Sex differences in the thumbprint ridge density in a central Indian population

Abstract

Background: Identification of sex plays a vital role in forensic and medico legal investigations. Fingerprints are considered to be the most precise and reliable indicators for personal and gender identification. Objectives: The objective of this study was to determine any significant difference in the thumbprint ridge density of males and females in a central Indian (Marathi) population to enable the determination of gender. Methods and materials: The study was conducted on 200 subjects (100 males and 100 females) in the age group of 18–30 years. Ridge densities on the right- and left-hand thumbprints were determined using a newly designed layout and analysed statistically. Results: The results showed that females tend to have a higher thumbprint ridge density in both the areas examined, individually and combined. Applying the t-test, the differences in the ridge densities of males and females at LoC (Left of Centre), RoC (Right of Centre) and Combined (LoC + RoC) were found to be statistically significant at p < 0.01 levels, proving the association between gender and fingerprint ridge density. Probability densities for men and women derived from the frequency distribution (at LoC, RoC and Combined) were used to calculate the likelihood ratio and posterior probabilities of gender designation for the given ridge count for subjects using Baye’s theorem. Conclusion: It was concluded that differences in the thumb ridge density can be used as an important tool for the determination of gender in cases where partial thumbprints are encountered as evidence either at the crime scene or on any document(s) of forensic significance.

Keywords

• Thumbprints
• Thumbprint ridge density
• Gender identification
• Fingerprint ridge density
• Forensic identification