Cave adaptation

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Cave adaptation is a mechanic that causes dwarves who spend too much time underground to grow sick when finally exposed to sunlight. It is controlled by the [CAVE_ADAPT] token.

Exposure of cave-adapted dwarves to outdoor sunlight can cause one of two negative thoughts: "irritated by the sun" and "nauseated by the sun". The latter results from more severe cave adaptation and triggers profuse vomiting, which can leave an otherwise capable soldier momentarily defenseless. Cave adaptation causes no problems if the affected dwarves simply remain underground.

Prevention and treatment

First and foremost, be aware that cave adaptation requires much more effort to fully eradicate than it's worth. Most dwarves can spend their entire lives lurking in the dark with no negative consequences. Cave adaptation is only a major concern for your military dwarves, as they are the only ones who really need to be functioning at full capacity when outside. Menial labor dwarves sent out to build roads or structures can endure the unpleasant aspects of cave adaptation just fine, while dwarves you regularly send out to fish or gather plants will never become adapted enough to suffer more than mere irritation. Also, note that only dwarves suffer from cave adaptation. If this process sounds like too much effort, you might just want to recruit a few non-dwarven mercenaries for outdoor combat.

The only way to be cured of cave adaptation is to suffer its effects - once a dwarf has spent enough time to become adapted, stepping outside and being irritated or nauseated by the sun will instantly cure them. Any tile with the Outside trait will suffice (as long as it isn't raining).

Cave adaptation can be prevented by keeping your dwarves out of Dark tiles. Every moment spent in the dark slightly increases your dwarves' cave adaptation, but fortunately these tiles can be converted to harmless Light tiles with nothing more expensive than time, effort, and a large supply of rock blocks. Any tile that has had all its roofing removed becomes an Outside Light tile, the sort which is useful for treating cave adaptation. Building a roof over these tiles replaces the Outside trait with Inside, but leaves the Light trait untouched. These sunlit indoor tiles neither cure nor cause cave adaptation, making them perfect for housing those dwarves who will be heading to the surface often. Once you have a sizable workforce and some well-trained miners, it shouldn't take too long to channel away the top few floors of your fortress and reconstruct them with blocks. Doing this for your entire fortress, however, is almost certainly more work than it's worth. If you have a dedicated squad of soldiers for surface threats and convert their training and living areas to Light tiles, they should be safe from cave adaptation going forward, especially if you are regularly treating them to wildlife hunts and missions abroad.

Cave adaptation mechanics

• If a dwarf is in a Dark tile, cave adaptation increases by 1 every tick to a maximum of 800,000 (403,200 ticks is one year, so the maximum is just short of 2 years).
• If a dwarf is in an Outside tile while the sun is out (i.e. not raining or snowing) and their adaptation is at least 403,200 (1 year), there is a 1/1000 chance of the following happening every tick:
  • If cave adaptation is between 403,200 and 604,800 (between 1 and 1.5 years), the dwarf will become dizzy and experience minor pain and fatigue. They will also receive the unhappy thought "was irritated by the sun recently", and their cave adaptation will be reduced to zero.
  • If cave adaptation is at 604,800 or higher (1.5 years), the dwarf will experience nausea, dizziness, pain, and fatigue. They will start vomiting profusely and will also receive the unhappy thought "was nauseated by the sun recently", and their cave adaptation will be reduced to zero.
  • Otherwise, nothing happens.

Bugs

• Babies might be born cave adapted.^{Bug:8431[Verify]}

Explanation

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A scientific explanation of cave adaptation by Deus Machina.

Underground has low levels of light and very little air circulation.

Dwarves develop low-light vision (plump helmets are packed with beta carotene!) and their facial follicles become sensitive to the motions that a breeze produces against their beards, which allows them to tell where tunnels turn.

As they go deeper, their eyes become less relied upon, and they adapt further to rely on their whisker-based follication.

These eventually become so sensitive that, should a dwarf venture outside, the wind is the equivalent of multicolored and varying strobe lights. This is as aggravating to a dwarf's follication as a Pink Floyd show seen while sober is to our sight, up to the point of causing nausea.

While some have proposed beard shaving as a method of treating hyperfollication, these people are believed to be elf spies, and drafted to cavern exploring instead.