SEXUAL DIMORPHISM IN FINGERPRINT RIDGE DENSITY: A STUDY IN SURABAYA, INDONESIA

Fingerprints are considered the primary human identifier and a gold standard in forensic identification. However, the application of fingerprints for sex estimation in Indonesia remains limited. This study aimed to evaluate sex-related differences in fingerprint ridge density among young adults and to develop a population-specific discriminant formula for sex classification. Fingerprints of all ten digits were collected from 90 participants (45 males and 45 females), aged 17–21 years. Fingerprints' ridge density was quantified in three anatomical regions (radial, ulnar, and proximal) and statistically analyzed using SPSS version 23.0. Discriminant function analysis was employed to identify the most informative digits for sex prediction and to develop a predictive classification model. The present study found that females consistently exhibited significantly higher ridge densities than males across all ten digits (p < 0.001). Four digits—the right thumb, right index finger, right little finger, and left index finger—were identified as the most reliable predictors for sex differentiation. The derived discriminant function achieved an overall classification accuracy of 97.2% in cross-validation and 94.4% in the test sample. These findings confirm that fingerprint ridge density is a robust indicator for sex estimation in the Surabaya population. This study highlights the importance of developing population-specific sex-determination formulas for forensic identification. Further studies with larger, more diverse samples are recommended to validate and improve the generalizability of this model for routine forensic casework.