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Strange life-forms found deep in a mine point to vast 'underground Galapagos' (nbcnews.com)
162 points by hhs 45 days ago | hide | past | web | favorite | 57 comments

>Sherwood Lollar wants to sequence the genes of the Kidd Creek microbes and then do a 23andMe-style analysis to unravel their kinship to other residents of the deep Earth

Why woud a pop science author make free advertisement for 23andMe? genome sequencing and genome ancestry are older than some random company which does not even do full genome sequencing 23andMe only does genotyping...

Because more people today are probably more familiar with 23andMe so it's simple way of explaining it that people would understand.

the mission statement for a pop sci author should be to educate the public, this means not dumbing down.

the only avoidable reason it's more familiar to the public is because of all the previous pop sci authors preferring to say 23andMe instead of "genome sequencing" and "genome analysis" etc

if enough pop sci articles stop dumbing down the public would better understand what this is all about...

I don’t see how that’s some kind of horrific simplification...

It's an ad, and also kind of like calling making yourself french fries a "McDonald's-style process".

Genetics is both popular-culture topic and part of high school curriculum nowadays, so it doesn't need too hard explaining, and the kind of person that wouldn't understand the explanation probably also doesn't know what 23andMe is (which reinforces this being a sneaky ad).

(upvoted but)

also like calling making yourself fries making yourself "french" fries :P

Hah, sorry. I was taught that this was the correct universal way of calling this type of food across all varieties of English.

just to be clear, I think the rest of the article is fascinating and nothing else immediately disturbed me about it, it's just feedback in case the author checks HN

I think it's very likely that life has originated on Earth many times. If it happened once, so early in the age of Earth - it should happen more than once.

But the developed descendants of the first life outcompeted the later ones immediately so we only ever discover life that is related to us.

But if we search where life related to us couldn't go - maybe we'll find completely independent trees of life?

I personally doubt it. While abiogenesis is in progress but before it has produced life, the intermediate products are probably eaten by existing life. New forms of life are probably 'out-competed' before they even become forms of life. The conditions for the formation of life might be relatively trivial, but after it succeeds once it's unlikely to ever succeed again.

Of course, sterile experiments in a laboratory might give us a lower bound on just how trivial the requirements for abiogenesis are. So far nobody has noticed it happening in a lab, despite more than a few trying.

It is possible abiogenesis is such a low probability event that it occurred once since the exact conditions weren't met. The earth is not very similar to early earth currently.

Consider endosymbiotic hypothesis. The evidence is that it seems to have occurred at least multiple times (mitochondria, chloroplast, nucleus) in different geological eras. I would expect if life had a high enough probability to happen multiple times, it could occur in different geological eras.

> If it happened once, so early in the age of Earth - it should happen more than once.

You can’t extract a (meaningful) probability from a single sample no matter how intuitive it seems.

> You can’t extract a (meaningful) probability from a single sample no matter how intuitive it seems.

It's possible to get insights from a single sample. Science journals, especially in fields like medicine, do it to talk about atypical case studies. It's a good learning experience, too, when reflecting on the structure and context of those edge cases.

The terms “atypical” and “edge case” are not meaningful with a single sample size that is also the only known observation. There is only the one sample and that’s all you can observe. There’s nothing to compare it against to give “atypical” and “edge case” meaning. Individual samples can be meaningful in a larger distribution, but you still need multiple samples to establish any distribution at all. I think you are referring to outliers within the distribution.

People calculate probabilities with a sample size of zero, even.

For instance, people frequently talk about the probability a given voter will cast the deciding vote in an election.

But we use proxy effects like polls to simulate the actual event. On this case we haven't even been able to do that.

Ah, but is it a single sample, or multiple repeated samples at times t subscript n, with several negative observations and (at least) one positive?

Indeed, posit n repeated trials over a given time line, it seems equally implausible that an observation of a positive outcome earlier in the timeline contains no information on implied probabilities relative to a positive observation occurring later in the time lines.

> I think it's very likely that life has originated on Earth many times.

How would you prove that though?

Find life that doesn’t use DNA, or uses a radically different form of DNA.

How would you disprove it?

Asking for a way to falsify a theory is crucial. On this case I think we need to look for falsifiable predictions the theory makes that then can be disproven. If a theory makes no falsifiable predictions it's useless. So slightly backwards, it seems in this case, asking for how to proof it is closer to asking "what predictions does this theory make?".

A theory that's not disprovable isn't valuable. See Russel's tea pot.

Edit: phone auto typo.

