Infracranial Epigenetic Variation and the Identification of Unknown Human Skeletal Remains

Abstract

After a potential match pool has been narrowed using the biological profile, forensic anthropologists often rely on the presence of qualitative skeletal traits for distinguishing between individuals via antemortem–postmortem comparison. This study establishes the epigenetic etiology of several such traits and examines the contribution of the following traits to forensic identification: suprascapular notch, suprascapular foramen, manubrial cleft, manubrial aperture, sternal cleft, sternal aperture, xiphoidal aperture, double-ended xiphoid process, triple-ended xiphoid process, bifid rib, butterfly vertebra, spina bifida occulta, missing transverse process of the first lumbar vertebra (L1), spondylolysis, and sacralization of the fifth lumbar vertebra (L5).

Trait frequencies were calculated in totality and according to sex, age, and side occurrence. A sample of 429 (n = 429) individuals were examined from the Bass Donated Skeletal Collection, University of Athens Human Reference Collection, Institute of Forensic Medicine at the University of Zurich, and the New Mexico Decedent Image Database.

All traits were determined to be rare (i.e., <10% frequency), except for the suprascapular notch, double-ended xiphoid, and xiphoidal foramen; these traits should not be used for identification purposes. Manubrial aperture, sternal cleft, butterfly vertebrae, and missing transverse processes have the highest utility for identification.

Only spondylolysis demonstrated a statistically significant difference between the sexes. Butterfly vertebrae and sacralization of L5 demonstrated a moderate relationship with age. No side or intertrait associations were observed. Consideration of these parameters will allow one to refine the biological profile and provide more accurate conclusions to be drawn regarding trait frequencies in a given population.