A morphometric exploration of sexual dimorphism in mammalian skeletons for applicability in archaeology
The objective of this research is to identify and analyze sexual characters in mammalian skeletons in order to develop new methods for sex determination of archaeological animal remains. The study begins with an examination of the evolutionary and developmental framework of sexual characters, and a review of the current methods used for sex classification of animal remains. The materials and methods used in this research have been designed to locate the tertiary sexual characters in the fox, dog, pig, deer, and sheep skeletons. Morphometric and osteometric analyses of 11 elements of the post-cranial skeleton (atlas, axis, glenoid, proximal humerus, distal humerus, proximal metacarpus, innominate, proximal femur, distal tibia, astragalus, proximal metatarsus) have been conducted. Shape and size differences of bones have been analyzed using the F- test of variance and canonical variates analysis for shape variables, and discriminant analysis and the two-sample t- test for metrical data, to determine significance. Eigenshape analysis, an outline-based form of morphometrics, has been implemented for comparing bone shapes. Score plots have been produced by comparing eigenshape scores to indicate shape trends formed by the male and female bone groups. Mean shapes, calculated by the eigenshape program, have been superimposed so that differences in bone morphology between the sexes can be identified. Two alternative methods are introduced in this study, the Mean Shape Method for identifying sexual dimorphic or tnmorphic (with castrates) bones, and the Table Test for sexing canid humeri. These methods have been tested in a blind test to check confidence of sex classification. The new methods have been applied to bone samples from archaeological sites: Silchester for dog remains, Star Carr for red deer remains, and Canterbury for sheep remains. The results suggest that dogs buried at Silchester were female individuals, that predominantly male deer were hunted at Star Can, and that castration of sheep was practiced at Canterbury. Overall, the alternative methods developed here can aid in identifying the sex of archaeological bones more effectively.