Underground Civilizations

While working with Deathawaken and Nigel on the underwater civilization essay, I got to thinking of another underrepresented environment - underground.

As such, I wanted to get some thoughts and opinions on how you think said civ would develop, what it would be like, ect.

To get started, some of the things I’ve noted:

  • Respiration: One of the biggest killers in cave systems tends to be a lack of airflow, so any civ that spends the majority of their time underground needs to ensure that housing receives some form of fresh air and remains unflooded.

  • Housing: Would they tend towards just series of tunnels, complex warrens, or closer to the palaces a lot of ants produce. I have the feeling, given the energy expenditure that building new tunnels requires, that everything would be clustered, but that’s just my opinion lol.

Anywho, anyone have thoughts? Opinions? Glaring issues with the entire concept?


Well…uh…I like the idea but uh…like in a speculative evolution book called “All tomorrows” tectonic plates moving could crush the species living underground, if they live in caves. Earthquakes would probobly be scary too.

I’d say this at least is partially cancelled out by the fact that the only threatening part of storms is the flooding, and that tornados are entirely not a threat. Also you missed something. Food. The only real source of food would be fish in underground rivers and root vegetables. That makes farming much harder, but it is still possible.

As for food, what about chemosynthesis or radiosynthesis, which both exist IRL, or thermosynthesis.
Then again, whether they’re capable of feeding an entire civilization, I’m not sure, since chemosynthesis requires constant digging or volcanic harvesting to use, and radiosynthesis requires a large vein of uranium, which is highly local; Thermosynthesis is most viable, only needing a heat gradient, but only exists hypothetically.

Another limiting factor is space, as rock is already almost as compact as it can be, meaning to only ways to get more room are to use a cave or the surface for more room. This would greatly limit the population of the civ.

Ant’s main killer, aside from people, are Paraisites (mites, Cordyceps, ect), other ants and the environment (flooding, unstable nesting medium, ect).

The planet Generator will have to make something below the soil but I see no reason why a massive eusocial species with a massive hive and tunnel network spanning the planet couldn’t be possible, you just have to watch out for revolts or building into the sea. Assuming the species has a social stomach and replates, food shouldn’t be a problem if said replates are connected just above the normal nesting system and are immobile when full. In the future they could be moved about by a magnetic system or something similar.

An earthquake may brake some tunnels but they could be redug in time and the replates will be drained for food by the trapped species, depending on the size of the species heavy rainfall may not be a problem but a flooding event will be.

Any thoughts?

Well I’d assume that an underground civilisation wouldn’t thermosynthesise/chemosynthesise/whatever themselves, but farm organisms that do.

Just like humans don’t eat sunlight but plants

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Yeah I’d take that as a given.