against of the article proposal, just an issue with using logical arguments.

Idiot_in_Vain 4y ago

The simplest known forms of life - simple bacteria and archea are extremely complex. They have hundreds of different proteins, RNA, DNA, membranes, interacting in a million different ways. Humankind has been able to create multi-gigahertz processors, H bombs, complicated software systems, but not artificial living being from scratch. It looks like there were bacteria on Earth just a few hundred million years after the planet formed a solid surface. On other hand next major steps in evolution - like eucariots and multi-cellurality took billions of years. Either early life evolution was extremely fast or life originated elsewhere and had much more time to evolve into bacteria and archea. One panspermia hypothesis is life originated on Mars. It has a lot of iron, and iron catalysis a lot of the chemical reactions that probably made early life. Mars formed a solid surface about a billion years earlier than Earth. Also early on it had a magnetic field, that could protect a thicker athmosphere, that would allow for the existance of seas and oceans. So potentially life originated on Mars, took a billion years to evolve into bacteria/archea, which made the jorney to earth on pieces of rock, displaced by an asteroid impact (a lot of Marsian rocks fall down on Earth).

Pigalowda 4y ago

Fun video. The bulk of engagement in the comments appears to be contrarians who didn’t bother watching.

prirun 4y ago

I loved this theme in the movie Prometheus.

HarHarVeryFunny 4y ago

Tough to rule it out I suppose, and would be interesting to know purely as a matter of history, but I really don't see the attraction of it as an idea in of itself. The emergence of primitive proto-cells, then unicellular life, whereever it originated, seems quite easy to understand, and I'd agree with Stuart Kaufmann's "At home in the universe" suggestion that it appears more inevitable given a few environmental prerequisites than something requiring an extraordinary explanation. If interstellar RNA(?) did find it's way to earth, then it was likely competing with home-grown primitive cells, given what we know about early earth conditions and the inevitable rise of complexity. The basic idea is that all it took for life/evolution to get started was a circular chain of chemical reactions (a primitive/proto-metabolism - consuming environment chemicals, and producing others) and some type of semi-permeable container (eventually to become a cell wall) such as a fatty bubble made out of hydrocarbons that can be produced in early-earth conditions. That's all evolution would have needed to get started - some froth on the seashore (or by the deep sea vent/whereever) "competing" with other flavors of froth for numerical supremacy. The more interesting phases of evolution, which it seems are less inevitable (or perhaps I should say lower probability - but nonetheless inevitable given enough time) are things like the emergence of multi-cellular life, or what triggered the "Cambrian explosion" of variety to emerge.

matt-attack 4y ago
Is the formation of DNA from the proto cells you’re describing, not still a pretty big mystery?
- HarHarVeryFunny 4y ago
  Well, that obviously would have been something that evolved too, from simple beginnings. The progression must have from proto-cells that formed and replicated due to general environmental factors (prevailing chemicals/polymers, wave/thermal agitation, etc), to ones that eventually did so progressively more due to their individual chemistry, to varying degrees of success. Any aspect of the chemistry of a particular "colony" of proto-cells that played a role in helping create/preserve the chemical contents and structure of these proto-cells could be regarded as the earliest precursors of RNA/DNA. For example, if the localized chemistry generated self-serving catalysts, or transformed environmental chemicals into others that helped stabilize or produce the proto-cell bubble/container, then these become the beginnings of a colony that is self-defining and beginning to differentiate itself - starting to encode it's own structure. For sure there's a long ways from these types of humble beginning to full blown RNA/DNA, but plenty of scope for the types of incremental improvement that would have driven evolution (better ability to utilize environmental chemicals and energy sources, better ability to survive environmental changes, better ability to replicate and disperse, etc, etc.).

euroderf 4y ago

Adjacent to Terrance McKenna's ideas about spores from space.