The conditions of the site — open Arctic terrain, exposed to the elements for over 140 years before scientific excavation — meant that the skeletal remains were dispersed and fragmented. Animal activity, freeze-thaw cycles, and the passage of time had moved and altered bones from their original positions. Reconstructing the site’s history required the kind of careful spatial and taphonomic analysis that archaeological excavations of historic sites typically demand, combined with the specific knowledge of human bone modification patterns that allowed researchers to distinguish cut marks made by human tools from other marks made by animals or by natural processes.
Fitzjames’s mandible — his lower jawbone — was among the specimens recovered from NgLj-2. It bore cut marks that multiple researchers have assessed as consistent with defleshing. The mandible contained a preserved molar, and that molar preserved DNA.
The specific DNA extraction was performed by Stephen Fratpietro at the Paleo-DNA Laboratory at Lakehead University in Thunder Bay, Ontario. The Paleo-DNA lab has been involved in DNA extractions from historical remains in multiple high-profile cases. The extraction of usable DNA from a tooth that had been in the Arctic environment for approximately 175 years, then in archaeological storage for some years after that, is a technically demanding process that depends on the specific preservation conditions the sample experienced.
Teeth are among the best sources of preserved ancient DNA available to researchers. The structure of a tooth — with its dense outer enamel protecting the pulp cavity and root canal interior — creates a physical barrier against the environmental intrusion of water, bacteria, and chemical agents that degrade DNA. The cold Arctic environment that preserved the NgLj-2 remains also slowed the chemical processes of DNA degradation that operate more rapidly in warmer environments. These factors together explain why a 175-year-old tooth could yield genetic material sufficient for a Y-chromosome profile.