For the past eight years I’ve been living with 72 people. These 28 men, 25 women, 12 girls, and seven boys are long dead—they were Africans sold into captivity and shipped to America in the mid-1700s. It’s generally accepted that a factual account of their experience—like almost all Africans enslaved in America—is beyond recovery. Even Roots blended fact and fiction into something its author referred to as “faction.”

But thanks to laborious archival research and the linking of two rare and …