After a variety of labouring jobs, he eventually made his way to England and joined the Free Norwegian Army, where he was trained as a saboteur and wireless operator, although several aborted missions meant that he never saw action.
After the success of the Kon-Tiki expedition, which in 1951 brought him the Oscar for Best Documentary Film, Heyerdahl set up a museum to house the vessel in Oslo and then concentrated on the archaeological search for further proof of his theories.
The crew supplemented their US Army issue rations with freshly caught shark.
Although Heyerdahl had undertaken the voyage purely for scientific reasons, the exploit caught the world's imagination, and he found himself a much feted figure.
In later years, he came rather to resent the celebrity the Kon-Tiki had brought him, arguing that it had pigeon-holed him as a daredevil explorer rather than as a man of science, and that this had made it harder for him to persuade his fellow academics of the veracity of his theories.
His father ran a mineral water plant and a brewery while his mother, a keen Darwinist, ran the town museum.
He was schooled locally, and from an early age roamed the woods that ran down to the edge of the town and later made expeditions into the mountains by sledge with his pet husky.
On April 28 1947, the Kon-Tiki pushed off from the Peruvian port of Callao.
For 101 days it drifted across the Pacific, pushed towards Polynesia - as Heyerdahl had predicted - by warm currents and the south-east trade wind.
The craft was named Kon-Tiki, after the mythical Polynesian hero Tiki, who was said in oral tradition to have led the ancestors of the islanders there from the East.
Heyerdahl had first heard the legend in the mid-1930s, while he was living in the Pacific on the Marquesas Islands, and had connected this Polynesian Aeneas with the Inca tale of Con-Tici, the fair-skinned king said to have fled from Peru across the ocean following the massacre of his race at Lake Titicaca some 500 years before the birth of Christ.
A Question of Origins 60 minute documentary by Eternal Productions has been translated into Spanish, Italian, Portuguese, Russian, Polish, Serbian, and Slovakian.
Against all prevailing expert opinion, Heyerdahl's researches had convinced him that ethnological traits common to Polynesia and South America were the result of pre-historic transoceanic migration by Peruvian Indians, perhaps around 500 BC.
After accidentally falling into a river, Heyerdahl discovered that he could swim: "I realised that the ocean buoyed me up instead of sucking me down," he wrote later.