
What If Life Did Not Originate on Earth? - laurex
https://www.newyorker.com/news/q-and-a/what-if-life-did-not-originate-on-earth
======
rectangletangle
An interesting phenomenon I rarely see brought up in support of panspermia is
the apparent universality of the genetic code. The fact that all known life
shares a common genetic structure implies a common ancestor. The lack of
competing genetic codes could be interpreted to imply that life only started
on earth once, or that it only made it to earth once. Natural selection is a
constant force, presumably new genetic codes could offer an advantage, e.g.,
robustness against damaging mutation, resulting in multiple competing genetic
codes.

The notion of abiogenesis occurring only once on earth seems improbable
considering complex organs like eyes have evolved independently several
different times. Or the fact that convergent evolution "reinvents" similar
species in response to similar selective pressures. Selective pressures
constantly "push" life in the same directions, so it would seem that whatever
forces gave rise to life would have happened so repeatedly, but there doesn't
seem to be any evidence for that.

A clean explanation for this would be that life didn't start on earth, and
earth may have never had the right conditions to originate life, hence no
competing genetic codes. But it was still hospitable enough to maintain life,
so one universal genetic code flourishes with no emergent competition.

~~~
tsimionescu
Doesn't that just beg the question? If life originated on some other planet
and made it to Earth, why did only the DNA-based lifeform(s) make it here?

If we assume that different kinds of life based on different nucleic acids can
co-exist, then it seems unlikely that a single kind would have happened to be
carried to Earth by a natural process.

If we assume DNA has some inherent fitness advantage (so that only DNA-based
life survived the journey), than we don't need the additional assumption of
panspermia: perhaps only the DNA-based life survived some early period in
Earth's history.

Also, for abiogenesis, given that we still can't reliably reproduce something
like that, and that we have never seen new kinds of life spontaneously
appearing on Earth, we do have some circumstantial evidence for the
possibility that it is an incredibly unlikely event, such that it might have
only happened once in Earth's history.

Edit: There is also another simple possibility: perhaps given the resources
available on Earth, either forever or in the period where abiogenesis was
possible, perhaps DNA(+RNA) is the only molecule with the right properties to
act as genetic material. Perhaps there is no common ancestor to all life on
Earth, but a "forest" of inter-breeding, spotnaneously arisen original
organisms, but they were all DNA/RNA-based simply because of the available
resources.

~~~
csomar
It'll be easier to send a DNA without a life-form. A life-form is very
expensive (need to eat and breath) and not necessarily adaptable to earth
conditions.

A very well encapsulated and protected DNA will land on earth and create the
most adaptable life-form there through mutation and competition. All of these
life-forms have the trait of wanting to pass their genes, multiply as much as
possible and then spread around.

So the engineers probably had that in mind:

1- Extremely small: Probably so that they can propel it through space at very
high speed + propel lots of it.

2- No maintenance required.

3- Will create a life-form if possible that is adaptable to the target
country.

4- The life-form has the property of multiplication, and spreading.

5- The new superior life-form will propel more of these DNA.

~~~
rectangletangle
>A life-form is very expensive (need to eat and breath)

Not necessarily, many organisms can undergo cryptobiosis, where all metabolic
activity ceases, and then restarts when conditions are appropriate (sometimes
decades later).

~~~
andai
Fungi & bacteria can turn into spores & travel through space. There was also
recent article about fungus growing on the outside (!) of the space station.

~~~
rjf72
There are also things like tardigrades [1] which are pretty much the epoch of
survival evolution. And this is all just stuff on our little planet. It's hard
to say anything about life on a large scale, since we are basing everything we
know on a sample of one. But it's probably safe to say that we have not even
scratched the surface of what's possibility through just plain old evolution
alone.

[1] -
[https://en.wikipedia.org/wiki/Tardigrade](https://en.wikipedia.org/wiki/Tardigrade)

~~~
imtringued
There are still a few billion years left for earth to shine.

