Another one that I enjoy toying with is the idea of massive water filled subterranean pockets within the Earth. Basically places with their own weird ecosystems that have developed in near isolation for nearly hundreds of millions of years.
There is actually something like this that has been confirmed, although not to as great of a biosphere as you might like. There was the whole
Ophel biome(sorry there's only a Deutsch version of the wiki article) that was proposed in response to the amphipods in the
Ayalon cave. To summarize it: it's a proposed biosphere that lives in aquifers and coastal cave(
anchialine) systems around the world and derives its energy largely from geochemical processes. The amphipods from the cave
were found to not reproduce within the cave and were believed to be reproducing in the surrounding aquifers and coming to the caves instead to feed.
The group those amphipods belong to,
Thermosbaenacea, are a large group of troglobitic(cave bound) amphipods who have a distribution around the world that fits very well with the break up of Pangea(due to their cave-restricted lifestyles and their lack of any non-cave dwelling relatives, this suggests that their common ancestor was troglobitic too). They're a good deal of the support involving the Ophel biome, which to be fair is pretty much all but confirmed just not in a very large sense. Many anchialine caves do in fact have all kinds of life within them and then there are spring-fed cave ecosystems like
Movile cave that are found living in isolation for millions of years. I did a whole big post about that cave in particular in the fun facts thread if anyone wants to read more on that.
Interestingly, the Moon that /x/ says has a space station orbiting it, has the same qualities of Earth, Iron core, internal oceans.
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The internal oceans for the Earth aren't actual oceans. Journos read the geologists' term for water, which in deep rock contexts refers to minerals with lots of hydrogen(oxygen is a given since it's the most abundant element on the planet), as liquid water. In reality what they found was evidence for large deposits of
ringwoodite with hydroxides trapped within suggesting tons of hydrogen in mineralogical form in the mantle. This is actually to be expected, the cycle of plate tectonics with the oceans actually traps tons of water as oceanic crust is recycled into the mantle and volcanoes release tons of water vapor all of the time. They just never had any way before to even try to get an accurate guess as to how much "water" was trapped down there. Don't take their current estimation as gospel though, it is still very speculative.
The oceans on Ganymede, to my knowledge, are different though and may actually be liquid water based due to the icy crust covering it all. This isn't much unlike Europa. I believe there's also radio-based data helping to confirm that too, but I haven't looked into it.
4. Humanity started building civilizations or attempts at civilizations far, far earlier then what’s in the “official” books. You’re telling me for 250,000+ years we just sat on our asses in caves scratching our butts? How advanced they could have gotten is anyone’s guess but I wouldn’t leave agriculture and bronze working out of the question. One of these could have been wiped out at the end of the ice age, their former cities and towns degraded by natural elements and now below sea level.
You, and anyone else interested in this notion, would very likely be interested in the
Calusa people of South Florida. They actually formed a fairly stable and prosperous kingdom without agriculture, all whilst being surrounded by native Americans who did have some forms of agriculture(as by the time of Columbus many tribes had some agriculture, they weren't all hunter-gatherers). They even lasted for centuries before Columbus's discovery of the Americas and for a good time after coming into contact with the Spanish. Instead of relying on crops for food they relied on traps, waterways and so on to gather large amounts of aquatic animals to eat and they had various ways to prepare and store them. They would even dig big storage pits to keep tons of tiny fish alive to be later harvested.
This is to say that civilization is not dependent on agriculture, as is often proclaimed. At least one people group in not-too-distant history was able to have civilization without it and seemingly others from some archaeological finds(
Gobekli Tepe may be one such site as there isn't a lot of evidence of agriculture and the site was either formed near the very earliest agriculture in the region or before it and I remember there was another site somewhere in Russia that suggested civilization but was dated to being loooong before agriculture ever came to the region). All of that being said though, it's my belief that these kinds of civilizations are not as "virile"(for lack of a better term) as agricultural ones. The problem is that the Calusa had a very complex system in order to manage their foodstuffs and when major conflict came from the Spanish they were so utterly wiped out that much of their ways were totally lost and historians still aren't sure how their people group disseminated after the collapse.
Agriculture on the other hand is very simple. The problem is that with agriculture, as we have it, is that it requires a great deal of selective breeding on your foodstuffs before it's viable to sustain a major population. Selective breeding like this can occur without intention, as a kind of feedback loop, but it's not the most likely thing to occur without civilization. Once you have those species though they tend to spread. Potatoes spread all the way across the Americas, well into Mexico, from their origin in the Andes mountains with the Incas. Likewise to corn, wheat and so on. Those crops spread and jumped cultures and people groups very easily. If your civilization collapses, you can bet that nearby peoples are still farming the crop that made yours possible and will therefore be able to follow in your footsteps and take advantage of the sudden power vacuum. Building a more complex animal husbandry based civilization is much more work however, but it is almost certainly the end point for hunter-gatherer peoples who advance enough in their mastery of their ecosystem(s).
10. Mars once supported a biosphere much longer then expected with complex multicellular life before a colossal extinction event wiped it all out.
There's good reason to believe that Mars still has life on it. There's
seasonal methane production on the planet to this day and the initial tests to try and detect life from that one rover may have actually killed the organisms it was trying to detect. Water is scarce on the Martian surface and so pumping in too much is likely to be extremely harmful to the kinds of microbes that would've adapted to those extremely xeric conditions.
A good candidate for future missions to try and feed that life would probably be minute amounts of
tholins. From what I remember too, from the recent asteroid sample return one of the samples got contaminated with Earth bacteria. It provided an extremely useful insight though as the bacteria that had contaminated the sample ended up flourishing on the various organic carbon sources and other molecules in the asteroid, much of which would include things like some amino acids and tholins. With methane being produced on Mars, and there being no thick atmosphere to shield it from UV radiation, tholins are a definite presence to expect on Mars. If they're naturally present on Mars then you'd expect any life still there to have adapted to make use of it.
Here's an
article talking about that asteroid sample contamination too.
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