Esperanza Gutiérrez-Redomero

Sex differences in fingerprint ridge density in the Mataco-Mataguayo population

Ridge density (RD), the number of digital ridges per unit area, varies according to sex, age, and population origin. The main objective of this study was to determine the extent of sexual dimorphism in RD and to set the age at which it appears, in an Amerindian sample from the Mataco-Mataguayo population. The sample studied for this research consisted of 99 males and 110 females, between 6 and 25 years old, which amounts to a total of 2090 fingerprints. Ridge count was carried out on distal radial and distal ulnar and on proximal regions of each finger to explore the RD patterns in order to identify similarities and differences among samples, areas, age groups, and sexes. RD decreased with age and, at all ages, RD was higher on the distal (radial and ulnar) areas, followed by the proximal sides. Females were found to have higher RD than males when older than 12 years, but not when younger. In the radial area, the Mataco-Mataguayo population, in both sexes, presented the RD similar to Spanish samples, but higher than all other populations analysed to date using this method. Variations in RD in the Amerindian population based on sex, age, and topology were confirmed in this work, and it is postulated that these variations are due to developmental differences among individuals and populations. A comparison between the Mataco-Mataguayo and Spanish populations is presented.

Distribution of the minutiae in the fingerprints of a sample of the Spanish population.

One of the fundamental aspects of the process of identification through fingerprints is the comparison of the minutiae between the fingermark obtained at the scene of the crime and the suspects corresponding finger. There is no scientific basis in this process that allows the use of numerical standards, such as those kept in different countries, to obtain the identification. The recent mistakes made in the field of dactyloscopy, together with the growing rigor and scrutiny that forensic evidence undergoes in the legislative and scientific areas, have resulted in the need to reconsider some of the basic principles that support this discipline. A probabilistic estimation of the evidential value is especially necessary; therefore, it is indispensable to know and quantify the variability of the features used in the identification process. The sample studied for this research was obtained from 100 Caucasian men and 100 Caucasian women from the Spanish population, which amounts to a total of 2000 fingerprints. The different types of minutiae were located, identified, and quantified visually on the fingerprint, in four sectors, and inside and outside of a circle, whose radius cut, perpendicularly, fifteen ridges starting from the center cut of the axes that defined the sectors. According to the results obtained in this study, through dactyloscopic identification, the weight of the evidence of a minutia, such as the ridge endings, with frequencies between 55% and 65%, according to the area and gender evaluated, cannot be the same as that of a bifurcation or convergence, with frequencies of 13-18% or those of other minutiae that show frequencies lower than 3%. The significant differences found in the topological distribution of the endings, bifurcations, and convergences show the need to take into account, for its demonstrational value, the finger area in which they are evaluated. The significant association observed between the types of minutiae and the different fingers revealed a greater frequency of endings on the thumb and index fingers, and bifurcations and convergences on the middle, ring, and little fingers.

Topological Variability of Fingerprint Ridge Density in a Sub‐Saharan Population Sample for Application in Personal Identification

Variability in ridge density in a sub‐Saharan population sample was studied by counting ridges in three fingerprint areas (two distal regions, radial and ulnar, and one proximal region) on the epidermal surface of the distal phalanx. Study material was obtained from the fingerprint impressions of 100 male sub‐Saharan subjects aged between 18‐ and 48‐years old. The results were compared with those obtained from a Spanish population sample. Sub‐Saharan males presented lower ridge density than Spanish males in the distal regions (radial and ulnar) of all fingers, whereas differences in the proximal region were only observed on some fingers. Using the differences observed between these populations, the likelihood ratio for inferring membership of one of the populations from a fingerprint of unknown origin was calculated; therefore, a ridge density of 14 or less for both areas (ulnar and radial), support an origin sub‐Saharan versus Spanish population.

Assessment of the methodology for estimating ridge density in fingerprints and its forensic application

In recent times, some studies have explored the forensic application of dermatoglyphic traits such as the epidermal ridge breadth or ridge density (RD) toward the inference of sex and population from fingerprints of unknown origin, as it has been demonstrated that there exist significant differences of fingerprints between sexes and between populations. Part of the population differences found between these studies could be of methodological nature, due both to the lack of standardisation in the position of the counting area, as well as to the differences in the method used for obtaining the fingerprint. Therefore, the aim of this study was to check whether there are differences between the RD of fingerprints depending on where the counting area is placed and how the fingerprints are obtained. Fingerprints of each finger were obtained from 102 adult Spanish subjects (50 females and 52 males), using two methods (plain and rolled). The ridge density of each fingerprint was assessed in five different areas of the dactylogram: two closer to the core area (one on the radial and the other on the ulnar side), two closer to the outermost area of each of the sides (radial and ulnar), and another one in the proximal region of the fingertip. Regardless of the method used and of the position of the counting area, thumbs and forefingers show a higher RD than middle, ring, and little fingers in both sexes, and females present a higher RD than males in all areas and fingers. In both males and females, RD values on the core region are higher than those on the outer region, irrespective of the technique of fingerprinting used (rolled or plain). Regardless of the sex and location of the count area (core or outer), the rolled fingerprints exhibit RD greater than that of the plain ones in both radial and proximal areas, whereas the trend is inverted in the ulnar area, where rolled fingerprints demonstrate RD lesser than that of the plain ones. Therefore, in order for the results of different studies to be comparable, it is necessary to standardise the position of the count area and to use the same method of obtaining the fingerprint, especially when involving a forensic application.

