By “macro-life” I just mean large, complex life such as are we humans or is the oak in my backyard.
A recent interest in landing on other planets has led researchers in many different fields to try to physically simulate extra-Earth conditions in Earthly spots; such as, Antarctica, icy mountain tundras and boiling springs.
Most of the search for extra-Terrestrial life is centered on microbe-sized life, such as bacteria. This process has led to the following extract from a JPL/California Institute of Technology report:
Almost everyone believes that our great, great, great…great grand-ancestors were bacteria. If the surface bacterial life evolved into multi-celled, complex forms such as we humans and other plants and animals, is it possible that the deep subsurface bacteria also might have evolved into large, complex forms?
Rephrased: Is it possible that a few miles beneath the surface, Earth has an structure of large, complex lifeforms, living and evolving in the darkness of their cavern homes?
And if this evolutionary process is possible, what might be the implications of co-equal or even superior civilizations existing, growing, and evolving under our very feet?
Parameter, I’ve read your OP twice now, and I come away with the impression that you want to know if we think there might be oak trees growing on Jupiter, or miles below the surface of the Earth.
One vote here for “no” on both counts…
eh, you start out talking about “macro-life” like oak trees, and then you abruptly switch to “micro-life” like bacteria. Make up your mind, 'kay?
A) Have no proof. Or, come to think of it, any evidence whatsoever.
B) They probably aren’t Tremor-style size lifeforms, and they almost certainly do not have any intelligence. If for no other reason than the lack of space - I don’t think there are any caverns there that far down.
I think he made sense. The point was that since we know that bacteria can live deep underground, might they not have evolved into more complex animals just like they have done on the surface?
you didn’t mention a reason. I don’t think that smiling bandit is correct about the geology a few miles below the surface: We store strategic materials is vast salt caverns; both Carlsbad Caverns and Mammoth Caves go down quite some distance; petrolium is pumped from natural caverns quite a distance below the surface. I think that there would be plenty of room for microbes to evolve into larger, more-complex things.
Since you followed my thesis, smiling bandit, did you have a specific reason for your “no way” response?
No, no, Ms. Goose. Astrobiology–which was called exobiology until recently–drove the research direction which, in turn, led to the recent discovery of huge quantities of sub-surface bacteria. Certainly macro-life under Jupiter’s Europa or Io would be an interesting speculation, but I’ll leave that for NASA: My thoughts are about a few miles below us.
Yeah sorry about that. I meant to imply that I agreed with smiling bandit’s comment on lack of space. I agree that there may be large caverns down there (though I can’t produce evidence either way) but I just don’t see how there could be spaces big enough to support a fully functioning ecosystem. Sure there could be a few new species of primitive fish or fungi but I can’t imagine any truly complex animal emerging.
If, if, if they are down there, then probably the same way we did it up here on the surface.
You are moving the evolutionary change process much too fast, Funky McDuck. Some of the earlier surface-bacteria made huge coral-like colonies and, for all intents and purposes, actually acted to change the environment which, in turn, perhaps, made a different, more acceptable environment for later single-celled things–the next big step in the evolution from bacteria to mammals.
Even very small caves would have plenty of room for single-celled algae, for example. Of course they wouldn’t exactly be algae as we know them since their entire physiology would be massively different. The bacteria that were just reported living deep beneath the surface, use hydrogen for fuel. So too, I suppose, would the next follow-on: some sort of alga-like cellular species. They, in turn, might have been followed by some multi-celled species–as we know happened up here on the surface.
As with the plants using light for energy and exuding oxygen–thus allowing we oxygen-breathers to arise–some similar environmental transformation might have taken place far below the surface. Etc.
I remember reading about an underground cavern that was discovered that had been completely sealed off from the outside (although probably not sealed off to gas and liquid entering and escaping through porous rock); there was an entire ecosystem in the cavern based on the organisms that presumably had been present in the void at the time the forces of nature sealed it up; there were bacterial mats that were existing largely on chemicals leached out of the rocks, but there was a lrge diversity of small invertebrates that were either grazing the bacterial mat or eating each other.
Not overly germain to the OP, but there is some credible suposition that the prevalant theory of petrol-geology might be incompleat. In The Deep Hot Biosphere Thomas Gold sugests that not only is there a sub surface biosphere filled with anarobic bacteria, but that bacteria may infact be produceing oil. Definatly a minority opinion in need of further research, but intresting to say the least.
