Exploring Facial Index as an Indicator of Ethnic Lineage in Upper Himalayan Indigenous Tribal Populations

Facial features differ widely among individuals and populations, shaped by a mix of biological and environmental influences. These differences can be observed between groups from various regions and even within communities living in the same area. The Facial Index (FI) is commonly used to compare facial proportions across different populations.

This study aims to estimate the FI, classify facial types based on FI, evaluate sexual dimorphism, and generate reference data on facial morphology. The study also aimed to compare FI values with those of other populations.

A total of 413 individuals participated in the study, comprising 247 (59.8%) male participants and 166 (40.2%) female participants, aged 18-50 years, from the tribal districts of Kinnaur, Lahaul, and Spiti. Facial measurements were recorded using standard anthropometric tools, and the FI was calculated. Data were analyzed using IBM SPSS Statistics software version 27 (IBM Corp., Armonk, NY).

The mean values of morphognomic facial length (MFL), bizygomatic breadth (BZB), and FI were 130.69 ± 8.09 mm, 112.81 ± 9.81 mm, and 116.42 + 9.31, respectively. Male participants exhibited significantly greater facial dimensions in terms of both MFL and BZB compared to female participants, but there was no significant difference in FI. The hyperleptoprosopic facial type was predominant, observed in 386 (93.5%) individuals, followed by 20 (4.8%) leptoprosopic, six (1.5%) mesoprosopic, and one (0.2%) euryprosopic types. Among male participants, 233 (94.3%) were hyperleptoprosopic compared to 153 (92.2%) female participants. The FI did not show a significant correlation with age, height, weight, or body mass index (BMI). However, MFL exhibited weak to moderate positive correlations with age, height, weight, and BMI. BZB also showed weak but statistically significant positive correlations with height and weight.

The hyperleptoprosopic facial type was the most common in both male and female participants, with the FI showing no significant differences between sexes. These findings enhance the anthropometric characterization of this indigenous population, providing important reference data that can be applied in forensic investigations, anthropological studies, and clinical assessments.