The specific dates reported in the paper were expressed in radiocarbon years before present, and the conversion to calibrated calendar years requires application of calibration curves that account for the known variations in atmospheric radiocarbon concentration over time.

The calibrated range placed the specimens roughly 1,000 or more radiocarbon years before the conventional Clovis horizon.

The combination — human mitochondrial DNA, directly dated to before Clovis — was, as the paper’s authors understood, a remarkable result.

It placed people in the Oregon Great Basin at a time when, according to the Clovis-first model that had dominated North American archaeology for decades, humans were not yet supposed to be there.

The paper was careful in its framing.