Sex and age at death estimation from the sternal end of the fourth rib. Does Iscan's method really work?

The fourth rib has been used commonly in order to estimate age at death and even sex in skeletal remains but many often, Iscan's estimates do not adjust to the real age of the individual. Population specific references for sex and age-at-death estimation from the sternal end of the fourth rib are presented for a contemporary Mexican sample. A total of 504 ribs with known sex and age from a morgue sample were studied (444 males, 60 females, 17 to 92 years old). The height and breadth of the sternal end of the rib were sexually dimorphic (p = .000), and allowed a correct sex assignment in 73.3% to 84% of the cases from univariate and multivariate discriminant functions. With regard to age-at-death estimation, the morphological changes summarized by the phases of the sternal end of the fourth rib are correlated with known age in this sample (Spearman's Rho, p = .000). However, the original age intervals tend to underestimate age at death and inaccuracy increases with phase scored in males. Descriptive statistics for rib phase are provided for males and females, and new age-at-death estimates based on transition analysis and Bayesian statistics are provided for the male sample. The test of universally applied methods and the development of population specific references is an important task for forensic anthropology around the world.