Sampling Skeletal Remains for Ancient DNA (aDNA): A Measure of Success

More than 2,000 samples of human osseous and dental materials drawn from forensic archaeological casework of the Joint POW/MIA Accounting Command Central Identification Laboratory (CIL) were submitted for mitochondrial DNA testing. Most cases represent unidentified remains of U.S. service personnel from World War II, the Korean War, and the Vietnam War. Ancient DNA sampling technique is discussed in the context of an overall strategy of minimizing the risk of contamination with exogenous DNA. Results achieved through implementation of this strategy are reviewed with the intent of providing historical archaeologists with data to assist them in deciding if human remains should be samples for DNA analyses and, if so, how to maximize the chances of an interpretable test outcome. Sample mass proved an important determinant of probability of successful DNA testing. Skeletal element sampled was also a determinant of success rate, independent of sample mass. Femora, tibiae, mandibles, and first metatarsals were excellent sample sources. Cranial samples had low rates of DNA recovery. Climate of deposition and recovery had a minor effect on success rate with temperate recoveries outperforming tropical recoveries in DNA testing success rates. Contrary to initial expectations, older samples performed better than younger samples. This inverse age effect is attributed to conflict-specific taphonomic processes. The lack of any detectable effect over the past 60 years suggests that as long as bones are well preserved and optimal elements well represented, aDNA testing will be relatively unproblematic over time spans of hundreds of years, certainly encompassing the entire time span considered by historical archaeologists.