Cooked Bones? Method and Practice for Identifying Bones Treated at Low Temperature

Abstract

Is it possible to determine low-temperature cooking in archaeological bones? The indirect exposure of bones to fire at low temperature (≤ 100 C), linked to cooking, produces macroscopic modifications on these bones. These modifications have not been clearly or systematically described previously. Instead, physicochemical changes at nanometric level are only now beginning to be understood. In this paper, our principle aim is to explore new methods and techniques that correlate macroscopic features such as smoothness or light transparency with physicochemical characterization results that could aid towards detecting cooked bones in the archaeological record.This study then selected 11 archaeological samples, both human and non-human. Bones were considered to be thermally treated or not, on the basis of macroscopic criteria. Complementary characterization techniques were used to study morphology (scanning electron microscopy and small angle X-ray scattering), structure (X-ray diffraction and transmission electron microscopy), local composition (energy-dispersive X-ray spectroscopy) and texture (gas adsorption). Indeed, fractal dimension, particle size, crystalline percentage or specific surface area may well explain some of the macroscopically observed modifications on these samples. The possibility that such apparent modifications may also be due to diagenesis is also considered.From an archaeological point of view, the results are promising. Our characterization of human and non-human bones demonstrates that physicochemical techniques are complementary and provide good criteria against which to distinguish boiled from un-boiled archaeological samples.

Aggressive or funerary cannibalism? Skull‐cup and human bone manipulation in Cueva de El Toro (Early Neolithic, southern Iberia)

“…The skull‐cup surface appears smooth and slightly vitreous when exposed to direct light. These macroscopic features have been observed when bones are boiled (Solari et al, ; Trujillo‐Mederos, Bosch, Pijoan, & Mansilla, ). Micrographs obtained by SEM showed a microscopic morphology constituted by ordered fibrils, with a smooth dense surface where the pore openings are obstructed, indicating diffusion and degradation of collagen fibrils (Figure ).…”

“…Images were treated with Helicon Focus v. 4.62 software. In addition, we evaluated bones with traces of indirect heat exposure at low temperature according to macroscopic (Botella, Alemán, et al, ; Pijoan, ) and microscopic criteria (Bosch, Alemán, Moreno‐Castilla, & Botella, ; Solari et al, ; Trujillo‐Mederos, Alemán, Botella, & Bosch, ). Surface morphology was studied at the micrometric level using a scanning electron microscopy (SEM) model JEOL JSM‐7600F coupled to an EDX Oxford INCAX‐Act.…”

Savoury Recipes and the Colour of the Tlatelcomila Human Bones

“…; Solari et al . ). On the other hand, the second group shows dark areas, and a morphology similar to that described in previous works for burnt bones (Holden et al .…”

“…; Solari et al . ). The Tlatelcomila bones, grilled and boiled, were found in the same location; therefore, the cooking of the meat was through a grilling or a boiling process.…”

Experimental Heating of Moravian Cherts and its Implication for Palaeolithic Chipped Stone Assemblages

“…; Solari et al . ) more or less modified by fire (see the overview in Mentzer ). The problem of the latter category—that is, the heating of stone materials—is dealt with in this paper.…”