[HN Gopher] Deep beneath earth's surface, clues to life's origins
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Deep beneath earth's surface, clues to life's origins
Author : rbanffy
Score : 63 points
Date : 2024-01-07 14:47 UTC (8 hours ago)
(HTM) web link (www.quantamagazine.org)
(TXT) w3m dump (www.quantamagazine.org)
| olddustytrail wrote:
| This is something I wondered about the idea of life beginning in
| the oceans and spreading to dry land.
|
| If approximately 70 percent of the total number of microbes on
| the planet live underground today (number I googled) wouldn't it
| make more sense that life began underground and slowly spread to
| the surface? Is this a theory anywhere?
| JoeAltmaier wrote:
| I favor the idea that a planet with a moon in a slightly
| eccentric orbit (earth) you have oceans washing minerals over
| every grain of sand on every beach, depositing then washing
| away different concentrations of everything, wetting and drying
| and applying sunlight and shade, warming and cooling. A billion
| billion petri dishes over a billion years. Eventually bingo!
| organic molecules then life.
| ninkendo wrote:
| I don't even think it's the eccentricity that does it, all it
| matters is that the earth isn't tidally locked with the moon,
| that's what gives you the tides: Earth is rotating faster
| than the moon orbits and so different parts of the earth face
| the moon within a day. It also helps that the moon is a
| significant fraction of the mass of the earth, which means
| its gravitational influence is significant to the oceans.
| adolph wrote:
| Eccentricities also contribute to long duration cycles of
| tides. Instead of all the Petri dishes following a single
| cycle, there is also another dimension of longer cycle
| dishes.
| orangepinyata wrote:
| It's an interesting suggestion but I think given what we know
| of life it's unlikely. I guess (obviously this is all
| speculation - none of us were there!) the origin of life can
| sort of be thought of as going from chemistry/geochemistry to
| biochemistry. And purely from a rate of reactions perspective,
| in a nice solvent like water that's likely to be more conducive
| to the origin of life than deep underground (in solids/highly
| viscous liquid at best).
|
| Then there's also flux - do you have temporal/spatial variation
| in your various chemical constituents that might give rise to
| potential gradients (as we find in life - chemiosmosis in
| mitochondria for an obvious example). These are very prevalent
| at the sort of Lost City hydrothermal vents, where you have a
| very nice solvent coming into contact with a large mineral
| flux, with large energetic and chemical gradients. Again, less
| likely to be found underground.
|
| If you're interested in this kind of thing I'd heartily
| recommend Nick Lane's book 'The Vital Question' or
| 'Transformer'. He tends to frame the issue not so much as just
| having the chemicals available (we find these on
| asteroids/meteorites!) but in having the energetic flux to get
| life started. Sort of akin I guess to how the components of a
| lightbulb don't do anything until you add an electron flux.
| freedomben wrote:
| I bought "The Vital Question" last year, but haven't read it
| yet. I started "Oxygen" by the same author though and found
| it a real slog. It felt like it occupied a hard position,
| assuming a fair amount of relevant scientific background in
| the reader, and wasn't really a book meant for general
| consumption. It's definitely possible I just wasn't in the
| right mental state for it.
|
| Did you find his books to be like that? Have you read Oxygen
| by chance and good compare/contrast them?
| orangepinyata wrote:
| I'll admit I haven't read them that recently but from what
| I recall the Vital Question is slightly more readable than
| Oxygen. That said, all of his books are very 'thorough' in
| the sense that he's definitely posing them as trying to
| make an argument as opposed to just educational, which does
| definitely make them less readable than they could be. Less
| bedtime reading and more something to actually make time
| for I guess?
|
| I have seen him give talks in person before and they've
| been a lot clearer - maybe there's some on youtube? He's
| been on a few of the 'In Our Time' podcast episodes, so
| they might be interesting too?
| syllablehq wrote:
| I posted another comment above about recent discoveries that
| the Earth has enormous quantities of hydrogen deep
| underground which is constantly bubbling to the surface - and
| in fact, flowing all the way up to the upper atmosphere and
| even escaping into space (!). So this would indeed seem to
| provide a flux even deep underground. Understanding this
| geologic hydrogen cycle is a fascinating new field.
| freedomben wrote:
| Yes this is definitely a theory already. The volcanic vents
| under the ocean particularly seem promising. I'm nowhere near
| qualified to even try to explain it without making certain
| errors, so I don't want to even try, rather I'll recommend
| someone who _is_ qualified (and good at teaching).
|
| If you're interested in this stuff, I can highly recommend
| Robert M. Hazen. He has an amazing Great Course called "The
| Origin and Evolution of Earth: From the Big Bang to the Future
| of Human Existence" that covers stuff in depth. There's a
| shorter one called "Origins of Life" as well but I haven't
| listened to that. My impression is that it's an abridged
| version of the former.
|
| Hazen also wrote a book called "The Story of Earth: The First
| 4.5 Billion Years, from Stardust to Living Planet" which covers
| the same material as the course (but in book form, obviously)
| and is really good. I liked the lecture-style of the course
| better personally, but they're both excellent resources if
| you're interested in this stuff.
|
| My only regret is that they're about 10 years old at this
| point. If anyone knows what has changed in the last decade in
| the field, I'd be fascinated to know.
| tectonic wrote:
| Came here to post the same thing, The Story of Earth is
| excellent!
| olddustytrail wrote:
| Oh thanks! I have an Audible subscription so just spent a
| credit on the Hazen great course.
|
| Mind you, I just started the Bach and the High Baroque so it
| might be a fair way into 2024 before I get to it. Maybe I can
| interleave them...
