Fingerprints, which are a result of dermal ridge morphogenesis during early prenatal development and are unchangeable throughout a person's life, have been used for personal identification in forensic science for a long time because of their reliability and the fact that each person has different ones (Acree, 1999; Krishan et al., 2013).

In addition to minutiae-based matching, there are quantitative dermatoglyphic traits such as ridge density, which is defined as the number of ridges present within a given area of 25 mm². These traits provide signals related to the population and the sex of an individual that are scientifically based on ridge width and spacing between ridges (Krishan et al., 2013; Oktem et al., 2015). Generally, across all the different cohorts, women show greater ridge density than men which is indicative of finer epidermal ridges and closer interridge distances, a pattern which has been seen in North Indian, Turkish, and Brazilian samples, among others (Acree, 1999; Krishan et al., 2013; Oktem et al., 2015; da Silva Carvalho et al., 2022).

Over time, comparisons have been problematic due to methodological discrepancies, with studies differing not only in the technique used for fingerprint taking (rolling or plain impressions) but also in the areas counted (the radial and ulnar areas next to the core or the more external or proximal regions). The authors propose obtaining better reproducibility and inter-study comparability through the standardisation of count area placement, which is typically two ridges above the core, and the consistent specification of the acquisition technique. This will also uncover the topological variation: distal (radial/ulnar) areas usually have higher ridge density than the proximal regions (Gutiérrez Redomero et al., 2014; Krishan et al., 2013). Rolled impressions can lead to an increase in radial counts when compared to plain prints due to distortion of the direction, while ulnar counts might reveal the opposite trend, stressing the importance of reporting method-specific effects in forensic applications (Gutiérrez Redomero et al., 2014).

1. One of the earliest attempts to use fingerprint ridge density for sex determination was made by Acree, M.A. (1999). The study was conducted on 400 individuals (200 males and 200 females) from Caucasian and African American populations aged between 18 and 67 years. Ridge density was measured in the radial area of fingerprints. The results clearly showed that females consistently had higher ridge density than males. Clear threshold values were proposed, where ridge density of ≤11 ridges per 25 mm² indicated male origin, while ≥12 ridges per 25 mm² indicated female origin. This study laid the foundation for establishing ridge density as a quantifiable forensic parameter for sex determination. (Acree, 1999)

2. In another study, the fingerprints of 200 North Indians belonging to 100 males and 100 females were analysed for ridge thickness/slope by Krishan K, Kanchan T, & Ngangom C (2013). The average ridge thickness/slope of the female subjects was found to be approximately 14-15 ridges/25mm², while for the male subjects, it was 11-12 ridges/25mm², with statistical significance of ‘p < 0.001’. (Krishan et al., 2013)

3. Kumar, L. et al. (2013) analysed the ridge density in the fingerprint patterns of 150 participants belonging to the Indian population, though the male-to-female ratio is not clearly mentioned. Females were found to have a greater ridge density compared to the males, ascertaining the presence of sexual dimorphism. (Kumar et al., 2013)

4. Gutiérrez-Redomero, E. et al. (2014) carried out a study of fingerprint ridge density in a population of over 300 people of both genders. They did not set the exact proportion of men to women. Marked sex-related disparities existed, and the consistency of the method was stressed rather than the sex-related means. (Gutiérrez-Redomero et al., 2014)

5. Kapoor, N. and Badiye, A. (2015) investigated the fingerprints of 200 Indian adults, roughly equal numbers of men and women. Women’s ridge density was found to be 1-2 ridges per 25 mm², more than those in men, although the male and female ridge counts were not detailed. (Kapoor & Badiye, 2015)

6. A study by Abdullah, S.F. and Rahman, A.F.N.A.R. (2015) involved the analysis of a group of 120 Malaysians, with 60 males and 60 females. The number of ridges that fall in the range of 13-15 for females and 10-12 for males indicates the variation among the population. (Abdullah & Rahman, 2015)

7. A research by Oktem, H. et al. (2015) carried out among 180 participants of Turkish origin—male and female among them, though the exact numbers are not provided—recorded a mean ridge density of 14.1 ± 1.2 among females and 11.8 ± 1.3 among males, which exhibited significant sexual dimorphism (Oktem et al., 2015).