------
opportune
Methane is not nearly as good a signal to look for life as larger organic
molecules are. Methane can easily be created by abiotic processes and remain
stable when not directly exposed to radiation or oxidizers indefinitely: this
happens on earth, and we do have oxidizers everywhere. Larger organic
molecules are less likely to have abiotic origins by any known process and are
almost always much less stable.

On earth you can test whether methane has organic or abiotic origins by
testing its isotopes. We can do this because we understand decently well how
the geologic past of earth unfolded. We could probably do a similar thing for
mars

>The Earth is 4.5 billion years old. And the universe, at least based on
estimates from the Big Bang, is something like fourteen billion years. So, if
life evolved somewhere else, that buys you about ten billion years of time.

Obviously I'm no expert, but you have to keep in mind, it took a decent amount
of time for non-violent stars to become the norm / stellar neighborhoods to
calm down and for overall metallicity to become significant enough to allow
for the formation of terrestrial planets.

~~~
keyle
Pardon my ignorance, but the Earth is 1/3 the age of the Universe?

~~~
flukus
Yep, time is the universes only dimension the earth is not a tiny and
insignificant blip on, so far anyway.

~~~
keyle
Yeah this exactly. Today my perspective of the universe changed a little.

~~~
mongol
What did you think it's age was?

~~~
flukus
I can't answer for them, but it's completely believable they knew the age of
the earth and the age of the universe in the abstract sense and never really
connected both ludicrously large numbers together. That's why we have tools
like Sagan's squeezing it into a year calendar just so humans can understand
it in relatable terms.

------
derekp7
Even though we have only one datapoint, I wonder how much can be inferred from
this planet's life characteristics.

First, life came about rather shortly after the planet was able to sustain it.
So this timing is either very unlikely, or biogenesis has a high probability
of happening, or the initial life got seeded from off planet (from a very rare
initial phenomenon).

Second, all the biosignatures from all forms of life are similar. For example,
corality (left handed versus right handed molecules) is the same in all life
examples we had. So that means that biogenesis happened only once. Otherwise
we would have multiple unrelated examples (yes, there is the possibility that
one form "ate everything else", but we have all kinds of variety instead of
only one organism becoming dominate). So if biogenesis happened only once (for
all of our bio examples), then it is either a rare event that just happened to
occur very shortly after the planet cooled, or it happened sometime before
Earth was hospitable for life and elsewhere in the universe.

Does any of this make sense? Or am I reading too much into the tea leaves?

~~~
infectoid
Your tea leaves are sound.

I think this is why those of us interested in this are very much hanging out
for results from our explorations of Mars. It's pretty much our only
opportunity to see if life emerged twice in the same planetary system under
similar conditions.

What are the chances?

On the positive side Mars had pretty much all the ingredients for life
(chemically) and had a long enough period for at least _something_ intersting
to develop. On the negative side, the environment was still different to ours
(gravity, climate, whether, etc).

We still aren't clear on what conditions need to met for like to get going.
This is why both positive or negative results on Mars are exciting.

My favourite theory is that life actually takes ages to get started so much so
that it started on Mars and finished on Earth (from Mars being impacted and
debris making it to Earth). Kind of like a passing of the torch.

Mars: "Crap. I'm dying. Hey Earth, can you take this thing I've been working
on?"

Earth: "Yep. No worries. I got this. Will try to send some back in a few
billions years. Take care."

~~~
codesushi42
_> It's pretty much our only opportunity to see if life emerged twice in the
same planetary system under similar conditions._

You mean carbon based life. Methane based life may be a possibility, and you
wouldn't have found it on Mars. You might find it on Titan.

~~~
dredmorbius
Methane is an organic (carbon-chain) molecule: CH4.

Titan would have a low-temperature carbon-based chemistry, but it would remain
carbon-based if focused on methane.

Alternative hypothetical biochemistries usually focus on silicon.

~~~
codesushi42
True. But a methane based lifeform would be radically different than the
carbon based lifeforms found on Earth, and would have emerged separately.

