Have you ever wondered if knives manufactured from frozen human feces could function as well as regular knives? While the thought has never crossed my mind, researchers at Kent State University and the Cleveland Museum of Natural History wondered about this very question, and sought to find the answer.

And yes, there's a good reason why.

In Shadows in the Sun: Travels to Landscapes of Spirit and Desire, Colombian-Canadian anthropologist Wade Davis recounted an ethnographic account (below) of an Inuit man who manufactured a knife, using his own frozen feces, to butcher a dog: 

“There is a well known account of an old Inuit man who refused to move into a settlement. Over the objections of his family, he made plans to stay on the ice. To stop him, they took away all of his tools. So in the midst of a winter gale, he stepped out of their igloo, defecated, and honed the feces into a frozen blade, which he sharpened with a spray of saliva. With the knife he killed a dog. Using its rib cage as a sled and its hide to harness another dog, he disappeared into the darkness.” - Wade Davis

Despite this story being shared across multiple documentaries, books, and academic literature, the credibility of this story remains uncertain. Can such a knife actually cut through hide, muscle and tendons? 

To test this claim, the researchers collected human feces to make such a knife. First, researcher Metin I. Eren went on a diet high in protein and fatty acids — consistent with an Arctic diet — for eight days. This diet included chicken thighs, beef fillets, turkey sausages, and salmon. From day four onward, Eren's fecal material was collected and frozen at -20°C. Frozen fecal samples were then either molded by hand or through ceramic molds to create knives. After burying each knife in -50°C dry ice for a few minutes, researchers attempted to slice through pig hide, muscle and tendons to test knife functionality.

Unsurprisingly, the knives manufactured from frozen human feces could not cut through the pig hide — let alone tendons or muscle. Instead, the edge of the knife would melt upon contact with the hide, and leave behind fecal streaks. Even knives shaped from feces from a typical Western diet failed to cut through pig hide.

To be clear, tools manufactured from human feces do exist. For example, you can be innovative when it comes to waste management in space missions, and use solid human waste to produce polyhydroxybutyrate and then 3D print items for astronauts. 

While there are countless tales reporting the innovative and resourceful nature of Indigenous and prehistoric people, this particular claim is unlikely to be true. The researchers do suggest exploring the role of different diets or even licking the frozen fecal knife (as reported in the original tale) to further test this claim, but regardless, they remain confident that they gave their knives the best possible chance to succeed and the knives still couldn’t function. 

So no, knives manufactured from frozen human feces do not work.

Just in case you were planning to try that out one day.