Morphological variation in cervical spinous processes: potential applications in the forensic identification of race from the skeleton.

Determination of race (ancestry) is an important step in the identification of individuals in forensic cases. Race is most commonly assessed using cranial traits. Few reliable postcranial indicators are known. In this study, the frequency of bifidity of cervical spinous processes at different vertebral levels was examined in a sample of 359 Americans of African (black) and European (white) descent. The sample was selected from the Hamann-Todd collection, a large modern anatomical collection of known sex and race. Spinous processes were classified as "bifid," "partially bifid," or "nonbifid" based on previously defined criteria. Sex and race were kept entirely unknown to the classifier (S.M.D.) during data collection. Data were analyzed using Chi-square and logistic regression analysis. At C2, most individuals (91%) had bifid spinous processes. At C7, nearly all (98%) had nonbifid spinous processes. Significant differences between race/sex subgroups were found at C3-C6. At each of these levels, whites showed a higher frequency of bifidity than blacks and males a higher frequency of bifidity than females. Differences between races were greater than differences within races. Logistic regression analysis revealed C3 and C4 to be the most useful levels for identifying race. Based on these levels, 76.05% of a validation subsample was correctly classified by race (80.25% for whites, 72.09% for blacks). Pending further study, morphology of the cervical spinous processes may provide an additional method for the determination of race in skeletal forensic cases.