hello. this post has been removed as a "throughout history" question, which is against the subreddit rules:
If there's a particular culture/region (and perhaps timeperiod) of interest, do re-post. For example, is it the origins of Traditional Chinese Medicine, shamanistic practices somewhere in particular, medieval Europe, or how medicinal properties are identified now. Also, you might consider x-posting the question to /r/AskAnthropology and /r/AskScience as well, as both subs may have more to contribute from different perspectives.