Abstract:

Traditional fingerprint classification systems exhibit limitations in the precise categorization and biological interpretation of special or complex fingerprint morphological features, thereby hindering the interdisciplinary research and applications of fingerprints. This study introduces a systematic framework for leaf-like patterns (LLPs), encompassing four subtypes: semi-leaf loops, full-leaf loops, semi-leaf whorls, and full-leaf whorls. Using data from 161 families (626 individuals) in northeastern China, we conducted morphological observations and statistical analyses to investigate the morphological principles, inheritance patterns, and evolutionary mechanisms of LLPs. Following standard dermatoglyphic research protocols, high-resolution (1,000 dpi) ink-rolled fingerprints were collected, and samples with congenital anomalies or distortions were excluded. Statistical analyses included Kolmogorov-Smirnov testing, Pearson correlation analysis, and multivariate regression modeling to quantify parental contributions to LLP expression in offspring. Key findings include: 1) LLPs accounted for 12.00% of loops and 19.28% of whorls. Notably, LLPs were concentrated on the ring finger, occurring approximately 1.93 times as frequently as on other digits. 2) Maternal lineage may play a relatively prominent role in the transmission of LLPs. Maternal-offspring correlations (r=0.227, P<0.01) and the explanatory power of the regression model (adjusted R²=0.046) significantly surpassed paternal contributions. Multivariate regression models further confirmed maternal dominance, with maternal regression coefficients (β=0.130 to 0.268) consistently exceeding paternal values (β=0.095 to 0.113) across offspring groups. 3) Comparative analysis of fingerprint ridge counts revealed that the morphological complexity of LLPs is intermediate between non-leaf loops (loops excluding semi-leaf and full-leaf loops) and non-leaf whorls (whorls excluding semi-leaf and full-leaf whorls). Analysis of isogeneic combinations revealed a marked affinity for LLP homotypic pairs (LLP/LLP observed frequency was about 2.2-fold higher than expected, P<0.001), while allogeneic combinations with simpler fingerprint patterns (arches and non-leaf loops) displayed incompatibility. By proposing a novel taxonomic framework for fingerprint morphological features, we advance the systematic classification of dermatoglyphic diversity and shed light on its evolutionary mechanisms. The study of LLPs provides foundational insights in three areas: 1) A deeper understanding of population-specific fingerprint variation; 2) Refinement of fingerprint identification through LLP-specific pattern recognition algorithms and likelihood ratio estimation; 3) Potential correlations between LLP distributions and developmental disorders, which require further investigation. The methodological approach and empirical results contribute to the advancement of dermatoglyphic research in anthropology, forensic science, and medicine.

Key words: fingerprint classification, inheritance pattern, evolution of fingerprint, anthropology, dermatoglyphics