Preservation of Human Bone Remains at Joya De Cerèn

Bone, a key part of the paleontological and archeological records, can provide insight into the biology, ecology and the environment of ancient vertebrates. Bone is a composite material in which the nanomechanical properties are dependent on the local organic content, mineral content, and microstructural organization. However it is unclear as to how these properties are affected by burial, environmental influences, temperature, or time. The acidity of volcanic soils causes resorption of the bone mineral and may result in demineralization of the bone. As such, very few bone remains are found in volcanic soils and this rare sample can provide insight into the preservation under such extreme conditions. While the effects of volcanic soils on bone are unknown, exposure to hostile environmental conditions increases the potential for dramatic alteration of the mechanical behavior. In this study, a human long bone from around 600 A.D. and a modern human femur were studied using nanoindentation. Testing, performed in both longitudinal and transverse directions, revealed preservation of bone’s natural anisotropy. Additionally, the preserved bone’s lower modulus values suggest the dissolution of bone mineral.