8. Dhall, J.K. and Kapoor, A.K. (2015) investigated fingerprints of 150 North Indian participants, including males & females, but no detailed numerical representation. By discriminant function analysis, they obtained nearly 80% accuracy in gender determination. (Dhall & Kapoor, 2015)

9. Kumar, A.S. et al. (2017) carried out a regional study in the Uttarakhand region involving 100 people of both sexes, though the male and female numerosity wasn’t clearly mentioned. Females always showed a higher ridge density than males. (Kumar et al., 2017)

10. The study by Chauhan, A. (2017) assessed the fingerprints of the selected group of 80 individuals, which included both males and females. The females had a significantly higher density of the ridges. The number of subjects wasn’t adequate to form general conclusions. (Chauhan, 2017)

11. In a research study by Soe Htun, Kyaw & Hlaing, Khun & Zaw, Thein & Tin, & Hlaing, Tin. (2017), fingerprints were taken of 200 people belonging to the Southeast Asian population, including both males and females. The female subjects had greater ridge densities compared to males, even though they emphasised the significance of ethnic variations rather than mentioning a fixed value. (Htun et al., 2017)

12. In this study by Sucharitha, T.M., Phanindra, S.V., and Shaik, A.B. (2021), the ridge density tested in 120 Indian participants was not clearly male or female. For the female gender, the ridge density is higher with 70% predictability. (Sucharitha et al., 2021)

13. In their study, the fingerprint characteristics of 200 Brazilians, both male and female, were observed by da Silva Carvalho, D. et al. (2022). The average ridge values varied from 15/25mm² for females to 12 to 13/25mm² for male fingers, with the establishment of population-specific standards. (da Silva Carvalho et al., 2022)

14. Recently, Kandel, J., Ghimire, S. and Bhandari, R. (2023) conducted a study on the fingerprint ridge density of a sample size of 150 individuals from both sexes and reported a moderate accuracy on the determination of sex. While females have a higher ridge density, detailed male–female numerical means are not emphasised. (Kandel et al., 2023)

15. A study conducted by Sreekumar, B., Pannag, S. and Fernandes, A. (2023) concentrated more on the forensic viability of fingerprint ridge density values rather than precise numerical figures. The research evaluated around 100 fingerprint samples from both males and females to determine the potential of ridge characteristics to identify sexes during forensic analyses. (Sreekumar et al., 2023)

16. A study by Gokulakrishnan, R. et al. (2024) involved 180 South Indians. Both males and females participated in the study. A statistically significant sexual dimorphism in the density of the epithelial ridges with overlapping ranges for males and females was observed. (Gokulakrishnan et al., 2024)

17. Ibrahim, B.M. et al. (2024) on their part, investigated the fingerprint ridge density among a population of 100 students belonging to the Hausa ethnicity, with 50 of them being male and 50 females. The results of their research indicated a higher fingerprint ridge density among females compared to males, thus establishing sexual dimorphism alongside standards among different groups of ethnicity. (Ibrahim et al., 2024)

18. R, P., S, S. and RS, S. (2025) conducted their experiment on 120 fingerprint samples from males and females using stereomicroscopic techniques for analysis. The efficiency of such advanced techniques can be estimated from the accuracy rate for predicting sex, which has been reported to be over 80%. The usage of these techniques has remained rudimentary due to equipment needs. (R et al., 2025)

19. Abdu, Habibu Maaruf & Nabegu, Zainab & Umar, Fatima & Mahmud, Zainab & Sulaiman, Shehu. (2025) analysed the ridge density of the fingerprints of the African community comprising over 200 individuals of both sexes. The ridge density of females was found to be higher compared to males, but to some extent, they were similar. The lack of proper values for ridge density and the requirement for preparation of databases as per the population were pointed out. (Abdu et al., 2025)