Are there population differences in minutiae frequencies? A comparative study of two Argentinian population samples and one Spanish sample

In recent years, both scientific and judicial sources have highlighted the need for more knowledge about minutiae variability, in order to improve their statistical application to fingerprint identification. In line with this trend toward improving our knowledge of this subject, the aim of the present study was to calculate the frequency with which 20 types of minutiae appeared in 2780 fingerprint impressions obtained from 278 individuals from two Argentinian population samples (100 individuals from Ramal and 178 from Puna-Quebrada). The different types of minutiae were located, identified, and quantified visually in two areas on the fingerprint, the inside and outside of a circle, the radius of which cut fifteen ridges perpendicularly, starting from the center cut of the axes defining the sectors. The non-equiprobability found in both population samples for the different minutiae types studied demonstrated that the evidential weight provided by these characteristics is not the same when applied in identification processes, whether used quantitatively (numerical standard) or qualitatively (holistic method). The results obtained for both populations were compared statistically with those published previously for a Spanish population sample, which had been collected using the same methodology. This comparison has enabled us to demonstrate, for the first time, the existence of significant differences between populations in minutiae frequencies, independently from the main pattern type.

Sexual and topological differences in palmprint and ridge density in the caucasian Spanish population.

Despite the fact that variation in ridge breadth is of biological, medical, and genetic interest, it has not received as much attention as other dermatoglyphic characteristics. Recently, sex differences in mean epidermal ridge breadth have been proposed in the field of forensic identification in order to infer gender from fingerprints found at the scene of a crime left by an unknown donor. The aim of this research was to analyze sexual, bimanual, and topological variations in epidermal ridge breadth on palmprints taken from a Spanish population sample for subsequent application in inferring gender from the palm marks. The material used in the present study was obtained from the palmprints of 200 individuals (100 males and 100 females) from the Caucasian Spanish. Since ridge breadth varies according to age, subjects of similar ages were recruited to ensure that growth had finished. Therefore, in order to assess topological variation in ridge density or number of ridges in a given space, the count was carried out for the five palmar areas: hypothenar, thenar/first interdigital, second interdigital, third interdigital, and fourth interdigital. This allowed the segmentation of 2000 ridge count areas for analysis. For this, two methods were used, one described by Cummins et al. (the ridge count was carried out along a 1cm line) and the other by Acree (the number of ridges per 25 mm(2) of surface area). The results obtained by the second method can be compared with those obtained for the ten fingers from this same sample and evaluated in a previous study. The results have demonstrated the existence of topological differences in ridge thickness on the epidermal palm surface; also females present a significantly higher ridge density than men and, therefore, have narrower ridges over the entire palmar surface. Those sexual differences found in the sample population can be used for inferring the gender from palm marks left by an unknown donor. The hypotheses that could explain the variability in ridge breadth are evaluated according to the obtained results.

Surnames, geographic altitude, and digital dermatoglyphics in a male population from the province of Jujuy (Argentina)

The possible association between finger dermatoglyphic patterns and altitude and surname distribution was analyzed in a sample of adult males from the province of Jujuy, Argentina. We also investigated the biological affinity of this population with other South American natives and admixed populations. Fingerprints were obtained from 996 healthy men, aged 18-20 years, from the highlands (HL: 2500m, Puna and Quebrada) and lowlands (LL: Valle and Selvas). Surnames were classified into native/autochthonous (A) or foreign (F), resulting in three surname classes: FF, when both paternal and maternal surnames were of foreign origin; FA, when one surname was foreign and the other was native; and AA, when both surnames were native. Frequencies of finger dermatoglyphic patterns - arches (A), radial loops (RL), ulnar loops (UL), and whorls (W) - were determined for each digit in relation to geographic location, altitude, and surname origin, resulting in the following categories: HL-FF, HL-FA, HL-AA, LL-FF, LL-FA, and LL-AA. The statistical analyses showed that UL and RL were more common in individuals of HL origin, whereas W and A were more frequent in the LL males (p<0.05). Significant associations were observed between finger dermatoglyphic patterns and surname origin when geographic altitude was considered. In the HL group, UL was associated with AA and FA; in the LL group, the presence of A was associated with FF and FA. The distribution of dermatoglyphic patterns shows that the population of Jujuy belongs to the Andean gene pool and that it has undergone differential levels of admixture related to altitude.

