How Physical and Molecular Anthropology Interplay in the Creation of Biological Profiles of Unidentified Migrants

The skeletal sex and ancestry of unidentified human crania can be inferred both from physical and from molecular features. This paper depicts and discusses the experiences of physical and molecular anthropologists on a set of commingled crania from the largest Mediterranean shipwreck disaster on 18 April 2015, in order to facilitate identification of human crania. Twenty-one disarticulated crania that were recovered from the above-mentioned shipwreck were analyzed to estimate skeletal sex and ancestry, following a physical and a molecular pipeline. The physical analyses applied morphological and metric methods that provided posterior probabilities for the crania to be classified into a sex or ancestral group. The molecular analyses were performed on petrous bones via a shotgun sequencing approach that allowed us to determine the sex of each individual and to retrieve the complete mitochondrial genome, Y chromosome single nucleotide polymorphisms, up to 597573 SNPs across the human genome from each individual. The morphometric sex analyses showed that most crania belonged to male individuals, although some estimations remained uncertain or undetermined. Inconsistent results were obtained for ancestry estimation as well, since morphological methods classified the crania mostly as European/White, in contrast to the most numerous African forms determined by craniometric analyses. This quite agreed with molecular analyses that identified only African males. Overall, undetermined and contrasting results were obtained between disciplines, preventing the creation of reliable and sound biological profiles that could provide guidance on the sex and ancestral group of the victims. Therefore, the times may not be mature for a merger of physical and molecular anthropology. However, future investigations of this research avenue would pave the way to the possible development of novel tools, methods, and wider reference databases that could address the limitations of both disciplines.