~~~
dredmorbius
Oddly, that wasn't your claim.

~~~
codesushi42
It was. Read the OP's claims about Mars.

Mars alone does not provide the answer about whether or not life evolved
independently in our solar system.

------
apo
The question of where life originated will have no good answer until we figure
out how to create life from basic components. We still don't know how to do
that yet.

Yes, Urey and Miller showed that you could get simple organic molecules by
passing an electric charge through gasses thought to be present around the
early Earth.

But going from low molecular weight inputs to life is a vastly different
problem. You could think of it as the most complicated bootstrapping problem
in the universe.

Nobody has managed to do it in the lab, either. What can't be built from
scratch can't be understood very well, and therein lies the problem.

If we had a stepwise procedure for building a self-replicating, self-feeding
organism of any level of complexity from base components, we would know
exactly what to look for.

Until then, the idea of sending a DNA amplifier to Mars isn't a bad fallback
position.

~~~
dvfjsdhgfv
If we succeed, it would be the most important breakthrough in the history of
humanity, and would have very deep existential implications. It wouldn't
definitely rule out a supreme being as the creator of the universe we live in,
but it would make the gap between us and that being much smaller than millions
of people on earth believe now.

~~~
acqq
> would have very deep existential implications.

I doubt that.

> It wouldn't definitely rule out a supreme being as the creator of the
> universe we live in

Yes, that's exactly what the believers will tell you even then.

Think about it: the science _knows_ today that _every_ atom in our bodies is
either produced 13.8 billion years ago (is it is H2) or in the explosion of
some star. It's true for every element that you learn in the chemistry class.
We know that the Earth is 4.7 billion years old. And we already know that
humans share 99% percent of the DNA with chimps. And that 0.006 billion years
ago on the Earth neither humans nor chimps existed, but their common ancestor.

Do people who believe in a "miracle" divine intervention that supposedly
happened only some 0.000002 billion years ago (or even only 0.0000014 billion
years ago) when only at that point their deity became involved with the
believers, do these people in anyway feel affected by all that? No.

Compared to what we know today, their religious "messages from the deity"
obviously prove that they were written by plain humans of older times, because
these messages don't contain any knowledge we have today, but instead the
"eternal" truths like "at the end of the day the Sun sets in the muddy pond"
or that the Earth's sky is a solid dome:
[https://en.wikipedia.org/wiki/Firmament#Biblical_use](https://en.wikipedia.org/wiki/Firmament#Biblical_use)

Do the believers feel affected by that? No.

------
wahern
> The reason this news registered among scientists is that methane is often a
> sign of life; although the gas can be produced by various chemical
> reactions, most of it comes from animate beings.

This doesn't sound right at all. There are literally lakes of methane on
Titan. The atmospheres of Jupiter, Saturn, Uranus, and Neptune all contain
significant methane--it's what makes Uranus and Neptune blue. Pluto has
methane ice.

IIRC from the original reporting, some recent research suggested that there's
more methane than contemporary geological models of Mars predict. Which likely
says more about the [non-biological] deficiencies in those models than it does
the likelihood of life.

I'm not an astro-anything, so feel free to correct me. But it's telling that
the interviewee never comes close to confirming the reporter's claims; they're
simply quoted as saying, "I think probably many people would like the idea of
methanogens on Mars", and "the idea that they might be related to methanogens
on Earth is not crazy." Isaac Chotiner is a name I'll try to remember so I can
avoid his articles.

~~~
BurningFrog
There is _ancient_ methane in those places. But something on Mars is
_producing_ methane.

Methane breaks down pretty fast in Mars' atmosphere, and yet it reappears
there occasionally. That can certainly have non life explanations. But they're
fairly exotic.

------
mellosouls
Minor fun fact: Fred Hoyle, possibly the most public proponent of Panspermia
in the last few decades, also coined the phrase "Big Bang theory" to dismiss
an alternative to his preferred Steady State theory of the universe.

Sometime champion of arch positions, he was once quoted as saying "it is
better to be interesting and wrong than boring and right".

