So I am wondering if someone can clear up the history of japanese knives, esp with regard to single bevels vs double. Has japan pretty much always made both double and single bevels? Is the deba,yanagi,usuba, etc selection of single bevels what japan was primarily using 100 years ago? 1000? Just wondering about the history, long and short. Did pig-eating regions use double bevels 200 years ago? Were almost all knives steel harder than their counterparts in europe? How have knife profiles/styles changed?