Sex estimation from skeletal remains is an important practice for forensic human identification. The aims of this study were to assess sexual dimorphism and to develop discriminant function equations for sex estimation using 12 measurements of upper limb bones (humerus, ulna, and radius) in a Thai population. The sample consisted of 228 Thai skeletons (114 males and 114 females) from the Forensic Osteology Research Center, Chiang Mai University, Chiang Mai, Thailand. All skeletal length variables were measured according to the Standards for Data Collection from Human Skeletal Remains. The values of measurements were used to develop the sex estimation equations using univariate and multivariate discriminant function analyses. The results of sexual dimorphism showed that upper limb bone lengths of males were statistically significantly longer than those of females in all dimensions (P<0.05). For univariate discriminant function analysis, the results showed that the epicondylar breadth of the humerus, the physiological length of the ulna, and the antero-posterior diameter at the midshaft of the radius were the best indicators for sex estimation in the humerus, ulna, and radius, respectively. Moreover, the multivariate discriminant function equation using all variables of the ulna and radius was the best indicator for sex estimation. In conclusion, the discriminant function equations derived from upper limb bone measurements provided highly accurate sex estimation in Thai samples. Therefore, these equations using humerus, radius, and ulna measurements can be applied for sex estimation with good accuracy in Thais.

Sex determination is an important step in biological identification from skeletal remains, especially in forensic circumstances. Many authors suggested that the morphological study was more subjective than the metric. There are various craniometric studies in different populations. They revealed that there was population-specific for the sex discriminant equation derived from each population. Thus, the present study aimed to evaluate sexual dimorphism and develop the discriminant function from 200 Thai skulls. Twenty-five standard cranial measurements were examined. The results revealed that males' cranium were statistically significant larger than females' in all measurements (P<0.05), except for minimum breadth of nasal bone. Sexual dimorphism index also expressed relatively high male/female ratio indicating great sexual dimorphism. The best practical equation for sex determination with six measurements (maximum cranial length, bizygomatic breadth, biauricular breadth, nasal height, biorbital breadth and right mastoid length) was derived from a stepwise discriminant method. This equation with 90.6% accuracy (91.1% in male and 90.0% in female) can provide valuable application utilizing in sex determination from skull in a Thai population.
Asian Continental Ancestry Group* ; Cephalometry ; Humans ; Male ; Mastoid ; Nasal Bone ; Skull