The technical challenge of accurately dating Kwäday Dän Ts’ìnchi’s remains is worth exploring in more detail, because it illustrates a broader problem in the dating of ancient individuals with coastal or maritime lifestyles — a problem that has affected the interpretation of radiocarbon dates from many ancient Americans with diets that included marine foods.

Radiocarbon dating depends on a fundamental assumption: that the living organism incorporated carbon from the atmosphere at the atmospheric ratio of carbon-14 to carbon-12.

When the organism dies, it stops incorporating new carbon, and the carbon-14 that is already present begins to decay at a known rate.

By measuring how much carbon-14 remains relative to carbon-12, the laboratory can calculate the age.

The problem with marine organisms — fish, shellfish, marine mammals, and the people who eat them in significant quantities — is that the ocean contains dissolved carbon that is substantially older than the carbon currently in the atmosphere.