Asymptomatic anatomical variations of the postcranial skeleton as a marker for human identification

Human identification is one of the primary objectives in a forensic context. In this respect, studies concerning the skeletal anatomical variations have revealed a great potential. These variants are used as secondary identification method within the scope of the assessment of ancestry and of the factors of personal identity in the reconstructive and comparative phases. However, not only are there few studies about the postcranial skeletal variants, but also there are a couple of current publications and most of the samples are not contemporary. The purpose of the present research is to obtain the frequency of asymptomatic osseous variants (AOV) of the postcranial skeleton in a current identified Portuguese sample. The present study addresses only the partial results for the upper limb, thorax, and lower limb. Altogether, 58 anatomical variants were analyzed. The sample includes 282 contemporary adult skeletons (148 females and 134 males) belonging to the 21st Century Identified Skeletal Collection housed in the Laboratory of Forensic Anthropology, University of Coimbra. The classification pattern of the variants is binary (0 for absent and 1 for present) and bilateral. The results show frequencies for the rarest ones with frequencies lower than 1% (duplication of acromial extremity of the clavicle, misplaced manubriosternal joint and dorsal defect of the patella) to the most frequent ones with frequencies greater than 50% (ulnar medial trochlear notch form, suprascapular notch and bipartite anterior facet of the calcaneus). The detection of an AOV in an unidentified skeleton, besides being an identity factor, could allow allocating that individual to a population where the same characteristic is very frequent. Therefore, the results provide contributions to human identification and can be used whenever a case of forensic anthropology is made.