Forget “eye of newt and toe of frog/wool of bat and tongue of dog.” People in the 16th century were more akin to DIY scientists than Macbeth’s three witches when it came to concocting home remedies for everything from hair loss and toothache, to kidney stones and fungal infections. Medical manuals targeted to the layperson were hugely popular at the time, according to Stefan Hanss, an early modern historian at the University of Manchester in the UK. “Reader-practitioners” would tinker with the various recipes, tweaking them as needed and making personalized notes in the margins. And they left telltale protein traces behind as they did so.

Hanss is part of an interdisciplinary team of archaeologists, chemists, historians, conservators, and materials scientists who have analyzed trace proteins from the fingerprints of Renaissance people rifling through the pages of medical manuals. The team reported their findings in a paper published in The American Historical Review. It’s the first time researchers have used proteomics to analyze Renaissance recipes, enhanced further by in-depth archival research to place the scientific results in the proper historical context.