Just in time for Halloween, devotees of death gathered at Philadelphia’s Mütter Museum earlier this month to talk all things postmortem for the fifth semiannual Death Salon. Among the gathering’s presentations were two forays into the not-quite-life sciences.
You can’t judge a book by its cover, says Daniel Kirby, an analytical chemist and independent conservation scientist, but you can determine if that cover is made of human skin. Kirby and his collaborators have been on a crusade to validate claims that some books in the collections of public libraries throughout the world are bound in human hide. Though you won’t find these fleshy tomes at your neighborhood Barnes & Noble, the practice—called anthropodermic bibliopegy—was surprisingly common in the late-18th and early-19th centuries, explained University of Southern California medical librarian Megan Rosenbloom. Then, some doctors performing autopsies saw fit to create such books from the deceased and inscribe details about the case within.
To verify claims of human epidermal bindings, Kirby and his colleagues use peptide mass fingerprinting. After sampling a nearly microscopic piece of the leather, the chemists process it with matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to determine the unique distribution of certain peptide masses in collagen. This distribution, or “fingerprint,” varies among species, thereby allowing them to determine one animal’s leather from another.
The team announced that of the 22 books they’ve tested, 12 are made with bona fide human skin. Collaborator Richard R. Hark, chair of the chemistry department at Juniata College, tested a famed example from his institution’s library and found that it was actually made with sheepskin, much to the librarians’ relief and some students’ chagrin. The historical medical library at the College of Physicians of Philadelphia, which houses the Mütter Museum, was found to have five examples of anthropodermic books—the largest confirmed collection in one location, says Mütter Museum curator Anna Dhody.
“We’re hoping this will raise the level of interest in finding out the authentic answer about the nature of these books,” says Hark, who adds that if any private collectors think they may have an anthropodermic book, they should most certainly reach out.
Throughout Europe, and especially in Italy, visitors to certain Catholic churches can view “incorruptible” saints—so called because their bodies are said to decompose at a miraculously slow rate. Elizabeth Harper, scholar in residence at Morbid Anatomy Museum, treated Death Salon attendees to a slide show of some of these enduring corpses. Over the past few decades, she said, scientific explanations for unintended mummification have led the Catholic Church to downgrade incorruptibility from a miracle to merely a good sign.
What scientific explanations could possibly cause a body to avoid putrefaction? One cause is saponification. In these cases, a humid tomb allows bacteria from the corpse’s microbiome or the surrounding environment to convert the body’s liquid unsaturated fat into solid saturated fat. The result is adipocere: a soaplike substance that allows the mummy’s soft tissues to hold their shape instead of rotting away. The Mütter Museum, where the Death Salon was held, has an example of this (without ties to sainthood) in a mummified whole-body specimen dubbed the Soap Lady.
Harper also revealed that some bodies alleged to be cases of incorruptibility were later exposed as very intentionally preserved. In these cases, typical embalming fluids, such as formaldehyde and methanol, were responsible for slowing decomposition.