PAPER ANTHROPOLOGY Drosia Charisi, 1 B.Sc.; Constantine Eliopoulos, 1,2 Ph.D.; Velissaria Vanna, 3 M.Sc., M.St.; Christos G. Koilias, 4 Ph.D.; and Sotiris K. Manolis, 1 Ph.D. Sexual Dimorphism of the Arm Bones in a Modern Greek Population ABSTRACT: Several studies have shown that sex determination methods based on measurements of the skeleton are population specific. Metric traits of the long bones of the arm have been reported as reliable indicators of sex. This study was designed to determine whether the three long bones of the arm can be used for sex determination on a skeletal population from Greece. The material used consists of the arm bones of 204 adult individuals (111 males and 93 females) coming from the Modern Human Skeletal Collection of the University of Athens. The age range is 19–96 years for males and 20–99 years for females. The maximum lengths and epiphyseal widths were measured in the long bones of the arm (humerus, radius, and ulna). The discriminant analysis of the metrical data of each long bone gave very high discrimination accuracies. The rate of correct sex discrimination based on different long bones ranges from 90.30% (ulna) to 95.70% (humerus). In addition, intra- and inter-observer error tests were performed. These indicated that replication of measurements was satisfactory for the same observer over time and between observers. The results of this study show that metric characteristics of the arm bones can be used for the determination of sex in skeletal remains from Greece and that bone dimensions are population specific. KEYWORDS: forensic science, sex determination, discriminant function, humerus, radius, ulna Sexual dimorphism, as a characteristic of living organisms, and its different forms of expression is a topic that has attracted the interest of many researchers. According to a general definition, ‘‘sexual dimorphism is the development of visible morphological differences between males and females in a species or population.’’ A more specific definition in reference to the human species is that by Relethford (1), according to which sexual dimorphism is the average difference in body size between male and female adult individuals. The main dimorphic characteristic of primates, which is evident in humans, is body size. The general rule in the animal kingdom is that the female is the larger of the two sexes (2). In mammals and birds, however, the opposite is true, with few excep- tions. It is believed that the smaller size allows females to make a better use of the energy required for developing a greater body mass. Instead, the energy is used for the creation of offspring through processes, such as gestation and nursing (2). In humans, the trait most indicative of sexual dimorphism is stat- ure. The fact that on average males are taller than females is com- mon across all human populations (3,4). This is attributed to the different rate of growth in the lower limbs and not the torso (5). Body size in males has been estimated to be 8–20% larger than that of females (6,7). Sexual dimorphism is present in the human skeleton as well. In many skeletal elements, it is present in the form of shape differences, while in others it is only the result of size variation. According to Plavcan (6), sexual dimorphism in the skeleton of primates is related to overall body size differences. Therefore, the human skeleton displays sexually dimorphic charac- teristics that are expressed by larger and more robust bones in males (7,8). These differences become evident only after the end of puberty, when the skeleton has completed its growth (9). A large number of studies have demonstrated that there is varia- tion in the degree of sexual dimorphism among different popula- tions (4,10,11). This variation is related to body size and consequently to metric differences in the dimensions of individual skeletal elements (12–17). In addition, sexual dimorphism is present not only between populations, but within populations as well. Many factors contribute to sexual dimorphism in a population; however, the most important is believed to be its genetic composition (3,10,18). It has been observed that the size of bones is determined genetically, although not in the same manner in different popula- tions. For example, a team of researchers has located a chromo- somal area thought to be responsible for the variation in the size of the femur and vertebrae between different populations (19). The above observation in combination with the fact that the genes that determine bone size interact with sex genes (18) suggest that sexu- ally dimorphic changes have a strong genetic basis. Another very important factor affecting the expression of sexual dimorphism is the environment, especially diet (12,20–22). An acute environmental stress, e.g., malnutrition, usually leads to a reduction of sexual dimorphism. However, once optimal conditions have been restored males tend to grow faster than females, leading 1 Department of Animal and Human Physiology, Faculty of Biology, School of Sciences, University of Athens, Panepistimiopolis, GR 157 01 Athens, Greece. 2 Research Centre in Evolutionary Anthropology and Palaeoecology, School of Natural Sciences and Psychology, Liverpool John Moores Univer- sity, Byrom Street, Liverpool L3 3AF, U.K. 3 Institute of Archaeology, University College London, 31-34 Gordon Square, WC1H 0PY, London, U.K. 4 Department of Informatics, Technological Educational Institute of Ath- ens, Aghiou Spyridonos, Egaleo, GR 122 10 Athens, Greece. Received 10 July 2009; and in revised form 12 Oct. 2009; accepted 23 Oct. 2009. J Forensic Sci, 2010 doi: 10.1111/j.1556-4029.2010.01538.x Available online at: interscience.wiley.com Ó 2010 American Academy of Forensic Sciences 1