The Variation of Ridge Density in Palm Prints among Nigerian Ethnic Populations and its Forensic Use for Sex Determination

Abstract

Friction ridge skin has unique features that persist from before birth until decomposition after death. Finger and palm print identification is based on two primary factors: uniqueness and permanence. Ridge density (ridge count in a defined area) has been explored for its applicability in inference of sex from the fingerprints and palm prints recovered at the crime scene. In this study, we examined the variability of palm ridge density (PRD) from palm prints among Hausa, Igbo and Yoruba ethnic groups and its ability to infer sex in forensic examinations. The sample consisted of bilateral palm prints of 560 healthy adults (251 females and 309 males) from three ethnic groups in southwestern states. The prints were manually analyzed in four defined areas (PRD-1, PRD-2, PRD-3 and PRD-4) and the values aggregated. The ethnic and sex differences in palm print ridge densities were statistically analyzed for each of the designated areas. The mean (SD) aggregate PRD values of 11.49(1.48) for Hausa, 10.75(1.46) for Igbo and 11.71(1.64) for Yoruba; were significantly different (p<0.05) between the ethnic groups and significantly greater (p<0.05) in females than in males; 11.71(1.53) vs 9.93(1.02). The aggregate mean (SD) ridge densities were also significant different (p<0.05) between the right and left hands 11.09(1.05) and 9.33(1.14) respectively. This study showed significant differences in palm ridge densities among Nigerian major ethnic groups. There are also gender, right and left hand differences in this dermatoglyphic parameter. These results have forensic implications.