[https://en.m.wikipedia.org/wiki/Fred_Hoyle](https://en.m.wikipedia.org/wiki/Fred_Hoyle)

~~~
throwaway2048
It is a pretty out there theory, but at one point the universe would have
cooled enough from the very hot big bang origins to allow liquid water to
exist everywhere, but not cooled sufficiently to cause everything to freeze.

If any rocky planets existed at the time, maybe that was the origin of life
which was much more able to spread widely due to the small size of the early
universe.

[https://arxiv.org/abs/1312.0613](https://arxiv.org/abs/1312.0613)

~~~
minitoar
This just sounds like a cool sci-fi setting/backstory.

------
gojomo
The idea life emerged long before Earth, and may be widespread in the
universe, is fairly old:

[https://en.wikipedia.org/wiki/Panspermia](https://en.wikipedia.org/wiki/Panspermia)

I suspect that a formal, anonymous survey of astrobiologists would find that
the idea is far more prevalent among experts than Ruvkin's estimate that "one
per cent would buy into the idea of life spreading the way I’m sort of
promoting it".

It's just risky to express, for cultural reasons, until there's tangible
proof. Many scientists are temperamentally reluctant to speculate without
conclusive evidence, especially given the penchant of the press to
sensationalize any such theories. It'd raise difficult questions about our
place in the universe, and possibly popular fears.

Thinking science had already settled on a consensus that simple life is
everywhere might even paradoxically reduce funding for new missions to test
the idea. After all, there have been tantalizing hints of life-processes on
Mars going back to the Viking lander experiments of the 1970s – and yet we
still can't seem to send a lab package that'd definitively answer the
question! But the hope of figuring it out motivates new missions.

(As should be clear, I'm strongly in Ruvkin's camp – and regularly comment to
that effect here on HN:
[https://hn.algolia.com/?query=gojomo%20panspermia&sort=byDat...](https://hn.algolia.com/?query=gojomo%20panspermia&sort=byDate&prefix=false&page=0&dateRange=all&type=comment)
)

------
Darthy
There was this interesting article posted here some time ago that plotted the
complexity of life found on earth vs time, and by using the right methodology
and logarithmic scales, it arrived at a nice linear line over many data points
and several billions of years. And the line converged to a 0 point, but that
point was a few billion years before earth was created 4.5 billion years ago,
adding more credibility to a panspermia theory. Can anybody remember that
article and its url?

~~~
Darthy
Update: found it. Apparently the theory is contentious, with accusations that
they cherry-picked their data points. Discussion:
[https://news.ycombinator.com/item?id=5580334](https://news.ycombinator.com/item?id=5580334)

------
kleer001
What if life is a fundamental property of a sufficiently complex universe and
a stable energy gradient?

That's where I'd put my money.

