A comparison of proteomic, genomic, and osteological methods of archaeological sex estimation.

Sex estimation of skeletons is fundamental to many archaeological studies. Currently, three approaches are available to estimate sex-osteology, genomics, or proteomics, but little is known about the relative reliability of these methods in applied settings. We present matching osteological, shotgun-genomic, and proteomic data to estimate the sex of 55 individuals, each with an independent radiocarbon date between 2,440 and 100 cal BP, from two ancestral Ohlone sites in Central California. Sex estimation was possible in 100% of this burial sample using proteomics, in 91% using genomics, and in 51% using osteology. Agreement between the methods was high, however conflicts did occur. Genomic sex estimates were 100% consistent with proteomic and osteological estimates when DNA reads were above 100,000 total sequences. However, more than half the samples had DNA read numbers below this threshold, producing high rates of conflict with osteological and proteomic data where nine out of twenty conditional DNA sex estimates conflicted with proteomics. While the DNA signal decreased by an order of magnitude in the older burial samples, there was no decrease in proteomic signal. We conclude that proteomics provides an important complement to osteological and shotgun-genomic sex estimation.

Paleoepidemiological patterns of interpersonal aggression in a prehistoric central California population from CA-ALA-329.

Interpersonal aggression is assessed paleoepidemiologically in a large skeletal population from the CA-ALA-329 site located on the southeastern side of San Francisco Bay, California. This comprehensive analysis included all currently recognized skeletal criteria, including craniofacial fracture, projectile injury, forearm fracture, and perimortem bone modification. Craniofacial injury is moderately common, showing an adult prevalence of 9.0% with facial lesions accounting for >50% of involvement. Clinical studies suggest that such separate evaluation of facial involvement provides a useful perspective for understanding patterns of interpersonal aggression. In this group male facial involvement is significantly greater than in females, paralleling the pattern found widely in contemporary populations as well as in African apes. When compared to other North American skeletal samples the prevalence of adult cranial vault injury (3.3%) and especially projectile injury (4.4%) are quite high. However, well documented populations from southern California show markedly higher prevalence for both types of skeletal markers of aggression. Forearm fracture is also assessed using a rigorous radiographic methodology and results suggest that these injuries are not reliable indicators of interpersonal aggression. Lastly, perimortem bone modification was not observed in this population, although it has been recorded from other (older) sites nearby. This study provides an evaluation of multiple skeletal markers of interpersonal aggression in the largest sample from a single site yet reported in North America and, joined with consideration of cultural context, helps further illuminate both geographic and temporal patterns of interpersonal aggression in California.