Age estimation from the sternal end of left fourth rib in the Nepalese population

Background Forensic anthropological examinations help in identification of unidentified human remains. This study aims to establish population-specific standards for age estimation from the sternal ends of left fourth ribs in the Nepalese population. A quantitative, observational study was conducted on 387 Nepalese deceased (106 females, 281 males) between November 2021 and March 2023. Left fourth ribs were collected, macerated and examined for the study. The variables examined included pit depth, pit shape, rim and wall configurations and rib phase. Results Pit depth significantly predicted age, beta = 0.642, t(385) = 16.42, p < 0.001. Pit depth also explained a significant proportion of variance in age, R-2 = 0.41, F(1, 385) = 269.54, p < 0.001. The age estimates from pit depth stage were 7-36 (stage 0), 7-49 (stage 1), 16-51 (stage 2), 10-58 (stage 3), 22-70 (stage 4) and 32-81 (stage 5). Age estimates for pit shape were 17-20 (stage 0), 13-48 (stage 2), 15-55 (stage 3), 24-68 (stage 4) and 39-82 (stage 5). Age estimates for rim and wall configurations were 17-20 (stage 0), 13-47 (stage 2), 17-53 (stage 3), 24-68 (stage 4) and 40-82 (stage 5). Similarly, age estimates for rib phase were 17-20 (phase 0), 18-20 (phase 1), 13-46 (phase 2), 18-50 (phase 3), 23-60 (phase 4), 32-71 (phase 5), 50-76 (phase 6), 44-81 (phase 7) and 62-85 (phase 8). The study also examined the use of transitional analysis to develop posterior probability distributions for estimation of age using rib phases. Conclusion This study found significant differences in the age estimates from previous studies and shows the importance of developing population-specific models for use in forensic anthropology.