Radical Study Suggests Life on Earth Arose Twice

jjnord about 4 hours ago 49 commentsRead Article on sciencealert.com

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randomImmigrant•about 2 hours ago

The metabolic science is really cool. The conclusion that life arose twice requires you to buy that proto-cells that grew on these vents and needed those metallic surfaces to survive didn’t count as “life”. Then, free living cells, bacteria and archea, could maybe be argued as having independent paths as they plugged the gaps in their metabolism independently. Same DNA/RNA, same proteins. Same broad rules of metabolism. Just some alternate paths through chemical space to plug in the metabolic gaps and get free from metal surfaces.

To me, these are clearly not independent paths, but rather the branching of proto-life into two of the great kingdoms of life. It’s a stretch to call this two origins rather than a branching.

Then a couple billion years later, one of em ate the other, and rather than destroy it, they both started a symbiotic relationship, and we were off to the eukaryotic race. This is all the same web of life. Not two independent streams.

mycall•about 2 hours ago

You would think there would be some isolated places where proto-life still exists for this to be true.

Drakim•about 1 hour ago

Hash competition from life might cause them to go extinct, and even if it happens again it just gets out-competed to extinction fast.

binaryturtle•about 1 hour ago

I always found it odd that there's only one single origin of life point or even just a single common ancestor considered in history. Shouldn't entirely new life develop all the time on earth? I mean the ingredients and building blocks are still there, the environmental situation still should work out, like availability of water, temperatures, etc. We should see a constant emergence of new life all the time. Why would that process stop, just because some other life already exists? Maybe we just can't detect this, because whatever new life happens to appear —more or less— resembles life that's already there.

RetroTechie•31 minutes ago

> Maybe we just can't detect this

Probably this. How would we know what such 'proto-life' (perhaps even just some self-replicating soup of chemicals, no cell wall) would look like? Where to find it? How rare its occurence? Etc etc.

Scientists might not even recognise it if happened right in front of them.

I'd put my money on coming up with a more general definition of "life", and then looking for short(est) pathways from "soup of random chemicals" to "something in there that replicates (parts of) itself".

Doesn't need to look like life as we know it, as long as some elements of "self-organising structures, something being replicated" are there.

altcognito•about 1 hour ago

It has to survive though in the sense that it has to live long enough for us to see it. If we think of life as "spontaneously" (roughly speaking) emerging from the right conditions reasonably rarely, it has to outcompete other existing life for some time. And then there's the chance that we might not recognize it as "new" at all.

pfdietz•about 1 hour ago

> Shouldn't entirely new life develop all the time on earth?

It's possible OoL requires some exponentially unlikely step. We wouldn't realize that because of observer selection: had the step not occurred, we wouldn't be here to be thinking about it. There's a huge complexity gap between the stuff produced in OoL experiments and the simplest known life.

It's also possible OoL requires conditions that no longer exist on Earth, or that only existed in the early Earth (or wherever life got started in the Solar System). For example, if it depended on the existence of short lived radioactive isotopes or free ammonia.

numeri•about 1 hour ago

I'd imagine the bar for becoming new life is much higher now, because it requires finding a niche that isn't already filled by an existing organism or requires being immediately competitive with existing life.

jvanderbot•about 1 hour ago

Life is vastly faster than random chance at producing more life. So living things go fill niches faster than random chance can use those niches to produce new life.

Asraelite•about 1 hour ago

> Shouldn't entirely new life develop all the time on earth?

The fact that it doesn't is a pretty simple solution to the Fermi Paradox.

ck2•about 2 hours ago

the Great Oxidation Event caused all kinds of crazy stress = crazy mutations/adaptations where one eventually started our path

* https://en.wikipedia.org/wiki/Great_Oxidation_Event

one of my absolute favorite PBS Space Time on the subject

* https://www.youtube.com/watch?v=abvzkSJEhKk

gyomu•about 2 hours ago

The link the site points to seems like a better source (no ads, cites DOI etc, affiliated with AAAS rather than random aggregator website):

https://www.eurekalert.org/news-releases/1138775

gilleain•about 2 hours ago

Nice. This part was especially interesting:

> “When we react phosphite, a form of phosphorus that naturally occurs in hydrothermal vents, with organic compounds, we get metabolic phosphorylation reactions overnight in water. Phosphite and palladium replace ATP and enzymes; it’s amazing, and it makes early evolution a lot easier to grasp” says Schlikker.

