Does sexual dimorphism in facial soft tissue depths justify sex distinction in craniofacial identification?

Separation of male and female soft tissue depths into discrete groups for craniofacial identification implies that males and females differ enough from each other, with respect to this application, for this distinction to be useful. In this study, previously published soft tissue depth data were analyzed for sex separation. It was found that the variation within each sex was large while the variation between the sexes was small. Often the value of two standard deviations of the measurement for either sex was larger than the difference displayed between the means of each sex. Furthermore, opposite sex overlap in regions defined to be close to the male or female mean were found to be large and the amount of variance explained by sex was small (less than 6% on average). These results indicate that while male and female means at single craniofacial landmarks may differ slightly, and even at statistically significant levels, individual male and female soft tissue depths are often the same or very similar. On average, soft tissue depths of the face do display some sexual dimorphism but it is not marked and of little practical meaning for craniofacial identification where a single individual must be independently considered. Thus, there is little use in separate reporting of data for males and females and data should be combined to increase sample sizes.