Attribution of foot bones to sex and population groups

Although cranial and pelvic bones are the preferred skeletal material used by forensic anthropologists to assign unknown individuals to their most probable sex and population (racial) groups, these remains may be unavailable. This paper presents models for classification using metatarsals, proximal pedal phalanges, and the first distal phalanx of the foot. Measurements include lengths and mediolateral and dorsoplantar widths of these foot bones. Four samples of 40 individuals each (black and white males and females) comprise the dataset. Models were developed separately for right and left sides. Three models are provided for each side: a metatarsal model, a proximal phalangeal model, and a combination model involving selected metatarsal and phalangeal measurements. A stepwise discriminant procedure was used for variable selection, with some highly correlated (r > 0.85) variables subsequently removed. The metatarsal models correctly assign approximately 77-84% of individuals to their correct sex and population groups; proximal phalangeal models yield correct assignments in 70-72% of cases, and the combination models give correct classifications in 87% of cases. Models exchanging variables selected from one side for corresponding variables on the other show discriminating power ranging from approximately 67-86%. More conservative "jackknife" estimates give correct assignments in 64-82% of cases. When these models are used for classification of sex alone, 86.2-93.7% ("jackknife" range, 84.3-91.2%) of cases are correctly classified; for race alone, 78.6-96.2% ("jackknife" range, 75.5-92.4%).