A comparison of cortical bone thickness in the femoral midshaft of humans and two non-human mammals.

Fragments of bone shafts that lack diagnostic features can be difficult to identify as human or non-human-an important task in forensic science and archaeology. Some workers have found the thickness of cortical bone in the shaft to be a useful distinction, although the sparse literature in the field is contradictory in how this may be applied. The aim of the present study was to determine whether any difference is discernible between humans, kangaroos and sheep (mammals whose remains are commonly confused with those of humans in Australia) at the femoral midshaft, with a view to a larger-scale analysis if differences were discovered. Cross-sections at the midpoint of the shaft were measured to determine the diameter of the whole shaft and the medullary cavity on each bone; an index describing cortical thickness relative to shaft diameter was calculated. Statistically significant differences were found between all three groups, with humans showing the thickest cortical bone, and sheep the thinnest. These differences may be linked to a higher load on the human femur, due to a larger body mass carried on two legs, as opposed to the sheep's four. Further work now needs to be carried out to determine if differences are present when comparing multiple sites on the skeleton, and between non-human mammals of different sizes.