Short communication Determination of sex from the metacarpals in a Thai population Pongsak Khanpetch a , Sukon Prasitwattanseree b , D. Troy Case c , Pasuk Mahakkanukrauh a, * a Department of Anatomy, Faculty of Medicine, Chiang Mai University, Thailand b Department of Statistics, Faculty of Science, Chiang Mai University, Thailand c Department of Sociology & Anthropology, North Carolina State University, USA 1. Introduction Identification of unknown individuals from their skeletal remains is much more difficult than from study of a cadaver. Yet there are occasions when the remains of a deceased person are found after significant decay, often leaving only an incomplete skeleton to help provide information about sex, age, race, stature, and cause of death. Determination of sex using human skeletal remains is one of the more important subjects in the field of forensic identification, because it is a precursor to the study of other individual attributes such as age and stature. However, to be most effective in a forensic context, sex determination methods that apply to whatever portions of a skeleton are best preserved must be available. Once effective methods have been created and verified, sex determination using measurements of bones is less expensive and time consuming than other techniques such as DNA or chromosome analysis, and implementation is simple enough that public health personnel without a background in skeletal analysis can be trained to measure human remains for this purpose. Sex determination from skeletal remains is so fundamental to forensic identification that sexing methods based on measure- ments have been developed from many different areas of the skeleton, including some bones that are less commonly the subject of research such as the clavicles [1,2], sternum [3], ribs [4,5], first cervical vertebra [6], patella [7], metacarpals and metatarsals [8,9], tarsals [10,11], and phalanges [9,12,13]. Among these, the metacarpals have received considerable attention in the forensic literature [9,12,14–20], perhaps because metacarpal bones have dense cortices and are relatively resistant to taphonomic processes [21]. These characteristics make them good candidates for metric sex determination when the larger bones of the skeleton are absent or damaged. In Thailand, metric methods of sex determination have been developed for several parts of the skeleton including the femur [22], humerus [23], sternum [24], vertebrae [25] and radius [26]. However, no previous studies have been published on sexing from the metacarpals. The purpose of this study is to add to our understanding of sexual dimorphism in human metacarpals, and to create accurate formulae for sexing of Thai individuals from measurements of the metacarpals. 2. Materials and methods The sample selected for this study consists of 250 skeletons of Thai adults (155 males, 95 females) from the Chiang Mai University Skeletal Collection housed at the Forensic Science International 217 (2012) 229.e1–229.e8 A R T I C L E I N F O Article history: Received 20 May 2011 Received in revised form 15 October 2011 Accepted 24 October 2011 Available online 21 November 2011 Keywords: Sex determination Hand Metacarpal ROC analysis Thailand A B S T R A C T Determination of sex using metacarpals was carried out on a sample of 249 skeletons from a Thai population (154 males and 95 females), ranging in age from 19 to 93 years. Six measurements were taken on each metacarpal, namely maximum length, medio-lateral base width, antero-posterior base height, medio-lateral head width, antero-posterior head height and mid-shaft diameter. Binary logistic regression equations were calculated for determining sex from these measurements. All metacarpals from both sides produced at least one equation that correctly allocated the skeletons with 80% or greater accuracy. In a comparative test using only individuals with no missing measurements (n = 196), the most accurate equations for each metacarpal on the right side had pooled allocation accuracies ranging from 85.2% to 89.3%, with the best equation based on three measurements from the 5th metacarpal. On the left side, the most accurate equations for each metacarpal ranged from 83.2% to 89.8% correct allocation, with the best equation based on three measurements of the 2nd metacarpal. When the allocation accuracy for each sex is considered in addition to the pooled accuracy, the best equations involve the same three measurements of the 5th metacarpal on the right side, but shift to three measurements of the first metacarpal on the left side, with a pooled accuracy of 88.3%. The results of this study suggest that metacarpals can be used quite reliably for sexing in forensic contexts in Thailand. ß 2011 Elsevier Ireland Ltd. All rights reserved. * Corresponding author. Tel.: +66 053945312; fax: +66 035945304. E-mail addresses: pasuk034@gmail.com, pmahanka@mail.med.cmu.ac.th (P. Mahakkanukrauh). Contents lists available at SciVerse ScienceDirect Forensic Science International jou r nal h o mep age: w ww.els evier .co m/lo c ate/fo r sc iin t 0379-0738/$ – see front matter ß 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.forsciint.2011.10.044