First of, we need to eat and rest and all that makes sense.
1:
But at some point we will have so much food that it will be more or less pointless to fish or forage, thats why we need food to "decay" or rot as well.
And that itself make sense doesnt it?
But there should be a way to "conserve" food? Maybe special "containers" or a special building? or salt cans for fish?
2: Region based resources it could be a special type of food, metal, rock or tree you or maybe even animals. With region specific X it will increase the willingness for trading.
Let's say for Armor A you need Z thats found in your region, but you also need X thats found on the other side of the map. This will make these items more valuble and a natural trade will occur
3:
Tracking? I mean its 2012 people should learn how to track, ever played one of those hunting games where you have to follow spilling and tracks on the ground?
Maybe with a high enough perception and the skill track you can use that to track animals or even human movements?
We can start with this for now, i have more things in my head but these make the most sense for now.