Then why isn’t there ANY examples of life simpler than a bacterium, which itself is insanely complex? Why does all life share the same genetic and amino acid coding system, a relatively arbitrary choice?

More likely, in all seriousness, that life originated in Mars and came here via panspermia during the early bombardment period. Mars was warm and wet while Earth was still suffering cataclysmic impacts and only relatively mature examples of Martian life (e.g. bacteria) would have survived the trip.

If life originated multiple times on Earth there would be evidence for that. Heck if life originated on Earth there should be evidence for that, which there bizarrely isn’t.

ANY examples of life simpler than a bacterium

Viruses are much simpler, for one. Or perhaps you don't consider them to be life forms. Either way, if you understand how bacteria operate at even the most crude level, you'll realize that they (all bacteria, collectively; individually, they're specialized, of course) eat basically anything and everything in terms of organic molecules.

What are the ramifications for this? It means any sort of abiogenesis that takes place today needs to somehow avoid being immediately eaten by bacteria and then continue to survive for potentially millions of years in order to evolve into an advanced life form. Needless to say, this seems to be vanishingly unlikely these days.

As I vaguely understand it, both combination and separation have played important roles in evolution. Combination, for example, in that the nuclei, mitochondria and chloroplasts of modern eukaryotes derive from initially separate organisms.

Many eukaryotes carry transposable elements, which are DNA sequences that exploit DNA and RNA machinery to create numerous copies of themselves in the genome. That is, they're like viruses, except that for the most part they don't get transmitted, except through cell replication.

But I believe that there are examples where transposable elements do get transmitted like viruses. Or sometimes as parasites on actual viruses. So that's separation. And there are also examples, where viruses become integrated into the genome. Sometimes reversibly, as with HSV, which is why you can never really cure an HSV infection.

Anyway, it seems most likely that simple stuff evolved first, and then combined into more complicated stuff. But the simple stuff has survived, to some extent, as transposable elements and viruses.

Yes, although they are relatively simple compared to other organisms, viruses are still extremely complex when compared to the simple organic compounds you'd expect to form spontaneously in a pre-biotic world.

That is what makes all the difference. It's an enormous leap to go from a couple of amino acids to something able to survive and evolve and compete against other complex organisms.

Yes, agreed.

It is possible, I suppose, that remnants of other "starts" could have survived somewhere that's totally inhospitable to ours. Or perhaps, so different that they're not even food.

Discovering them would be very difficult, though. I mean, we have a hard enough time with all those "unculturable" bacteria. We only know them now through DNA technology.

I recently learned from "The Vital Question" that lateral gene transfer is not just a thing that occasionally happens, but something bacteria do all the time by default.

Anyway, I think we're still talking an order or two of magnitude difference between DNA/RNA (and supporting infrastructure) and the point at which proto life 2.0 transitions from "background chemistry" to "bacteria food".

I've so far read in detail about only one hypothesis on abiogenesis (in aforementioned book), and there the necessary environmental conditions were since changed by very existence of life.

I was trying to generalize from what we know about lateral gene transfer, and the history of mitochondria and chloroplasts, to the transition from proto life to life.

Something like "proto life A" and "proto life B" get incorporated into "proto life C" to make "proto life D". And after enough steps like that, you get life.

In a sense, that's a trivial statement. Because that's just what chemistry is about. Or deeper, just what physics is about. But regarding GP's point, I'm saying that it's too simplistic to argue about whether life originated once or multiple times. Maybe there were multiple beginnings, which combined and interacted in multiple ways. As we know now for evolution from primate-like ancestors to modern humans.

The machinery of DNA and RNA is one example. It's a chunk that worked. Or maybe multiple chunks that got combined. And the same with ATP synthase and the flagella motor.

Viruses are life, but they depend on the machinery of other, more complex life to reproduce. Life doesn't start with viruses, for if it did, how would they reproduce?

You asked about examples of life simpler than bacteria. You didn't stipulate that they had to be ancestors. How would that even work, anyway? An organism would have to be extremely long-lived to be living concurrently with its direct, more complicated descendent.

> How would that even work, anyway?

Think in terms of lines, not individuals. Mutations are acquired on individual level, so out of a whole family of bacteria, one individual may reproduce into something slightly different, while the rest of the family continue unchanged.

(Modulo fast mutation rate in bacteria, and modulo the wide use of horizontal gene transfer. The more I learn about bacteria and archaea, the more I feel there's little point in trying to find the tree of life.)

> More likely, in all seriousness, that life originated in Mars and came here via panspermia during the early bombardment period.

