Shamans & herbalism

What if there is a more advanced system of cooking and mixing herbs, something akin to making dyes right now. For example, there are different herbs one could collect and mix/cook in some special and intricate way (the recipe has to be complicated and the materials hard to find), and these concoctions could increase life duration. This way, there can be advanced "shamans" who know various herb recipes and live longer than others, thus becoming the wisest person in a village, teaching regular people about things like farming and general village rules, and passing on their special herbalist knowledge to an apprentice, who would in turn become the next shaman and continue teaching the ways of the shaman to his apprentice. The increased life duration doesn't have to be infinite, could be 30 or 60 additional years (but I think the developer would know better how to balance this stuff), just enough to instruct a couple generations and tell everything they know to their student. I think that the addition of this would not only be very cool, but also could increase settlement stability and various social aspects, as well as add much more possibilities to RP.