What if the pages of an old book could tell us who touched them, what medicines they made, and even how their bodies responded to treatment?
Renaissance medical recipe books are filled with handwritten notes from readers who tested cures for everything from baldness to toothache. For years, historians have studied these annotations to understand how people experimented with medicine in the past. Our recent research goes a step further. My colleagues and I have developed a way to read not only the words on these pages, but also the invisible biological traces left behind by the people who used them.