| freedomben wrote:
| Nice! I wouldn't worry too much. Once you start Hazen's
| course it will be impossible for you to stop :-D
|
| That Bach course does seem quite interesting though, I'll
| check it out!
| queuebert wrote:
| If you're interested in the origins and future of humanity,
| I'd recommend Isaac Arthur's YouTube channel as a
| complementary source as well.
|
| https://www.youtube.com/@isaacarthurSFIA
| olddustytrail wrote:
| Thanks, I'll check that out also!
| edgyquant wrote:
| Isaac Arthur is an engineer, so not exactly an expert on
| biology or anthropology. He does to a lot of futurology,
| but thats unrelated to the origins of life on earth and any
| speculation he does there is just that.
| comboy wrote:
| All life is made out of cells. All cells are filled with water.
| Phospholipids which make cells membrane arrange themselves into
| membrane because one part of them is hydrophobic and the other
| hydrophilic. Although I guess some water is present underground
| too.
| olddustytrail wrote:
| Well that relates to something I heard a few years ago about
| there being more water in the earth's crust and mantle than
| in the oceans. Isn't there some SciFi book along those lines
| with the water rising up? Not something I've actually read,
| but I'm pretty sure I heard about it.
| queuebert wrote:
| The water exists in the rock mostly like water exists in
| the silica packets in everything you buy these days --
| chemically bound in hydrated forms of crystals. That means
| it must be taken into account in any chemistry models, but
| not that there's a giant reservoir underground waiting to
| burst out in a flood.
| adrian_b wrote:
| The essential ingredient for the origin of life is a source of
| energy.
|
| The use of solar energy did not become possible until at least
| a few hundred million years after the appearance of life,
| perhaps only after more than a billion years, because the
| trans-membrane ionic pumps powered by solar light are extremely
| complex structures that could not have been created out of non-
| living substances.
|
| The only known energy source that can cause the appearance of
| life is the reaction between dihydrogen (elemental hydrogen)
| and carbon monoxide or carbon dioxide. Carbon dioxide exists in
| huge quantities everywhere on any planet without living beings
| (Earth is an anomaly, because most of the original carbon
| dioxide has been reduced and incorporated in living matter), so
| what is necessary for the appearance of life is a source of
| free dihydrogen. A gradient of ionic concentration in water is
| also helpful.
|
| Such conditions are present where either volcanic gases are
| released in water or in the so called alkaline vents, where
| rocks rich in iron are oxidized by water, releasing the
| hydrogen from water as dihydrogen (this is the
| "serpentinization" mentioned in the parent article).
|
| Both kinds of conditions are more typical for certain places on
| the bottom of the ocean, but they can be also encountered under
| ground, with the condition that there must be water infiltrated
| through the rocks, without water there is no source of free
| dihydrogen.
| lumb63 wrote:
| > The only known energy source that can cause the appearance
| of life is the reaction between dihydrogen (elemental
| hydrogen) and carbon monoxide or carbon dioxide.
|
| What do you mean by "the appearance of life"? These elements
| couldn't make even a single amino acid, so I'm not sure I
| follow how these molecules could lead to the appearance of
| life.
| syllablehq wrote:
| Very cool research. On the topic of hydrogen deep underground:
| I'm not an expert, just a fascinated amateur, but I've been
| fascinated by the recent discovery that there is enormous amounts
| of hydrogen below the earth. In fact, this article mentions
| hydrogen forming by serpentinization, and says that the
| researchers were shocked to find so much hydrogen. Recent
| research indicates that hydrogen may exist deep in the earth from
| processes other than serpentinization as well. There are now a
| handful of companies working to extract this natural hydrogen to
| use as a source of green energy. Exciting stuff.
|
| This is an excellent research overview on the topic of "natural"
| geologic hydrogen
| https://www.sciencedirect.com/science/article/abs/pii/S00128...
|
| I've also compiled some of my own notes on that paper here which
| provide some summaries on the multiple fascinating sub-topics.
| (E.G. hydrogen may be a driver of earthquakes! And we may be able
| to use hydrogen samples to predict earthquakes! Some predict that
| there may be even more biomass under the earth driven by sources
| like hydrogen and methane than there is above ground!)
| https://docs.google.com/document/d/1pnW4HRq6E2up0DhIoxjCyGS6...
| pixl97 wrote:
| If the Earth didn't have a huge internal geological reserve of
| hydrogen (and other gaseous chemicals) we'd effectively be a
| dead planet. It's easy to lose hydrogen to space, which is one
| reason we don't see much of it in the atmosphere. When we start
| talking about geologic timescales it would lead to the
| disassociation and lose of almost all atmospheric gasses.
| Luckily we have the tectonic plate cycle that puts new gasses
| in the atmosphere and kicks our eventual extinction down the
| road a bit farther. This also leads to earth shrinking over
| these very long time periods.
| jl6 wrote:
| Let's hope we don't find and extract so much subterranean
| hydrogen that we burn it into water and cause sea level rise.
| coder543 wrote:
| Don't forget that oxygen is useful for breathing too. Semi-
| important, I hear.
|
| ChatGPT estimates that if we converted all of earth's
| atmospheric oxygen into water (via burning with hydrogen),
| ocean levels would rise about 3.7 meters: https://chat.openai
| .com/share/c9c8ce51-6070-49b6-a092-86e4a4...
|
| I don't have time to check this math, so take it with a
| substantial grain of salt.
| random_ind_dude wrote:
| It will probably increase the concentration of water vapor in
| the atmosphere, which will lead to further warming as water
| vapor absorbs the heat radiated by Earth.
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