~~~
Koshkin
Hm. Also, money could be a fundamental property of a sufficiently complex
life.

~~~
kleer001
I understand the downvote, but I also agree with the statement.

IMHO money, markets, even democracy seem to me to follow directly from the
challenges of living in a complex society which follows from the benefits of
working at large scales.

They even seem to me to be simply abstracted versions of more naturally
evolved systems baked into life on Earth a billion years ago, i.e. ATP
metabolism and multi-cellular life

------
pfdietz
I have wondered if panspermia could have occurred in the Sun's birth cluster.
This cluster would have had a very high density of stars, with gas around them
to slow and capture material ejected from their neighbor systems. And the
asteroids in orbit around these stars would have still be warm enough to have
liquid water in them, so life could potentially have been seeded in a wide
variety of environments.

This possibility, if true, means SETI might be worthwhile even if the actual
origin of life is astronomically rare, much less than once per observable
volume of the universe. SETI would look at the other stars that were in that
cluster. Even if the rest of the universe were devoid of life, they (like the
continents of Earth, or planets in our solar system) could share the same
origin event.

This scenario might also explain why life apparently originated so early in
the history of our solar system: this sort of natal panspermia would
statistically amplify origin-of-life events that happened early on, by
multiplying the number of systems they'd affect. This amplification would
occur even if OoL was extremely rare.

------
DanielBMarkham
Based on nothing but faith and an irreducible cynicism, my money says we end
up going full circle, from "Earth is alone in the universe in regards to life"
to "Life is a fungus, found anywhere the most basic of conditions are met" (at
least over periods of millions of years at stellar scales)

People forget that this discussion is not necessarily related to life. When
various European explorers went out, in many cases they didn't know what to
expect. When they met strange peoples, most of them refused to believe these
were actually human.

It takes a good long while for humans to recognize other lifeforms like us. We
naturally think that we're unique, that wherever we call home is special and
the center of things. Combine that with galactic distances and it might be a
good while before we realize that the universe is actually full of aliens that
look just like humans only with bumpy heads (Obligatory Star Trek joke)

------
hirundo
Maybe we could test this someday with petri dishes in orbit. Outfit satellites
with catch basins that funnel into various potentially habitable pods and see
what grows. Park them in a lagrange point for better isolation.

But if panspermia is true such critters in the cosmic wind would be cousins of
life on earth, and it would be difficult (impossible?) to distinguish an alien
microbe from domestic contamination. If it's false we see nothing, and wonder
if it's because space is sterile or we're just not yet offering it the right
primeval soup.

~~~
bdamm
Panspermia doesn’t only work (if it works) by microbes floating in space.
Rather the idea is that microbes are embedded and somewhat protected in
asteroids which then land somewhere habitable. The occasional close brushes
between stars and their asteroid clouds provide the medium where microbes
could be transferred between stars quickly enough to launch and land before
the radiation destroys any hope of survival (like 20 thousand years.)

------
wycy
My biology knowledge is admittedly weak, but a question for those who might
know: a lot of the discussion here is about how we only know of "life" based
on nucleic acids (DNA). However, prions seem to replicate themselves without
the help of nucleic acids. Could this in some way be seen as a competing form
of "life"?

~~~
ecoled_ame
Prions don't synthesize themselves, they just self-assemble. RNA can encode
it's own information while also catalyzing self-replication.

------
DebtDeflation
It always seemed to me that the biggest argument against panspermia is the
relative hostility to "life" of space versus a planet like Earth. The
heliosphere protects the solar system from a significant amount of
interstellar cosmic rays and x-rays, Earth's magnetosphere offers additional
protection, and our atmosphere, particularly the ozone layer, offers
additional protection while also protecting against UV and high energy
particles from the Sun. Ionizing radiation and short wavelength EM radiation
are destructive to life and really the persistence of any large complex
molecules. Combine that with the vacuum of space and temperatures barely above
absolute zero and life originating via panspermia seems significantly less
likely than originating natively on Earth.

~~~
mywittyname
I'd say the biggest argument against panspermia is that the organisms
responsible for it need to be successful locally and universally, at the same
time. Reproduction is expensive and intrastellar reproduction is incredibly
low yield. So organisms would need to have evolved to both capture an entire
ecosystem AND waste a bunch of energy blowing their seed into the solar
system.

The idea just doesn't jibe with my understanding of evolution.

------
gremlinsinc
What if we began a 'seeding' experiment, suppose there could be more life but
isn't because life doesn't spread well in the vacuum of space. What if we
began sending bacteria and other micro-organisms to potentially habitable
planets via tiny spacecrafts. If we were to seed as many planets as we could
possibly find, then eventually (in a million years or so), this entire galaxy
could be teaming with life and the fermi paradox will be refuted as there will
be no way not to see the life that is out there. We may still not be able to
traverse the stars by that time at least not without generation ships but our
descendents could at least wave from afar and maybe communicate across vast
distances with intelligent life that we today helped seed/create.

~~~
titzer
I'm not really on board with the idea of just blindly infecting all habitable
planets with Earth life. We should look but don't touch until we have some
clue what the heck we are doing and why.

------
reggieband
What I find more interesting is the potential frequency with which new life
from origins other than earth has been mixed together with what is here. A lot
of stuff falls into our atmosphere and I doubt we know where all of it comes
from.

I commented today on a bit of dermatological discussion where they claim our
skin has a biome of bacteria. This is in addition to the gut biome that is
starting to look like it contributes to a wide array of human health issues.
Part of me wonders how much of those biomes (e.g. how many bacteria within
that biome) are from sources outside our planet.

