Commingling refers to the situation where more than one individual is represented and have become mixed together; the sorting of individuals in a commingled assemblage is critical in post conflict situations such as mass graves. There are strong correlations among the sizes of bones. If someone has a large humerus, you can expect that they will have a large femur. Osteometric sorting removes the subjective judgment and relies solely on statistics to make the decision. Osteometric sorting uses measurements to compare size differences between two skeletal elements and the same elements in a reference population. Segregation decisions are made by testing the null hypothesis that the two specimens of interest are of a similar size and shape to have originated from a single individual. In this study, the Piggot ossuary (31CR14) is employed to represent a large-scale commingling.

The Piggot ossuary site (31CR14) was used to represent a mass disaster, large scale commingling. The JPAC-CIL database was utilized as the reference sample (n=579). Visual pair matching was performed on left and right sides. Measurements were taken according to Buikstra and Ubelaker (1994) and Byrd and Adams (2003). Three models were used for osteometric sorting:

Model 1: Compares left and right sides D = Σ(ai –bi) H0 is tested by comparing the value of D against zero and using the reference data standard deviation of D. The deviation from zero, divided by the reference data standard deviation is evaluated against the two-tailed t-distribution to obtain a p-value α=0.10

Model 2: Compares bone articulations D = ci –dj H0 is evaluated by comparing the value of D from the case specimens, to the mean value of D, calculated from the reference data. The deviation of D from the reference data mean, divided by the reference data standard deviation, is evaluated against the two-tailed t-distribution to obtain a p-value α=0.10

Model 3: Compares different bone sizes Natural logarithm is taken for the sum of all available bone measurements and used in the regression models

𝒕 = 𝒚^ − 𝒚𝒊 /[ 𝑺.𝑬 [𝟏 + 𝟏𝑵

+ (𝒙𝒊 − 𝒙)𝟐/(𝑵 ∗ 𝑺𝒙𝟐)]]

A two-tailed t-distribution is calculated in Microsoft Excel α=0.10

Model 1

The purpose of this study was to illustrate the practicality of utilizing gross and osteometric sorting techniques as a first approach in the sorting of commingled human remains.

Model 2

1078.3-1081.2 415.3-1082.2 D=3.8

t=0.989 p=0.324

D=7.9 t=2.055 p=0.041

643.1-637.2 1117.2-637.2

D=7.6 t=1.229 p=0.220

D=3.9 t=3.527 p=0.00

Model 3

t=0.517 p=0.606

t=4.791 p=0.00

1115.3-657.1 1115.3-1801.1

Kristen R. Chew, B.A.

Results for model 1 show two comparisons between left and right humeri. Comparison a was initially pair matched via taphonomy and epiphyseal fusion lines. This comparison likely represents a pair of right and left humeri that may have originated from a single individual (p=0.324). The two bones of model 1, comparison b were not paired, suggesting that the two bones likely did not originate from a single individual (p=0.041). The photo illustrates the size difference. Results for model 2 show comparisons between a left femur when compared to two different left innominates. The max head diameter of the femur was compared to the size of the acetabulum. The two bones in comparison a were not significantly different (p=0.220), suggesting that they could have originated from a single individual. The two bones of model 2, comparison b were significantly different (p=0.00), suggesting that these bones were too different in size and could not have originated from a single individual. Model 3 compared a right femur to a left humerus. The two bones of comparison a were not significantly different in size and/or shape (p=0.606), suggesting that these two bones could have originated from a single individual. The two bones of model 3, comparison b were significantly different in size and/or shape (p=0.00), suggesting that it is not possible that these two bones could have originated from a single individual.

Humerus=0.199+0.921(Femur) N R p Std. Error

294 0.93 0.00 0.025

Anthropological techniques for the sorting of commingled human remains are an important first step in the sorting of commingled human remains. The gross and metric sorting procedures can be beneficial in cases of large scale commingling, particularly in situations when there are time and monetary constraints. The use of gross and osteometric techniques could provide a first step in segregating commingled individuals, which could eliminate the need to perform DNA profile testing on each individual bone.

Byrd, J.E. 2008. Models and Methods for Osteometric Sorting. In: Recovery, Analysis, and Identification of Commingled Human Remains, Karch, Steven B. and Adams, Bradley J, eds. Humana Press, Totowa, NJ Byrd, J.E., Adams, B.J. 2003. Osteometric sorting of commingled human remains. J Forensic Sci 48(4):717-724.Adams BJ, Byrd JE. 2002. Interobserver variation of selected postcranial skeletal measurements. J Forensic Sci 47(6):1193-1202. Buikstra JE, Ubelaker DH. 1994. Standards for data collection from human skeletal remains.Garrett, Amy. 2012. Osteological Analysis of a Late Woodland North Carolina Ossuary: The Piggot Site (31CR14), Carteret County, North Carolina. Master’s thesis, North Carolina State University, Department of Anthropology. Adams BJ, Byrd JE. 2002. Interobserver variation of selected postcranial skeletal measurements. J Forensic Sci 47(6):1193-1202. Garrett A. 2012. Osteological analysis of a late woodland north carolina ossuary: The piggot site (31CR14), carteret county, north carolina. Master's, North Carolina State University, Department of Anthropology.

a b

a b

a b