What is the origin of the phrase old wives tale?

Generally, "old wives tales" refer to sayings, practices or stories that have been passed down from generation to generation. Sometimes these practices are superstitious and seem silly. example: "If you keep making that face, it's going to stick that way." or, butter is good for a burn (which it is, not, by the way), knocking on wood after saying something bad (some people claim this keeps the nymphs inside the wood to stay there and not cause mischeif/bad luck)