Association Between Digit Ratio (2D:4D) and Aggressiveness in a Community Population of Sekampung Udik, East Lampung, Indonesia

Biology Study Program, Institut Teknologi Sumatera, South Lampung, 35365, Indonesia

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Abstract

The digit ratio (2D:4D), defined as the relative length of the index (2D) to the ring finger (4D), reflects prenatal exposure to testosterone and estrogen. Higher prenatal testosterone exposure is associated with increased aggressiveness. Objective: This cross-sectional, community-based study aimed to examine the effect of the 2D:4D ratio on aggressiveness among communities in Sekampung Udik, East Lampung. Methods: A total of 300 respondents (male and female, aged 15-59 years) from three villages, Sidorejo, Pugung Raharjo, and Sindang Anom, were surveyed between January and March 2025. The 2D:4D ratio was measured using a digital caliper, whereas aggressiveness was assessed using the Buss and Perry Aggression Questionnaire. Data were analyzed using Linear Models (LM) in R version 4.4.2. Results: Results indicated that a lower left-hand 2D:4D ratio was significantly associated with higher levels of verbal aggressiveness (p = 0.0184), anger (p = 0.0038), and hostility (p = 0.0155). Demographic factors, including female sex, number of siblings, and domicile in Sidorejo Village, also significantly influenced aggressiveness. Conclusion: These findings suggest that both biological markers and sociodemographic factors contribute to the individual differences in aggressiveness. This study provides critical evidence for integrating biological and sociological perspectives in the study of aggressive human behavior.