New Guinea bone daggers were engineered to preserve social prestige

Abstract

Bone daggers were once widespread in New Guinea. Their purpose was both symbolic and utilitarian; they functioned as objects of artistic expression with the primary function of stabbing and killing people at close quarters. Most daggers were shaped from the tibiotarsus of cassowaries, but daggers shaped from the femora of respected men carried greater social prestige. The greater cross-sectional curvature of human bone daggers indicates superior strength, but the material properties of cassowary bone are unknown. It is, therefore, uncertain whether the macrostructure of human bone daggers exists to compensate for inferior material properties of human femora or to preserve the symbolic value of a prestigious object. To explore this question, we used computed tomography to examine the structural mechanics of 11 bone daggers, 10 of which are museum-accessioned objects of art. 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. Taken together, our findings suggest that human bone daggers were engineered to preserve symbolic capital, an outcome that agrees well with the predictions of signalling theory.

Rock Art and (Re)Production of Narratives: A Cassowary Bone Dagger Stencil Perspective from Auwim, East Sepik, Papua New Guinea

“…They used computed tomography to scan each specimen collected from the early–mid twentieth century, measured the properties of modern cassowary bones, and then compared their results. Their results suggest ‘that people in the Sepik region … engineered human bone daggers to withstand breakage, and that their prevailing motivation was to preserve intact the embodiment of symbolic strength and social prestige’ which concurs with ‘signalling theory’ (Dominy et al 2018, 10). In this context, the human dagger seems to be more powerful considering that ‘ emi bun bilong yumi [it is our bones]’, implying that these are their ancestors’ bones and, thereby, give them more strength in combat including tribal warfare (Newton 1989, 306).…”

“…However, he also mentions that they are common in inland East Sepik, but this is as yet under researched. Recently, Dominy et al (2018) analysed bone daggers (both human femur and cassowary tibia) from museum collections. They used computed tomography to scan each specimen collected from the early–mid twentieth century, measured the properties of modern cassowary bones, and then compared their results.…”

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Figure 3.Map showing the distribution of cassowary. (Adapted with permission from Dominy et al 2018, 4, fig. 5.

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“…Others have noted the importance of bone daggers made from cassowary bone and their use as personal ornaments (e.g. Dominy et al 2018; Newton 1989). In the case of cassowary bone daggers, they do not just ‘represent’ or ‘stand in place for’ but actively help to manifest and tell these narratives.…”

Anthroengineering: an independent interdisciplinary field

“…Fortunately for anthroengineering, several well-respected journals have been receptive to the publication of anthroengineering manuscripts (e.g. those published by the Royal Society [ 106 , 107 , 134 ], Proceedings of the National Academy of Sciences of the United States of America [ 12 ] and Nature [ 58 ]), but more explicit definition of the field will extend this acceptance.…”