As far as I know, there are no palladium enzymes ... checks ... ok, no _natural_ ones (that we know of). Which is interesting, as other enzymes in metabolism that use metals seem to have 'adopted' the metal(s) as a cofactor - like nickel, iron, molybdenum, even vanadium in at least one case.

andrewflnr•about 2 hours ago

The headline is a little confusing. They're still talking about a "split" between bacteria and archaea, so even under this theory, the very roots of metabolism and (I'm guessing) genetic code etc still have a single origin.

Anyway, it does provide a nice reason that bacterial and archaeal cell membranes are different.

MarkusQ•about 2 hours ago

Clickbait headline.

Should be "Life left mineral substrate at least twice" or some such. The research is interesting, but they're playing word games in the telling of it by saying the most recent common ancestor of all life wasn't alive (because it was dependent on a mineral surface), but two of it's children gave rise to lineages that were.

pingou•about 3 hours ago

If true, fl in the Drake equation just got much bigger.

lanstin•about 2 hours ago

They aren’t saying two totally different independent life creating event, they are saying that the earliest life depending on some external chemicals for parts of what is now covered by metabolism, and the tree of life diverged before those metabolic paths evolved inside the organism, so not totally the same emergence of life twice, but more stuff that reproduces and evolves but doesn’t meet modern standard for life.

ch4s3•about 2 hours ago

The science alert article should make this more clear, as its easy to get that impression.

pingou•about 2 hours ago

Yes I saw that, but the concept of "life" being quite blurry, I feel it still has an impact on the equation.

lanstin•about 2 hours ago

Honestly just more “biology has enormous areas without enough data that need filling in” causing previous generalizations (e.g. the central dogma of information flow being replaced by protein regulation of gene expression, non-coding DNA, even neurons and egg cells being produced thru life) to be overthrown, more than anything, IMO.

PaulDavisThe1st•about 1 hour ago

I have absolutely no doubt that the next LLM/ML startup will be able to confidently, rapidly, productively and correctly fill in the missing data. Onward science!

mellosouls•about 1 hour ago

Yep, now the probability of alien civilisations is completely unknown, but half the completely unknown it was before.

ChrisMarshallNY•about 2 hours ago

I was already under the impression that life on Earth has had several "Game Over -Play Again?" periods.

I assume that the difference here, is that it went completely to zero, before restarting. The other times, there was a bit clinging on, that seeded the restart.

victorbjorklund•about 2 hours ago

Sounds cool. Anyone with more knowledge that can say if this is really as proven as they suggest and if it is a big thing or not?

gyre007•about 1 hour ago

Major Seveneves vibes from this

peter_stokes•about 2 hours ago

unfortunately the field of abiogenesis, just like extraterrestrial life, is a lost cause.

The reality we will never be able to replicate creation of life nor find life on other planets (except via contamination). it's why we've never gotten any closer. and i'm not even religious

Qem•about 2 hours ago

Likely we don't need to replicate. We just need to get a sample of life with completely independent origin to our kind of life here on Earth, to study. This way we would be able to separate what are universal properties for any life from historical contingencies specific to us. To have samples of a single kind of life complicates things.

pfdietz•about 1 hour ago

Were that to happen it could be the worst news humanity ever receives, since it would greatly increase the chance the "Great Filter" is in front of us, not behind us.

ck2•about 2 hours ago

what's really going to blow your mind is our solar system looked completely different several times with different proto-planets and Earth/Moon is likely made from remnants of those other planets

* https://en.wikipedia.org/wiki/Formation_and_evolution_of_the...

pfdietz•about 1 hour ago

The Youtube channel Kyplanet recently had an episode on recent arguments that the Earth/Moon system was formed from at least three giant impact events, not just a single one between proto-Earth and Thea that formed the current Earth and the Moon.

qsera•about 2 hours ago

Origin of life on earth is not very interesting to me. Origin of life in the universe is where it is at...