Study of fingerprints in Argentina population for application in personal identification

The fingerprints of the Buenos Aires and Chubut provinces in Argentina have been studied, with the aim of knowing and quantifying the variability of these features, which are used in the identification process. The data studied for this research was obtained from 330 individuals, of both sexes, from two Argentinian population samples (170 individuals from Buenos Aires and 160 from Chubut), which amounts to a total of 3300 fingerprints. The different types of minutiae were located, identified, and visually quantified in four areas on the fingerprint. Two perpendicular axes were drawn whose intersection was located in the center of fingerprint. In addition, a circle was defined on these quadrants whose radius cut fifteen ridges. This method divides the fingerprints into four quadrants with two sectors apiece. The results obtained for both populations were compared statistically with those published previously for an Argentinian population sample, which had been collected using the same methodology. Therefore, Argentina becomes the country with the most information in this matter. For both populations, the highest frequencies were of ridge endings, followed by bifurcations and convergences. In this study of minutiae, statistically significant differences were found between the area of the fingerprint (inside and outside the circle), males and females, and types of main pattern for both samples. However, although the results show common patterns in the distribution of minutiae, there are also significant differences between populations. This reveals a significant ancestral and frequency effect of the minutiae, which would indicate that the minutiae are more genetically dependent than has been suspected so far. Furthermore, the non-equiprobability found for the frequency of the types of minutiae indicates that the weight provided by these characteristics is not the same when applied in identification processes, whether used quantitatively (numerical standard) or qualitatively (holistic method).

The asymmetry of dermatoglyphic finger ridge counts and the geographic altitude of the Jujenean population in northwest Argentina

Asymmetry is omnipresent in the living world and therefore is a measure of developmental noise and instability. The main stressing agent in high-altitude ecosystems is hypobaric hypoxia. The variation in bilateral dermatoglyphic symmetry in populations from the Province of Jujuy in northwest Argentina is analyzed, and these results are compared to those for other populations with different ethnic and environmental backgrounds. Fingerprints were collected from 310 healthy students (140 males and 170 females) aged 18-20 years from three localities in Jujuy Province-Abra Pampa (3484 m above sea level), Humahuaca (2939 m above sea level), and San Salvador de Jujuy (1260 m above sea level). Asymmetry by sex was assessed based on radial and ulnar ridge counts to determine its pattern of variability (directional asymmetry [DA], fluctuating asymmetry [FA] and antisymmetry), and asymmetry and diversity indices were calculated. A bivariate plot and principal component analysis (PCA) were used to compare these indices with those for other populations. Homogeneity was found between populations and sexes when radial and ulnar ridges were counted. FA values did not show significant differences by locality or side (ulnar and radial), but significant differences were found by finger and sex, with males showing significantly greater FA values. The asymmetry and diversity indices clearly group the Andean populations and separate them from populations of different ethnic and geographic origin. Only the diversity index showed significant differences by locality in males, which suggests a substantially different genetic component in Abra Pampa male samples.

Diversity of human lip prints: a collaborative study of ethnically distinct world populations

Abstract Background: Cheiloscopy is a comparatively recent counterpart to the long established dactyloscopic studies. Ethnic variability of these lip groove patterns has not yet been explored. Aim: This study was a collaborative effort aimed at establishing cheiloscopic variations amongst modern human populations from four geographically and culturally far removed nations: India, Saudi Arabia, Spain and Nigeria. Subjects and methods: Lip prints from a total of 754 subjects were collected and each was divided into four equal quadrants. The patterns were classified into six regular types (A–F), while some patterns which could not be fitted into the regular ones were segregated into G groups (G-0, G-1, G-2). Furthermore, co-dominance of more than one pattern type in a single quadrant forced us to identify the combination (COM, G-COM) patterns. Results and conclusion: The remarkable feature noted after compilation of the data included pattern C (a bifurcate/branched prototype extending the entire height of the lip) being a frequent feature of the lips of all the populations studied, save for the Nigerian population in which it was completely absent and which showed a tendency for pattern A (a vertical linear groove) and a significantly higher susceptibility for combination (COM) patterns. Chi-square test and correspondence analysis applied to the frequency of patterns appearing in the defined topographical areas indicated a significant variation for the populations studied.