The Tollund Man is by no means the only bog person to have been uncovered in recent decades. About a thousand others have been found in Ireland, England, Denmark and the Low Countries.

The result is that a bog body may be found centuries, or even thousands of years, after it fell into the peat; the oldest known, Koelbjerg Man from Denmark, died in around 8,000 B.C.

When the team of archaeologists from Aarhus University began finding human bones in Alken Enge bog in eastern Denmark three years ago, they weren’t sure what to think—but they knew they wanted ...