A milk tooth, lying in the sediment of a Pleistocene archaeological site, is not obviously more significant than the hundreds of other biological materials recovered from the same layers.

What made them significant — what transformed two small teeth into the keys to a lost population — was the DNA they contained and the technology that could read it.

That technology did not exist when the Yana site was first excavated.

The site’s significance for ancient DNA research was not anticipated when the major artifact finds — the rhino horn foreshaft, the ivory foreshafts, the needles, the ornament — were first being recovered and analyzed.

This is a reminder of the degree to which archaeological interpretation is always provisional.