Born October 6, 1914, Larvik, Norway

Scientist and adventurer Thor Heyerdahl has spent much of his life trying to understand the history of people before they left written records. One question he has pondered is why certain native inhabitants of the islands of the Pacific, specifically the Polynesians, speak a single, separate language and differ so greatly in appearance from their neighbors in Micronesia and Melanesia. Did the Polynesians’ ancestors reach the Pacific by a different migratory route? Did they arrive not from the Asian mainland—as was traditionally thought—but by way of a long western journey across the ocean?

Heyerdahl has also tried to find a reason for the many shared cultural practices and beliefs of the great Indian civilizations of the Americas (such as the Aztec, Maya, and Inca) and the ancient peoples of the Middle East (such as the Egyptians). The...