The extraction of those fragments, in a laboratory in Copenhagen, was a delicate technical achievement.

The researchers worked in a cleanroom facility specifically designed to exclude modern human DNA — any contamination from the lab workers’ own cells would render the ancient signal impossible to separate from modern noise.

The extraction process used chemical reagents that selectively release DNA from the bone mineral, concentrating the ancient genetic material for sequencing.

The sequencing itself — the actual reading of the DNA sequence — was performed using next-generation sequencing technology, which reads millions of short DNA fragments simultaneously.

The resulting data was processed by bioinformatics pipelines designed to identify authentic ancient DNA sequences, filter out contamination, and assemble the fragmentary reads into a coherent picture of the genome.