Samples were taken from the dentine — the interior layer of the tooth beneath the enamel, where the cellular material that might contain DNA is concentrated.

The sampling was done in a clean laboratory environment specifically designed to minimize contamination from modern DNA, because the introduction of even a tiny amount of modern human DNA into a sample can obscure or overwhelm the ancient signal.

The extracted material was processed using chemical methods designed to liberate the nucleic acids from the mineral matrix of the dentine and to remove the substances that would inhibit subsequent analytical steps.

The resulting solution was treated to build sequencing libraries: short double-stranded DNA molecules with specific sequences added at their ends that allow them to bind to the sequencing apparatus.