Solid biological samples from millennia past might not be as common as stone tools or other archaeological evidence, but there are plenty of other candidates for sequencing, Willerslev noted. The limiting factor will likely not be the number of specimens or even their potential contamination, Rasmussen said: "What will limit us is fragment size." In order to come up with enough genomic material to sequence and check as many as 20 times over, researchers need a large enough biological sample to study.
Such detailed insight can also provide new information about genetic mutations—from skin tone to genetic disease risk—across the millennia. Establishing that sequencing the genome of ancient individuals is possible "opens up the possibility to go back in time and see" when genetic diseases became prevalent in different populations, Willerslev said. And for more modern populations that met recent ends, such as many Native American groups and native Tasmanians, genetic sequencing can answer some previously unknowable information about those groups.