Ancient DNA work is conducted in cleanrooms designed to minimize airborne particles, using equipment and surfaces that have been thoroughly decontaminated.

The researchers themselves must take precautions including wearing protective gear to prevent their own DNA from entering the sample.

The resulting raw material — a mixture of short, degraded DNA fragments from the ancient individual and from the various organisms that colonized the remains over time — is then sequenced and subjected to bioinformatic analysis.

Computational methods distinguish authentic ancient human DNA from contamination by looking for the specific chemical damage patterns that accumulate in DNA over long periods: particular changes to the nucleotide bases that characterize genuine ancient sequences rather than modern contamination.

Authenticating ancient DNA is not simple, and the field has developed increasingly sophisticated methods for doing so.