Discriminant function analysis of craniometric data for distinguishing Japanese and Filipino crania

Abstract

Given their similar morphology and gene-flow histories, determining whether an unidentified cranium found in the Philippines is Japanese or Filipino presents a challenge. Two different analyses are undertaken. First, discriminant function (DF) analyses are applied to 295 crania using 22 measurements for distinguishing between: 1) males and females, 2) Japanese and Filipino males, and 3) Japanese and Filipino females, and 4) among four groups (Japanese males, Filipino males, Japanese females, and Filipino females). Second, a DF equation for distinguishing Japanese males and Filipino males using 173 crania and 29 measurements is introduced. In addition to being able to distinguish between Japanese and Filipino crania, this study found that seldom used cranial measurements such as simonic chord (least nasal breadth -WNB), inferior malar length (IML), and maximum malar length (XML) are influential for distinguishing between these two Asian groups. The predicted classification accuracy of DF equations from both analyses ranged from 82.0% to 93.6%. Sixty test crania for the first study and 40 for the second study maintains classification success rates between 82.0% and 93.3%. The DF equations reported in this study can be a useful initial screening tool for identifying Japanese war dead in the Philippines.