Use of the first rib for adult age estimation: a test of one method

The human first rib is relatively easy to identify and is often preserved, in comparison with elements such as the fourth rib and pubic symphysis. Therefore it is potentially a valuable skeletal element for estimating age in forensic and archaeological contexts. A method of adult age estimation using the first rib (Kunos et al., 1999) is tested on a sample of known age skeletons from the J.C.B. Grant Collection (n = 29, mean age = 55.7 years). The high correlation coefficient (r = 0.69) and moderate coefficient of determination (r2 = 0.47) demonstrate agreement between the known and estimated ages, suggesting that the first rib demonstates morphological changes with age. The inaccuracy and bias are high (all ages inaccuracy = 10.4 years, bias = 4.7 years) but comparable to several other age estimation methods in common use. Although the results are not as good for younger age categories (< 50 years: inaccuracy and bias rank ninth of nine age estimation methods), the inaccuracy and bias for the older age categories are relatively low (60 + years inaccuracy = 8.9 years, ranks third out of nine; bias = − 5.8 years, ranks first out of nine) compared with other age estimation methods. The first rib method is reasonably precise (93% of individuals fall within the limits of agreement of the mean difference between two trials). The first rib method is therefore a useful addition to the methods available for biological profile reconstructions from skeletal remains, especially if it is suspected that the remains represent an older individual.