First, DNA was extracted from the petrous bone powder under strict contamination-control conditions — ancient DNA labs are among the cleanest environments in science, because modern human DNA is everywhere (on researchers’ skin, in their breath, in the laboratory air) and a single modern human cell can overwhelm the signal from ancient DNA.

The extraction was performed in a dedicated clean room where air circulation, surface sterilization, and protective equipment are maintained to standards beyond those of ordinary biological laboratories.

The extracted DNA was then processed to prepare it for sequencing.

Ancient DNA fragments are typically very short — most fragments preserved from tens of thousands of years ago are fewer than 100 base pairs long, compared to the hundreds to thousands of base pairs that modern DNA sequencing handles routinely.

The short fragments require different library preparation protocols than modern DNA.