usrnm•about 2 hours ago

Until we get any tangible proof of life outside Earth, there is no difference

qsera•about 2 hours ago

Actually I don't think there is life outside of Earth. I think we are truly alone in this universe.

pfdietz•about 1 hour ago

I agree. The Fermi Argument, and the apparent rarity of K3 civilizations in other galaxies, is to me powerful evidence of the scarcity of life. At the least, this suggests SETI should focus on distant galaxies where the Fermi argument doesn't bite as much.

ck2•about 2 hours ago

There is likely simple basic life as advanced as bacteria around the universe

But high level life was likely a series of complex accidents that is not reproducible or would be radically different than us

One of my absolute favorite PBS Space Time on the subject

* https://www.youtube.com/watch?v=abvzkSJEhKk

pfdietz•about 1 hour ago

> There is likely simple basic life as advanced as bacteria around the universe

What is the basis for this assertion?

theodorejb•about 2 hours ago

The idea that life came about by luck is completely absurd, even more so than thinking that a computer chip was created by chance erosion of a silicone wafer in exactly the right pattern.

As I see it life was clearly designed by God.

lanstin•about 2 hours ago

It’s a big universe and there are a lot of years, so chemical evolution seems like a decent tool for God to use. Much like General Relativity is a more efficient way to rule the world than assigning angels to push the planets thru the sky. And a passing familiarity with birth defects will prove to most hard hearted people that each specific fact of biology is not designed by a loving creator. Unless you believe this messy but gloriously complex universe to be the best of all possible worlds, right up till you lie to your friend, it is difficult to believe whole heartedly in a loving creator.

rationalist•about 2 hours ago

I'm not a biblical scholar, but I think the "loving creator" thing was invented by people and not necessarily in the Bible. I'm pretty sure Old Testament God is pretty vengeful.

Theistic Evolution is wide-enough belief, especially with Protestants.

andrewflnr•about 2 hours ago

It is definitely in the Bible. Cynically, God seems to swing wildly between mercy and vengeance, but it's clear he would feel justified in a lot more vengeance than he takes but doesn't because he loves people. Less cynically, he's planning for Jesus and salvation the whole time, and sorta trying to keep the evil from getting out of hand with the occasional smiting. You can make the logic work if you want to.

xkcd1963•about 1 hour ago

This is edging into religious debate, which the guidelines ask people to keep off HN

margalabargala•about 2 hours ago

Could you go into why you consider the existence of an invisible (all powerful? Depends which god you mean, you didn't say) being that happens to concern itself with life on Sol's third planet, to be less absurd than what you describe?

Or is that the joke and I'm missing it?

WelkinFolk•about 2 hours ago

I wish I were so vain as to think I'm so special, surely I could never have happened by chance.

victorbjorklund•about 2 hours ago

Do you reject evolution or do you believe God only created bacteria etc?

hollywood_court•about 2 hours ago

Which god?

adzm•about 1 hour ago

the Sun

TacticalCoder•about 2 hours ago

> As I see it life was clearly designed by God.

Which one? There are so many to choose from...

And what created that God? I know it's turtles all the way down but still want to know.

prewett•17 minutes ago

I believe that according to Catholic and Orthodox thought, God is Being itself. If you're familiar with Plato and Aristotle, God is the Form of Being. If not, I guess you could say God is Being as a noun, or God is where the idea of Being comes from. God exists because he is existence itself. (He is also Life and Love, in the same way)

wildzzz•about 2 hours ago

The dogma in many religions is that nothing created God or at least, there's no way to know. He exists outside our time and space. So from our perspective, God has always existed. If you believe that free will is true, then he can see all outcomes of the universe at once. If you don't believe in true free will, he sees the single timeline at once, from the big bang to the heat death of the universe.

Personally, I don't believe in any religions. They were all developed before we had a much clearer idea of how our world works and there's just too much folklore mixed in with actual, yet primitive, philosophical discussions to abide by any of it. But like with the simulation theory, we have no way to know what exists outside our time and space so you shouldn't worry. If there is some bored extra dimensional teenager simulating our universe on their GPU, it ultimately doesn't matter because we'll never know.