I am always surprised at the number of people willing to make assertions like this. Panspermia itself is a hypothesis. Panspermia from Mars specifically is a huge stretch. There is absolutely no basis for claiming that this is likely.

> only relatively mature examples of Martian life (e.g. bacteria) would have survived the trip.

Why do you make this assumption? Life complexity is not generally correlated with space survivability. At least not positively correlated.

I’ve actually worked in astrobiology research :)

I would point you towards the research that went into ALH-84001. Even if you don’t buy that it was an example of fossilized Martian life, analysis of the thermal stresses it suffered from ejection from Mars, time in flight, to impact on Earth showed conclusively that it was survivable. Had it been the other way around (Earth to Mars) it would have seeded Mars with life.

We’ve shown that rock which could be carrying microbes can and has been exchanged between earth and Mars. Lots of such specimens land each and every year. You can quibble that we haven’t found actual life yet, but

(1) lots of people think that’s exactly what ALH-84001 was.

(2) we don’t have that many samples of Martian meteorites. We know lots of it falls every year, but most is either not found/collected/identified or contaminated on impact.

(3) Mars meteorites falling now, ejected from a dry and sterile surface, would not be representative of what was falling in the early earth that was thrown from a wet, habitable Mars.

To be clear, from an astrobiology perspective a negative result from the search for life on (or from) Mars is harder to explain than finding it. Both panspermia and second abiogenesis are simpler explanations.

If bacteria have been riding meteorites to Mars for millions of years, why worry so much about sterilizing rovers?

I think finding life on Mars, even if you could prove it came from Earth through a natural process, would be significant. If you don't sterilize the rovers, then you can't trust the life is there naturally, and was perhaps introduced by us instead.

"Panspermia itself is a hypothesis. Panspermia from Mars specifically is a huge stretch."

I think "from Mars specifically" is something that requires evidence to treat as likely.

However, I don't think "Earth is the unique place where life originated" should be the default assumption according to Occam's razor. Nothing nearby is anything like Earth on the surface, but it's not speculation that there were billions of years and unimaginably large amounts of volume for life to develop underground in the rest of the universe, where it's warm and sheltered from radiation. The idea that nothing happened until Earth became "Earth-like" isn't the logical default. Naming the contrary of this far-fetched claim "panspermia" doesn't make it a "thing" that needs a "basis". By analogy, I would say that a creationist claim of humanity originating with Adam and Eve is what needs evidence, not the contrary assumption, that all humans had parents.

Where else? Venus' habitable period, if it existed, was quite short. It's gravity is also much higher and it is inward in the solar system. Even before it turned into the hell-hole it is now, dynamical models show that it probably sent few rocks our way.

The Moon appears to have formed without the resources to sustain life as we know it. There are great candidates for life in the outer solar system (Europa, Enceladus, Titan), but ejecta from these mostly get eaten up by the giant planets.

The only likely candidates for solar system origin panspermia is Mars, and maybe Ceres. Only Mars (and Earth) had the long wet period with open oceans, geothermal heat sources, plate tectonics, and sizable atmosphere. Mars isn't the only option, but the odds are way, way higher.

At least for life as we know it. But the point of panspermia is that it would be life as we know it ;)

It seems that we don't know how likely life is to develop given early Earth conditions. If that has a very low chance to happen then maybe panspermia is more likely. If it turns out to likely happen given a few million years and good conditions maybe panspermia is less likely. It seems to me we know almost nothing about the likelihood of either option, so it's hard to declare that one should be the default.

> "Panspermia itself is a hypothesis. Panspermia from Mars specifically is a huge stretch. There is absolutely no basis for claiming that this is likely."

Perhaps not 'likely', but there is reason to believe it's plausible. Extremophile organisms plausibly capable of surviving in space for the requisite timespans are certainly known to exist, and there is also known to be small amounts of material transfer between earth and mars.

The part I wonder about is whether any extremophile organism could survive the doubtlessly violent circumstances that are involved in ejecting rocks from either the earth or mars gravity well.

> Then why isn’t there ANY examples of life simpler than a bacterium, which itself is insanely complex?

Exactly because they were outcompeted?

If I understand correctly the early life would be living much slower and reproducing much less efficiently. So it would just get eaten by more efficient life that had millions years more to develop.

How do you know life isn't arising every few million years somewhere on Earth and immediately being eaten by something before it could reproduce 10 times? What evidence would you expect to find that it happens?

Fossils. Micro or nano scale tracks of chemotropic entities. Unusual small geological features indicative of anything other than normal random chemistry going on.

