Physical anthropologists could measure skulls and long bones, reconstruct diet from isotopes, estimate age and sex from biological markers.

But the genetic identity of ancient individuals — what haplogroups they carried, what their relationships were to other populations, whether they were related to the people buried nearby — was inaccessible.

That changed with the development of ancient DNA methods beginning in the 1980s and accelerating rapidly through the 1990s and 2000s.

The techniques for extracting genetic material from ancient bones and teeth, purifying it from the environmental contamination that accumulates over thousands of years, and sequencing the surviving fragments have improved so dramatically that genomes from individuals who died tens of thousands of years ago can now be read with high accuracy.

For North America specifically, the ancient DNA revolution has produced a series of landmark studies.