DF is a land of mystery and wonder and death and {Gasp} Why is there no disease in the medical sense? No smallpox or plagues?
http://dwarffortresswiki.org/index.php/DF2012:Tower-capThere is much controversy about the energy source that tower-caps use to grow. Although it is clear that, like any fungus, they gain energy by breaking down organic compounds in soil and mud, it's equally clear that they are able to do this underground, without access to sunlight. Without any obvious way to regenerate the organic matter that they sprout in, it's unclear how they can survive for thousands of years without sunlight. Thus, useless immigrant dwarven botanists have wasted entirely too much spare time trying to find their energy source.
The leading theory is that underground soil may contain perpetual motion machines, composed of molecular-scale screw pumps and water wheels. As every dwarven engineer knows, a perpetual motion machine must be given water to start up, after which, it will run indefinitely without any extra water required. Molecular-scale screw pumps and water wheels would, similarly, not provide energy until they become muddied, and, similarly, would remain functional indefinitely. The concept of things smaller than monarch butterflies, however, has led to enormous controversy. Although, obviously, it would be hard to see something smaller than a butterfly, it should be possible to show that it exists because, just like butterflies, it would sometimes get stuck in doors and prevent them from closing. So far, there is no evidence that doors have been held stuck by imperceptibly tiny objects, so the theory remains unsubstantiated.
There is a substantial lack of disease transfer vectors in Dwarf Fortress, since microorganisms do not seem to exist.
Why can't dwarves take personal initiative outside of Moods?
Dwarves believe in perfection. There is a platonic ideal of every item, and masterworks are simply coming really close to said ideal.
Sometimes, a dwarf will decide he'll break the mold and make something different, possibly even using normally unacceptable materials for his craft. Those items are highly valued because of their uniqueness, and strangely effective. Aside from them, dwarves try to make their items all the same, decorations notwithstanding.
Also, personal initiative is what dwarves take when they get married. Or throw parties. Or eat. Or not pull the lever/go trade at the depot for whatever reason.
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Why don't dwarves eat land-dwelling small animals unless really desperate, while they do eat water-dwelling ones without much of a problem?