A minimally destructive protocol for DNA extraction from ancient teeth.

Ancient DNA sampling methods-although optimized for efficient DNA extraction-are destructive, relying on drilling or cutting and powdering (parts of) bones and teeth. As the field of ancient DNA has grown, so have concerns about the impact of destructive sampling of the skeletal remains from which ancient DNA is obtained. Due to a particularly high concentration of endogenous DNA, the cementum of tooth roots is often targeted for ancient DNA sampling, but destructive sampling methods of the cementum often result in the loss of at least one entire root. Here, we present a minimally destructive method for extracting ancient DNA from dental cementum present on the surface of tooth roots. This method does not require destructive drilling or grinding, and, following extraction, the tooth remains safe to handle and suitable for most morphological studies, as well as other biochemical studies, such as radiocarbon dating. We extracted and sequenced ancient DNA from 30 teeth (and nine corresponding petrous bones) using this minimally destructive extraction method in addition to a typical tooth sampling method. We find that the minimally destructive method can provide ancient DNA that is of comparable quality to extracts produced from teeth that have undergone destructive sampling processes. Further, we find that a rigorous cleaning of the tooth surface combining diluted bleach and UV light irradiation seems sufficient to minimize external contaminants usually removed through the physical removal of a superficial layer when sampling through regular powdering methods.

Dietary 14C reservoir effects and the chronology of prehistoric burials at Sakhtysh, central European Russia.

We present a robust radiocarbon (14C) chronology for burials at Sakhtysh, in European Russia, where nearly 180 inhumations of Lyalovo and Volosovo pottery-using hunter-gatherer-fishers represent the largest known populations of both groups. Past dating attempts were restricted by poor understanding of dietary 14C reservoir effects (DREs). We developed a DRE correction approach that uses multiple linear regression of differences in 14C, δ13C, and δ15N between bones and teeth of the same individuals to predict DREs of up to approximately 900 years. Our chronological model dates Lyalovo burials to the early fifth millennium BCE, and Volosovo burials to the mid-fourth to early third millennium. It reveals a change in the subsistence economy at approximately 3300 BCE, coinciding with a reorientation of trade networks, and dates the final burial to the early Fatyanovo period, the regional expression of the Yamnaya/Corded Ware expansion. Our approach is applicable when freshwater 14C reservoir effects are poorly constrained and grave goods cannot be dated directly.