Human Bone Daggers

A human bone dagger (top) and a cassowary bone dagger (bottom). Image: Hood Museum of Art/Dartmouth College, Dominy NJ et al. Royal Society Open Science, 2018.

Forget your puny pocket knives - the people of Papua New Guinea know that if you want your friends and foes to take you seriously, you need a bone dagger.

Bone daggers are often carved with decorative patterns and used for hunting, fighting and for ceremonial purposes, as well as to signify social status - and even though most are made from the thigh bones of cassowary birds, the Sepik tribesmen of Papua New Guinea know that the best are made from human bones. And not just from any humans. "Human bone daggers have to be sourced from a really important person," said study author Nathaniel Dominy to LiveScience, "You can't just take the bone of any ordinary person. It has to be your father or someone who was respected in the community."

Now, science has discovered the technical reason why human bones make for better bone daggers. Dominy wrote in a paper published in Royal Society Open Science:

"We found that human and cassowary bones have similar material properties and that the geometry of human bone daggers results in higher moments of inertia and a greater resistance to bending.

"Data from finite-element models corroborated the superior mechanical performance of human bone daggers, revealing greater resistance to larger loads with fewer failed elements."

All in all, human bone daggers are twice as strong as cassowary daggers.