Can someone dig without any books of knowledge using only shovels (therefore taking out only a few tokens)? If not, why?
You cannot dig unless you have at least 1 point of specialized knowledge in that region. From the rules, page 5:
If the player fulfills the requisites below, he can execute an excavation.
The minimum requirement
• The player has a valid excavation permission for the area.
• The player has at least 1 point of specialized knowledge for the excavation area, either from a researcher card or found item.