~~~
rossdavidh
Well, if they did, then the fact that the basic DNA machinery is the same
implies that we and the alien bacteria had a common ancestor somewhere back
there.

~~~
reggieband
> implies that we and the alien bacteria had a common ancestor

My intuition suggests that wouldn't be necessary. For example, if I saw a
snowflake like structure on another planet I wouldn't be surprised since that
kind of structure is a result of the physical properties of the elements
involved. It could be the case DNA is very similar in that respect, a
mathematical necessity given the properties of hydro-carbons. I suspect the
science on that issue isn't settled.

~~~
anyfoo
Not a biologist, but my impression is that the concepts involved in DNA/RNA,
and especially the machinery around it, are so complicated and have so many
degrees of freedom, that snowflakes, which are rather simple crystallizations
of only water, may not be an apt comparison.

Maybe it's closer to, say, someone having just learned the basics of analogue
electronic circuits (but nothing beyond that), going into a basement, and
coming out with a fully formed IBM-compatible PC with USB ports.

Again, not my field, and I'm happy to be taught otherwise on that one.

~~~
insickness
If you're saying that DNA is too complex to have evolved on earth, where else
would it evolve? Panspermia just puts the origin of life in another location
in the universe. It doesn't answer any questions about how that complexity
would evolve.

~~~
throwaway2048
Thats not what is being said, hes saying that if life evolved twice, it would
be almost certainly completely different and "incompatable" at a molecular
level.

Consider the design of processor architectures and operating systems, similar
design goals but typically one cant run code from the other.

------
ShamelessC
I wish he had posited a theory for how life from Mars would have even gotten
here. Some comments have said an asteroid hit Mars and then redirected to
Earth with early life on it? Is that possible/likely?

~~~
AgentME
Yes, it happens. There are about 200 meteorites found on Earth that are known
to have come from Mars:
[https://en.wikipedia.org/wiki/Martian_meteorite](https://en.wikipedia.org/wiki/Martian_meteorite)

------
newsgremlin
Don't know if anyone has ever considered this (ignoring gross
simplifications), but as depictions of aliens are typically conceptualized
from creatures we see on earth. Is it possible that if we are the only living
creatures that have (yet) gained heightened consciousness, then spreading the
DNA of all life on earth across the universe in a similar fashion to how our
microbial life arrived on earth is how we ensure that life truly goes on if we
fail?

------
Grustaf
“...what if it started here and then spread elsewhere? And so we found some
sort of DNA on Mars, but that’s because it spread there from Earth. Is that
possible?

Yeah, but that sort of places us at the center of the universe, and all the
force of history is to say, “Don’t think of us as the center. We’re nothing.””

What kind of argument is that? Sounds like some kind of anti-geocentric dogma,
not an actual argument.

------
tempodox
And what if life did originate on Earth? That's one of those hypothetical
questions where the answer wouldn't make any practical difference, if we even
had an answer. If and when we find extraterrestrial life, maybe we can come up
with questions where the answers would be of practical value.

------
tychomaz
James Tour: The Mystery of the Origin of Life
[https://www.youtube.com/watch?v=zU7Lww-
sBPg](https://www.youtube.com/watch?v=zU7Lww-sBPg)

------
Causality1
>It just seems like, once it evolves, it spreads.

Hence why I draw exactly the opposite conclusion. It's my thinking that if
life existed throughout our 13 billion year old galaxy it would have evolved
to saoience and consumed all available resources long before the rise of
humanity. The fact our planet hasn't been strip mined or colonized is, absent
hard data, good reason to believe we're alone.

