And while many are little better than pseudoscience, some treatments like acupuncture are based on legitimate medicinal practices dating back millennia. So far, their work has almost doubled the number of known Dark Age medical manuscripts. Another 9th century manuscript’s suggestion for improving hair health starts sensibly enough— covering the head with herbal-infused salt and vinegar will help to disinfect the scalp of parasites. Meanwhile, a medieval doctor would be forgiven for thinking social media’s ability to amplify bad science amounts to demonology. In any case, hearsay, like in the Dark Ages, shouldn’t be taken at its word—be it in an ancient codex, or the latest hashtag.