In the summer of 1996, two college students in Kennewick, Washington, stumbled on a human skull while wading in the shallows along the Columbia River. They called the police. The police brought in the Benton County coroner, Floyd Johnson, who was puzzled by the skull, and he in turn contacted James Chatters, a local archaeologist. Chatters and the coroner returned to the site and, in the dying light of evening, plucked almost an entire skeleton from the mud and sand. They carried the bones back to Chatters’ lab and spread them out on a table.

The skull, while clearly old, did not look Native American. At first glance, Chatters thought it might belong to an early pioneer or trapper. But the teeth were cavity-free (signaling a diet low in sugar and starch) and worn down to the roots—a combination characteristic of prehistoric teeth. Chatters then noted something embedded in the hipbone. It proved to be a stone spearpoint, which seemed to clinch that the remains were prehistoric. He sent a bone sample off for carbon dating. The results: It was more than 9,000 years old.

Thus began the saga of Kennewick Man, one of the oldest skeletons ever found in the Americas and an object of deep fascination from the moment it was discovered. It is among the most contested set of remains on the continents as well. Now, though, after two decades, the dappled, pale brown bones are at last about to come into sharp focus...