In the list thread, there's a debate about whether or not should the dwarves be able to know every kind of stone immediately. Some people think they should, because hey, they're dwarves, that the kind of thing they know from living underground.
The problem is, if you mod elves to be playable, they're still able to distinguish Bauxite from Granite and know that this peculiar stone is Satinspar. Also, dwarves know every kind of tree, which doesn't really make sense. I mean, I live near a forest and I couldn't tell more than 5 trees types. I don't know the difference between a spruce and a fir tree, and I wouldn't recognize a chestnut if I were to see one. Honestly, I really don't see why some guys that live underground most of the time should be able to instantly recognize every single kind of tree.
So there could be some kind of tags to add in the entities definition :
[ENTITY:HUMAN]
[STONE_KNOWLEDGE:medium]
[trEE_KNOWLEDGE:medium]
[ANIMALS_KNOWLEDGE:good]
[ENTITY:ELF]
[Entity:HUMAN]
[STONE_KNOWLEDGE:bad]
[trEE_KNOWLEDGE:perfect]
[ANIMALS_KNOWLEDGE:good]
For instance.
A "perfect" token would be the equivalent of what we have now : you know immediately what is this stone or tree, regardless of if you have already seen it or not.
A "good" one would be the same except for the exotic (= non-biome) trees/stone/animals (it will be displayed "an unknown stone" or "a strange animal" etc)
With a "medium", you could only distinguish the most simple stones/trees/whatever, the other will be displayed as "a pine-like tree" or "A deer-like animal".
With a "bad", you wouldn't be able to recognize the stuff by their name. It will be "a dark stone", or "a tall tree".
There could even be a "none" for really dumb races that'll only display "a stone" or "a tree".
After that, maybe you would be able to learn more while playing as an adventurer by examining trees/stone/animals (or talking with an expert in that field), and in fortress mode, there could be a noble (philosopher ? or another guy called "wise" or I don't know) that'll spend his time studying things (he might need samples, like a log of the tree, a rock, bones from the animals), and after some time he'll raise the knowledge of your fortress above the race's standards.