Variability in human external ear anthropometry- Anthropological and forensic applications.
Abstract The human auricle has attracted the attention of forensic scientists since a long for its unique morphological characteristics. In modern times, these unique features can be captured by CCTV cameras, which may be extremely useful during the identification process in a criminal investigation. Unique morphological characteristics such as Darwin's tubercle, shape, and size of the ear, different morphological features of the helix, tragus, lobule, etc. are frequently used in the identification and individualization process. The human ear was not only accessi-ble for its morphological and morphometric variations, but also its existing bilateral, sex, and population differences. The present study was conducted on 140 individuals (71 males and 69 females) aged between 18 and 30 years. The data were collected from the colleges of Nahan city of Sirmaur district in Himachal Pradesh state of North India. Various anthropometric measurements were taken independently on the left and right ear of each individual with the help of a pair of sliding calipers using a standard method. These linear measurements were physiognomic ear length, physiognomic ear breadth, ear length above tragus, distance from tragus to antihelix, distance from tragus to the helix, lobule height, and lobule width. Auricular index, lobular index, and lobular ear index were calculated from the aforementioned measurements. Further, an independent t-test/ Mann Witney U test and paired sample t-test/ Wilcoxon Signed Rank test were applied for the evaluation of sex differences and bilateral differences in the human ear, respectively. For the prediction of sexual dimorphism, discriminant function analysis was applied. Physiognomic ear length, physiognomic ear breadth, ear length above tragus, distances from tragus to antihelix (left ear only), and tragus to helix exhibited significant sex differences on both sides (p<0.05). Significant bilateral differences (p<0.05) were reported for all the measurements of the ear in males except for lobule height, whereas, significant side differences (p<0.05) were shown for ear length above tragus, distance from tragus to helix, and lobule width among females. The discriminant function model showed 82.10% accuracy for determining sexual dimorphism. The study highlighted sexual dimorphism and bilateral differences in ear morphometry in a north Indian population and provided a database of anthropometric variables in the human ear for forensic and anthropological uses.