Humans first reached the Society Islands, in the center of the Polynesian Triangle, perhaps around 1,000 AD. Then in the span of just a couple hundred years, they took canoes across vast tracts of open ocean to find specks of inhabitable rock as far-flung as Hawaii, New Zealand, and Easter Island. How Polynesians navigated these waters in the 11th century is a subject of considerable fascination. But even more basically, archaeologists are not sure exactly when the islands were settled and in what order. That’s where the tartar comes in.