Histomorphometrical and chemical analysis of human and non-human bones

Abstract

Aside from macroscopic features of bone and retrievable DNA, few methods are available to accurately separate human and non-human remains found in forensic contexts. The aim of this study was to determine whether significant chemical and histological differences between human and non-human bones exist, which could be used to sort them. Bone samples were taken from femora and tibiae of ten cows (Bos taurus), ten sheep (<i.Ovis aries), five impalas (Aepyceros melampus), 12 donkeys (Equus africanus asinus), eight cats (Felix catus), 12 dogs (Canis lupus familiaris), 12 pigs (Sus scrofa domestica), seven primates, 27 adult humans and six juveniles (Homo sapiens sapiens). Microelement analysis was conducted with a scanning electron microscope fitted with an electron dispersive spectrometer (SEM/EDS) and included the analyses of calcium (Ca), phosphorus (P), potassium (K), sodium (Na), chloride (Cl), sulphur (S), silicone (Si), aluminium (Al), magnesium (Mg), zinc (Zn), lead (Pb) and strontium (Sr). Statistically significant differences in the long bones of omnivores and herbivores were observed with regard to K (p=0.0001), Mg (p=0.0214), Cl (p=0.0001) and S (p=0.0012) levels, while K (p=0.0001), Na (p=0.0192) and Cl (p=0.0001) levels were significantly different between omnivores and carnivores. Subtle differences between femora and tibiae were also identified and warrant further inspection. Light microscopy was used to evaluate the histomorphology of cortical bone of the various species. Qualitatively the organisation of various bone structures were assessed while quantitative analyses included measurements of the total number of osteons and non-Haversian canals and minimum and maximum diameters of osteons and Haversian canals. All species contained Haversian bone either in their femora, tibiae or both bones, except for cow and pig bones which contained only plexiform bone. The presence of plexiform bone accurately excluded remains from a human origin. Statistically significant differences between species were found with regards to all quantitative variables, except for the tibial Haversian canal diameters. The current study illustrated that Haversian canal diameters of 60 μm or more and osteon diameters of 300 μm or more are indicative of primate remains and hence additional research is needed to separate bones of various primate species and adult and juvenile humans. Copyright