Sex differences in frequencies of dermatoglyphic patterns by individual fingers

Sex differences in radioulnar contrasts of the finger ridge counts across 21 human population samples

Aim: The aim of the present study was to demonstrate the existence of uniform sexual dimorphism in some radioulnar contrasts between different finger ridge counts within the same hand in a large set of populations, thus confirming the universal nature of this dimorphism in humans.Subjects and methods: We analysed individual finger ridge counts (10 values on each hand) of both hands from archival sources (mainly the Brehme-Jantz database). In total, these included 4412 adults from 21 population samples covering all permanently inhabited continents and encompassing very different and geographically distant human populations. We calculated the contrasts (differences) of all pairs of ridge counts (45 per hand) and used diverse methods to assess the direction and degree of dimorphism of them across all population samples.Results: The highest sexual dimorphism was observed for nine contrasts involving the ridge count of the dermatoglyphic pattern on the radial side of the second finger of the right hand (R2r). Among these contrasts, we then found four that had the same direction of dimorphism in all 21 populations. The most dimorphic was the contrast R1rR2r - the difference between the ridge count of the radial side of the thumb and the radial side of the index finger.Discussion: Thus, these dermatoglyphic traits can be further investigated as potential markers of prenatal sex differentiation from ca. 10th week of intrauterine development. However, it will be useful to address the detailed factors and mechanisms for differences in the degree of dimorphism of these traits in different populations.

Distribution of different minutiae in thumbprint and its application to determine sex distinctions

Background

The present study is an attempt to explore the distribution of different minutiae in two topological areas of thumbprint and its application to determine sex distinctions.

Methods

For this purpose, a sample of 100 subjects (50 males and 50 females) ranging in age from 18 years to 25 years were taken from the Shimla (North India). A modified standardized method was adopted to count and classify 20 different types of minutiae.

Results

Findings of the study indicated that the frequency of thumbprint minutiae was higher among males than their female counterparts. Ridge endings were the most frequently occurring minutiae followed by bifurcation and convergence in both the sexes. No M-B was noticed among female participant, while negligible percentage (0.04%) of males exhibited M-B. The mean values of most of the minutiae were found to be higher in the outer circle than inner circle of the thumbprint in both the sexes. Lower frequency of ridge ending (< 20 for right hand and 31–40 for both right and left hand), convergence (< 10 for both right and left hand), and bifurcation (< 10 and 31–40 for right hand and < 20 for left hand) have higher probability of female origin. While higher frequency of ridge ending (> 60 for right hand and > 50 for left hand), convergence (> 20 for both right and left hand) and bifurcation (> 40 for right hand and > 30 for left hand) was more likely of male origin.

Conclusions

Findings of present study identified sex distinction in the distribution of minutiae with respect to the topological areas on the thumbprint.

Radioulnar contrasts in fingerprint ridge counts: Searching for dermatoglyphic markers of early sex development

OBJECTIVES

Using prenatally fixed dermatoglyphics features as markers of prenatal sex development is limited due to insufficient knowledge on their sex differences. This study aims to examine more thoroughly sex differences in radioulnar contrasts.

METHODS

Fingerprints of 360 females and 331 males from four samples of different ethnic backgrounds (Czechs, Slovaks, Vietnamese and Lusatian Sorbs) were studied. On both hands, finger ridge counts were recorded, and all possible radioulnar contrasts were computed as a difference between ridge count at a radial position minus ridge count at a respective ulnar position on the hand. Radioulnar contrasts with population-congruent and numerically large dimorphism were selected and the dimorphism of the selected radioulnar contrasts was then tested using nonparametric analysis of variance.

RESULTS

Greater dimorphism of radioulnar contrasts occurred on the right hand than on the left hand. Population congruent direction and relatively strong dimorphism (Cohen's d greater than 0.3) was found in six radioulnar contrasts on the right hand, all of which involved the radial ridge count of the 2nd finger. Of these, the highest average dimorphism was observed for the difference between the radial ridge count of the 2nd finger and the ulnar ridge count of the 4th finger (2r4u contrast), where the average effect size from all four population samples was comparable to a published average effect size of the 2D:4D finger length ratio.

CONCLUSION

We propose that 2r4u contrast of ridge counts could serve as a marker of prenatal sexual development targeting a temporally narrow developmental window.

Association between gestational period and obesity in children with the use of dermatoglyphic traits: A preliminary study

Events occurring during the gestational period can influence the development of diseases and conditions such as obesity. This study aimed to analyze the association between events occurring in the gestational period and the occurrence of obesity in children based on dermatoglyphic traits. The sample comprised 73 children born in 2009, living in Palhoça, Santa Catarina (SC), Brazil, regularly enrolled in public and private schools in that municipality and who are participants of an ongoing major cohort study project called Coorte Brasil Sul. The results show predictive traits of obesity when comparing BMI and fingerprint groups. Obese male group, presented the figure Ulnar Loop (UL) in the right hand (MDT1) thumb and greater number of ridges in the (MDSQL1) right thumb the greater the BMI; likewise, the older the woman getting pregnant the greater the number of ridges that the child presented in the (MESQL2) left index finger and (MESQL1) right thumb. The results obtained infer the presence of predictive traits of BMI ranges and a possible association between the dermatoglyphic traits of children with obesity and late pregnancy women.