Ancestral determination from foramen magnum

Ancestry estimation is a crucial part of the biological profile creation in forensic anthropology. Without proper classification of ancestry, other aspects of the biological profile, such as stature, can be affected. Several techniques are used by forensic anthropologists to determine ancestry of unidentified remains. Some anthropologists believe the cranium to be an excellent indicator of ancestry (Rhine 1990). The focus of this research was to determine the utility of the foramen magnum region on the cranial base as a positive indicator of ancestry. Previous studies have explored the effectiveness of using the cranial base’s occipital condyles for ancestry assignment of an individual. Holland (1986a) studied the Terry Collection, housed at the Smithsonian, to develop five multiple-regression equations. Using the same measurements as Holland (1986a) for the current research, four modern skeletal collections consisting principally of whites, blacks, and Hispanics were documented and measured. A total of 465 cranial bases comprised the sample. The hypothesis of this research stated correlations exist between the shape of the foramen magnum and ancestry of an individual. The null hypothesis stated ancestral groups are not visually and metrically different from each other. Localized changes on the cranial base have occurred. The Maximum Distance between Occipital Condyles increased in length and the Maximum Interior Distance between Occipital Condyles decreased in length. Five different foramen magnum shape categories were defined to classify each foramen magnum: Arrowhead, Circle, Diamond, Egg, and Oval. No correlations were found between foramen magnum shapes and positive assignment of ancestry or sex. However, the Egg shaped foramen magnum has the potential to be used as an eliminating non-metric characteristic for Hispanics; no individuals of presumed Hispanic ancestry possessed an Egg shaped foramen magnum. A Pearson’s chi-square showed a significant relationship between blacks, whites, and Hispanics, and foramen magnum shape (p = 0.05). Metric variation of the foramen magnum width among blacks, whites, and Hispanics is significant (p = 0.05). Also, variation between sexes was significant in eight of the 12 measurements (p = 0.05). Ultimately, the null hypothesis for shape variation could not be rejected, while the null hypothesis for metric variation could be accepted