A comparative study of topological and sex differences in fingerprint ridge density in Argentinian and Spanish population samples.

Although several studies have recently assessed sex differences in fingerprint ridge density and its variability in human populations from different origins, such a study has not been carried out yet in the Amerindian population. The goal of this study was to determine the topological and sexual differences in fingerprint ridge density (RD) in native subjects from two samples of northwestern Argentina (Jujuy province) living at different altitudes. The results were compared with those obtained from a Spanish population sample. The study was based on data from all 10 fingerprints of 393 adult Argentinian men and women, 193 from the Puna-Quebrada region (more than 2500 m above sea level) and 200 from Ramal (500 m above sea level). Ridge density was assessed for three different areas (radial, ulnar and proximal) for all 10 fingers of each subject. In both samples, significant differences between areas were obtained, so radial RD > ulnar RD > proximal RD. No significant differences were found between samples in males, while females from both samples significantly differed in the radial and proximal areas. Females have higher RD, so narrower ridges, than men, in all areas and all fingers. Application of Bayes' theorem allowed us to obtain a ridge density threshold for discrimination of sexes in Argentinian samples and the threshold for discrimination of populations between Argentinian and Spanish samples. These results can be useful for forensic use.