~~~
roca
There's a big difference between microbial life and intelligent life.

Bostrom and others have argued that, based on how long evolutionary milestones
took on Earth, the "difficult step" is actually complex multicellular life.

~~~
Causality1
The timeline implies that but experimentation indicates it may not have been
that hard.

[https://www.nature.com/articles/s41598-019-39558-8](https://www.nature.com/articles/s41598-019-39558-8)

[https://www.sciencemag.org/news/2018/06/momentous-
transition...](https://www.sciencemag.org/news/2018/06/momentous-transition-
multicellular-life-may-not-have-been-so-hard-after-all)

~~~
roca
That's interesting.

I agree with your conclusion that Fermi's paradox simply means there is no
other intelligent life, though I think the jury's still out as to where the
filter is.

~~~
Causality1
Indeed. There's quite a lot of debate surrounding it and a couple of
mathematicians arguing we haven't hit the filter yet, but I maintain hope
we're past it. It wounds my sci-fi loving heart to say this but humanity is
probably better off alone.

------
api
I've wondered for years if maybe the idea of life originating on Earth might
be the final geocentrism.

~~~
natechols
We haven't yet collected evidence that says terrestrial life originating on
Earth is impossible or even unlikely, nor has anyone produced an alternative
explanation that doesn't involve introducing additional external factors. It
may indeed turn out to be incorrect (although I wouldn't be on it), but it's
in no way comparable to geocentrism which simply couldn't be reconciled with
experimental observation.

~~~
perl4ever
If you lived on Long Island, and didn't know where humans came from, but you
knew about how big the earth was, would it be rational or in accordance with
Occam's razor to assume homo sapiens originated in your vicinity? Most people
would in fact be wrong if they even assumed humans originated on their
_continent_.

I feel like people get sidetracked into talking about evidence, when the issue
is that life originating on Earth should not be the _default_ assumption. I
feel like someone more lucid than me could make a good Bayesian sort of
argument.

~~~
Avshalom
It's not exactly the default assumption though. Historically the default is
that life was magicked into existence or came here from a previous world or
some other creation story. The current abiogenisis story of
molecules->proteins->cells->Life is relatively recent.

The other thing is that because we have a fairly... ?linear record of
evolution: if life did originate somewhere else it got to Earth in something
like prokaryotic single cell form 3.5 billion years ago. Which means we can't
use the idea of panspermia to tell us anything. It's neither predictive or
explanatory. It tells us nothing of how or where life _did_ originate or how
life got started on Earth or what or where we should look for or expect in the
rest of the Universe.

The current theory suggests life could pop up extremely quickly, which itself
already implies life is likely to exist in the rest of universe on some level
so panspermia doesn't even mean anything with regards to how likely life is
anywhere else.

------
AILove
What if this entire universe is an organism?

------
edoo
Given the complexity of DNA I think it is near obvious life did not originate
on earth. If you assume it did not originate on earth that gives you at least
another 10 billion years to work with.

~~~
gomijacogeo
No, it really doesn't; it took a few generations of stars exploding and
slamming into each other to make all those heavy elements we kinda consider
important. You _might_ be able to move it back another 3-4 billion years,
which is admittedly a good long time.

But really there's nothing yet that even remotely necessitates an extra-
terrestrial origin for life. The problem is that, each time there was a
"winner" in the very earliest more-chemistry-than-life arms-races, it
essentially obliterated all record of what the competition looked like. It's
not until pretty late in the game that no one new strategy obliterated all its
peers - at that point we got the biological domains (prokaryotes and
eukaryotes (which subsumed other prokaryotes as mitochondria and
chloroplasts)) and viruses. From then on, the arms-races have been at higher
levels of abstraction and the fight over the basics of biochemistry is
'settled'.

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dboreham
Wasn't there a movie about this?

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stewbrew
"It could be that I’ve never had a religious thought in my life."

The very idea that life has to originate from somewhere/somewhat and cannot
just happen sounds like a secular reformulation of a typically religious
statement.

