Thor Heyerdahl was born in Larvik, the son of master brewer Thor Heyerdahl and his wife Alison Lyng. As a young child, Thor Heyerdahl showed a strong interest in zoology. He created a small museum in his childhood home, with a Vipera berus as the main attraction. He studied Zoology and Geography at University of Oslo. At the same time, he privately studied Polynesian culture and history, consulting what was then the world's largest private collection of books and papers on Polynesia, owned by Bjarne Kropelien, a wealthy wine merchant in Oslo. This collection was later purchased by the University of Oslo Library from Kropelien's heirs and was attached to the Kon-Tiki Museum research department. After seven terms and consultations with experts in Berlin, a project was developed and sponsored by his zoology professors, Kristine Bonnevie and Hjalmar Broch. He was to visit some isolated Pacific island groups and study how the local animals had found their way there. Just before sailing together to the Marquesas Islands in 1936, he married his first wife, Liv Coucheron-Torp (b. 1916), whom he had met shortly before enrolling at the University, and who had studied economics there. Though she is conspicuously absent from many of his papers and talks, Liv participated in nearly all of Thor's journeys, with the exception of the Kon-Tiki Expedition.The couple had two sons; Thor Jr and Bjørn. The marriage ended in divorce and in 1949 Thor Heyerdahl married Yvonne Dedekam-Simonsen. They in turn had three daughters; Annette, Marian and Helene Elisabeth. This marriage also ended in divorce, in 1969. In 1991 Thor Heyerdahl married for the third time, to Jacqueline Beer (b. 1932).

The events surrounding his stay on the Marquesas, most of the time on Fatu Hiva, were told first in his book På Jakt efter Paradiset (Hunt for Paradise) (1938), which was published in Norway but, following the outbreak of World War II, never translated and largely forgotten. Many years later, having achieved notability with other adventures and books on other subjects, Heyerdahl published a new account of this voyage under the title Fatu Hiva (London: Allen & Unwin, 1974).

In the Kon-Tiki Expedition, Heyerdahl and five fellow adventurers went to Peru, where they constructed a pae-pae raft from balsa wood and other native materials, a raft that they called the Kon-Tiki. The Kon-Tiki expedition was inspired by old reports and drawings made by the Spanish Conquistadors of Inca rafts, and by native legends and archaeological evidence suggesting contact between South America and Polynesia. After a 101 day, 4,300 mile (8,000 km) journey across the Pacific Ocean, Kon-Tiki smashed into the reef at Raroia in the Tuamotu Islands on August 7, 1947.

Kon-Tiki demonstrated that it was possible for a primitive raft to sail the Pacific with relative ease and safety, especially to the west (with the wind). The raft proved to be highly maneuverable, and fish congregated between the nine balsa logs in such numbers that ancient sailors could have possibly relied on fish for hydration in the absence of other sources of fresh water. Inspired by Kon-Tiki, other rafts have repeated the voyage. Heyerdahl's book about the expedition, Kon-Tiki, has been translated into over 50 languages. The documentary film of the expedition, itself entitled Kon-Tiki, won an Academy Award in 1951.

Anthropologists continue to believe, based on linguistic, physical, and genetic evidence, that Polynesia was settled from west to east, migration having begun from the Asian mainland. There are controversial indications, though, of some sort of South American/Polynesian contact, most notably in the fact that the South American sweet potato served as a dietary staple throughout much of Polynesia. Heyerdahl attempted to counter the linguistic argument with the analogy that, guessing the origin of African-Americans, he would prefer to believe that they came from Africa, judging from their skin colour, and not from England, judging from their speech.

Heyerdahl's theory of Polynesian origins

Heyerdahl claimed that in Incan legend there was a sun-god named Con-Tici Viracocha who was the supreme head of the mythical fair-skinned people in Peru. The original name for Viracocha was Kon-Tiki or Illa-Tiki, which means Sun-Tiki or Fire-Tiki. Kon-Tiki was high priest and sun-king of these legendary "white men" who left enormous ruins on the shores of Lake Titicaca. The legend continues with the mysterious bearded white men being attacked by a chief named Cari who came from the Coquimbo Valley. They had a battle on an island in Lake Titicaca, and the fair race was massacred. However, Kon-Tiki and his closest companions managed to escape and later arrived on the Pacific coast. The legend ends with Kon-Tiki and his companions disappearing westward out to sea.