We can see all this in the rocks around us. TFA is about finding such things in mines deep underground. Remarkably we can even find such evidence in fossils more than 3 billion years old.

Yet.. the oldest things we find are microbial sedentary structures indicative of remarkably complex life: with genes, ribosomes, proteins, etc. We know this because those same life forms still exist today and leave pretty much exactly the same tell tale signs. We call them simple life, but that is just by comparison. They are insanely complex compared to the random geochemistry going on alongside them.

Why don’t we find ANYTHING older than this which differs from expected geological features? Where are the fossils from the origin of life? Also, the oldest fossils we have are of an organism that still exists: simple life remarkably doesn’t get competed to extinction. It turns out that simpler life forms have some advantages from their simplicity allowing them to be more adaptive to micro niches. So why don’t we have extant examples of even simpler life forms, surviving where complex life doesn’t fare as well?

Possible answer: there was a hard takeoff in complexity between the first thing you can call life with a straight face and some minimal level of complexity you need to stay alive and spread in the real world. That minimal level of complexity characterizes the first organisms that show up in fossils.

If it happened fast enough (maybe up to a couple million years, I dunno), there would be an infinitesimal amount of evidence that could easily be missed forever. If it only happened once, we would need to look at exactly the right rock, across the whole planet, with a microscope. Or it could already be recycled into the mantle. Ocean crust doesn't have a long lifespan, IIRC.

Dunno about the rest, but I do think that rapid advancement from proto-life to something pretty sophisticated is likely, wherever it starts.

Do we even know what we're looking for? Maybe some expected geologic features are the fossils of the first life?

How do we know if the tell-tale signs produced by modern simple life couldn't be also produced by proto-life? Maybe they used some of the same processes without all the other stuff modern life does?

Maybe life was bound to one location before it invented cells, and we just never checked that location? Maybe that location is now thousands meters below some ocean?

Mitochondria carry their own genome, which is substantially different to bacteria. Although nowadays a core part of eukaryotic cells, it's not hard to believe that they were once a separate form of life much simpler than a bacteria.

Considering the age of life on this planet, panspermia from Mars is unlikely; in the early life of the solar system, the sun was much dimmer and Mars was significantly colder than today. Any liquid water on the surface, on which life as we know it could have developed, would only be present in fairly recent history (no longer than a billion years really).

The theory I’ve seen is that anything simpler couldn’t defend itself and would instantly be eaten by something more complex.

Tommy Gold looks increasingly prescient. Refer to his book, “The Deep Hot Biosphere”, written nearly twenty years ago. (And check him out on Wikipedia - he also first stated how the ear hears different frequencies and that pulsars are spinning neutron stars.)

These organisms are close to the root of the tree. Photosynthesis came much later.

Tom Gold wrote that paper after the discovery of life forms in underwater thermal vents, during that period he was trying to build a theory of non-biological formation of fossils fuels the discovery of life forms living in extreme conditions at extreme depths made him reconsider his stance somewhat but not to abandon it.

His paper was about microbial life feeding on petroleum and so he postulated that it would have to reach several KM in depth at least.

I think there is an error/misconception in the first paragraph about this mine being the deepest spot on land ever explored (unless they mean by people physically walking around). To the best of my knowledge the Kola borehole in Russia is much deeper at 12,200 meters.


Speaking of strange life-forms, the first known fully anaerobic animal, discovered in 2014: https://en.wikipedia.org/wiki/Spinoloricus_cinziae

That is so cool.

I'd like to see a plot of "most cells in an organism" vs "average elevation/depth of habitat".

Very interesting. This gives us a good idea of what kind of life we might find on a planet without an oxygen rich atmosphere such as ours.

Life on Earth developed without oxygen.

The oxygen only appeared 2.4 billion years ago, as a side effect of photosynthesis and the event is sometimes called the "Oxygen Holocaust", since it caused almost all life on Earth to go extinct.


Yeah, that's the really cool thing. Most of the survivors likely live in the deep biosphere, well protected from oxygen. But some also survive on the surface, wherever there are anaerobic environments. Such as in some swamps and sediments, canned food, and far-gone wounds.

> "We’re finding that we don't really understand the limits to life,” Sherwood Lollar said...

As is often the case:

What we don't know > what we think we know

If there is life on Mars, that's where it is!

If you are daydreaming about how life started I can recommend ‘A New History of Life’ by Ward & Kirschvink for getting somewhat up to speed with the science.

tldr: we don’t know, and may never know

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