The genome gives us ancestry. Ancestry is not identity. This is true for living people and it is true for people who died ninety thousand years ago.
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## The Technology That Made It Possible
The Denisova 11 finding represents the culmination of a methodological revolution in the study of human prehistory. Understanding that revolution—where it came from and why it was so transformative—helps explain both the significance of the finding and its limits.
Ancient DNA research began in the 1980s, when Svante Pääbo, then a graduate student in Sweden, managed to extract and sequence small amounts of DNA from the desiccated muscle tissue of a four-thousand-year-old Egyptian mummy. The result was published in Nature in 1985, when Pääbo was 29 years old, and it announced the possibility of reading the genomes of long-dead individuals.
The early years of the field were marked by false starts and retractions. DNA from ancient samples is rare, damaged, and contaminated; the polymerase chain reaction (PCR) method used to amplify ancient DNA samples was prone to amplifying contaminant DNA rather than the ancient material itself. High-profile claims—ancient DNA from dinosaur bones, from amber-preserved insects—were eventually shown to be the result of contamination. The field developed strict protocols for identifying authentic ancient DNA, including the presence of characteristic chemical damage patterns (cytosine deamination, which converts C to T in predictable ways) and the short fragment lengths expected from genuinely ancient material.
The transformation came in the late 2000s and early 2010s with the development of next-generation sequencing—a suite of technologies that could read millions of short DNA fragments simultaneously, rather than one fragment at a time as Sanger sequencing did. This change made it practical to sequence ancient genomes at meaningful coverage even when the proportion of ancient DNA in a sample was very low. Where earlier methods would have been overwhelmed by contaminant DNA, next-generation sequencing could read everything present and then use bioinformatic methods to identify and retain only the sequences that showed the chemical damage patterns of genuine ancient DNA.