Sorry to rain on your parade, but petroleum is NOT pumped out of subsurface caverns. Nor is there some kind of hole left after the oil is removed. Oil is found in porous rock, somewhat similar to a sponge. Limestone caves go down a few hundred to a thousand or so feet at max. Farther down than that there just isn’t any room for macroscopic life forms.
The bacteria are interesting though.
Thanks, Testy, for your comment: “Sorry to rain on your parade, but petroleum is NOT pumped out of subsurface caverns. Nor is there some kind of hole left after the oil is removed. Oil is found in porous rock, somewhat similar to a sponge.”
A similar thought crossed my mind a couple of hours after I posted the words “…petroleum is pumped from natural caverns…” What’s especially embarassing is that I worked for several months in the Petroleum Resource Recovery Center, for a real, live Ph.D. in Petroleum Engineering, and should have known better.
After about 2 hours of Googling the seemingly vacuous information-wastelands of Earth Sciences, Testy, the best I could come up with was this comment from a page at Byte.com:
From this 5-page article and from this and that at http://EarthRef.org, it still seems to me that for about 40 miles beneath the surface large fissures and caverns would be possible to form and maintain long-term stability. Whether that stability could last the billions of years needed for large-scale lifeform evolution, I don’t know.
The fact that deep earthquakes extend well into the mantle, well below the crust, seems to say the fissures could form. The temperature to about 40 miles or so below the surface being low enough to leave rock brittle and solid, would seem to say that such holes might stay intact for a very long time.
Where did you get your information that below a thousand feet, there “just isn’t any room for macroscopic life forms”?
Frankly, I don’t have an authoritative source for that comment about there being no room and certainly claim no expertise at geology. On the other hand, I’ve seen seismic charts that show the various strata very clearly and would expect a discontinuity of some kind to be even more apparent. The charts I have seen were for oil exploration and very localized, covering at most a few miles in area and only a few thousand feet in depth. Possibly some organization studying earthquakes and similar phenomena would have charts showing larger areas and deeper slices of the earth.
As a side issue, think of large caverns occasionally appearing throughout the crust and then collapsing after a given period of time. Without some connection between them, the life forms would have to independantly evolve in each cavern.
Fascinating subject though, even just the bacteria.
Think or Crete, Testy, or any other small place that evolved a noteworthy human civilization. One would probably be enough, if the cavern didn’t collapse–resources would be everywhere. Thanks though.
I was under the understanding that most caverns are relatively young in geographic terms…they don’t last long enough for macroscopic life to evolve from single-celled organisms. The life found in caves is always surface life that adapted over the thousands of years to the subterranean conditions.
As to hypothetical vast caverns that have never been accessible to the surface, what kind of biochemistry to you expect the life to have down there? It’s not going to have much, if any, oxygen, as that gas is only common on the surface where there are photosynthetic lifeforms to produce it. There IS anaerobic life, but in billions of years it’s never made the jump to multicellular, probably because anaerobic metabolisms are very low-energy.
Finally, anything living far underground will need a way to move from cavern to cavern, as the Earth’s crust is constantly moving and none of these caverns would be permanent.
I think it’s unlikely for their to be macroorganisms far beneath the surface. There’s just no reason for them to evolve, that’s the kind of environment that is dominated by single-celled lifeforms that can live down there without needing caverns or advanced burrowing organs.
The biochemistry of the sub-surface bacteria just found seem to get their energy from hydrogen, leaching(?) out of the rocks or the product of mineral breakdowns. I don’t know about the energy capacity of a hydrogen biochemistry or if there even is such a capacity at a multi-celled level, but the automotive engineers seem to think that there is a fair amount of power to be derived from pure hydrogen.
As I see it, the real problems are the size and longevity of the sub-surface caverns. I don’t know enough about either a hydrogen-based biochemistry or sub-surface geophysical structures to make any intelligent estimates.
Considering that we are pumping aquifers dry, worldwide, it would seem that if there is any possibility of sub-surface macrolife, we need to take it seriously–at least as seriously as we are taking potential life in Lake Vostok in Antarctica or on bodies such as Europa. In both of those places, scientists are taking extraordinary care to not pollute nor disturb any hypothetical lifeforms.
