The water was cold by tropical standards, which slowed degradation.

It was relatively low in the organic acids that attack DNA most aggressively.

And the mineral content of the water had, in some cases, helped to stabilize the bone structure in ways that improved DNA preservation.

The teeth were the best source.

Tooth enamel and dentine are among the densest tissues in the human body, and they provide some protection for the ancient DNA trapped within the tooth structure.

Naia’s teeth were well-enough preserved that when researchers extracted material from them and subjected that material to the next-generation sequencing protocols that had by then been developed for ancient DNA analysis, they obtained a result.