Intercostal variation at the sternal end of the rib

The human rib has proven to be an important site for the assessment of age at death in the adult skeleton. The rib phase method, featuring race and sex specific standards developed by two of the authors (Işcan and Loth), is proving successful in paleodemography and forensic anthropology. However, as the authors pointed out in earlier publications, it is not always possible to isolate the fourth rib upon which the standards are based. This can be a factor because although a certain degree of intercostal variation does exist, its extent has not been quantified in a modern forensic population. Therefore the purpose of this paper is to determine if standards from the fourth rib can be used for adjacent ribs 3 and 5. Ribs 3, 4, and 5 were collected at autopsy from recent medical examiner's cases of known age, sex and race. The sample consists of 135 white males and females of age range 3-99 years. Each rib was assigned to an age phase using the established standards. The results of this analysis indicated that > 79% of cases, all three ribs fell into the same phase, and intercostal differences were within one phase for 98% of the sample. It may thus be concluded that age can also be assessed from these adjacent ribs using the present standards.