When the Spaniards came to Peru, Heyerdahl asserted, the Incas told them that the colossal monuments that stood deserted about the landscape were erected by a race of white gods who had lived there before the Incas themselves became rulers. The Incas described these "white gods" as wise, peaceful instructors who had originally come from the north in the "morning of time" and taught the Incas' primitive forefathers architecture as well as manners and customs. They were unlike other Native Americans in that they had "white skins and long beards" and were taller than the Incas. The Incas said that the "white gods" had then left as suddenly as they had come and fled westward across the Pacific. After they had left, the Incas themselves took over power in the country.

Heyerdahl said that when the Europeans first came to the Pacific islands, they were astonished that they found some of the natives to have relatively light skins and beards. There were whole families that had pale skin, hair varying in color from reddish to blonde. In contrast, most of the Polynesians had golden-brown skin, raven-black hair, and rather flat noses. Heyerdahl claimed that when Jakob Roggeveen first discovered Easter Island in 1722, he supposedly noticed that many of the natives were white-skinned. Heyerdahl claimed that these people could count their ancestors who were "white-skinned" right back to the time of Tiki and Hotu Matua, when they first came sailing across the sea "from a mountainous land in the east which was scorched by the sun." The ethnographic evidence for these claims is outlined in Heyerdahl's book Aku Aku: The Secret of Easter Island.

Heyerdahl proposed that Tiki's neolithic people colonized the then-uninhabited Polynesian islands as far north as Hawaii, as far south as New Zealand, as far east as Easter Island, and as far west as Samoa and Tonga around 500 AD. They supposedly sailed from Peru to the Polynesian islands on pae-paes--large rafts built from balsa logs, complete with sails and each with a small cottage. They built enormous stone statues carved in the image of human beings on Pitcairn, the Marquesas, and Easter Island that resembled those in Peru. They also built huge pyramids on Tahiti and Samoa with steps like those in Peru. But all over Polynesia, Heyerdahl found indications that Tiki's peaceable race had not been able to hold the islands alone for long. He found evidence that suggested that seagoing war canoes as large as Viking ships and lashed together two and two had brought Stone Age Northwest American Indians to Polynesia around 1100 CE, and they mingled with Tiki's people. The oral history of the people of Easter Island, at least as it was documented by Heyerdahl, is completely consistent with this theory, as is the archaeological record he examined (Heyerdahl 1958). In particular, Heyerdahl obtained a radiocarbon date of 400 CE for a charcoal fire located in the pit that was held by the people of Easter Island to have been used as an "oven" by the "Long Ears," which Heyerdahl's Rapa Nui sources, reciting oral tradition, identified as a white race which had ruled the island in the past (Heyerdahl 1958).

Heyerdahl further argued in his book American Indians in the Pacific that the current inhabitants of Polynesia migrated from an Asian source, but via an alternate route. He proposes that Polynesians traveled with the wind along the North Pacific current. These migrants then arrived in British Columbia. Heyerdahl called contemporary tribes of British Columbia, such as the Tlingit and Haida, descendants of these migrants. Heyerdahl claimed that cultural and physical similarities existed between these British Columbian tribes, Polynesians, and the Old World source. Heyerdahl's claims aside, however, there is no evidence that the Tlingit, Haida or other British Columbian tribes have an affinity with Polynesians.

Heyerdahl's theory of Polynesian origins never gained acceptance by anthropologists. Physical and cultural evidence had long suggested that Polynesia was settled from west to east, migration having begun from the Asian mainland, not South America. In the late 1990s, genetic testing found that the mitochondrial DNA of the Polynesians is more similar to people from southeast Asia than to people from South America, showing that their ancestors most likely came from Asia. Easter Islanders are of Polynesian descent.

Anthropologist Robert C. Suggs included a chapter on "The Kon-Tiki Myth" in his book on Polynesia, concluding that "The Kon-Tiki theory is about as plausible as the tales of Atlantis, Mu, and 'Children of the Sun.' Like most such theories it makes exciting light reading, but as an example of scientific method it fares quite poorly."

In 1955-1956, Heyerdahl organized the Norwegian Archaeological Expedition to Rapa Nui (Easter Island). The expedition's scientific staff included Arne Skjølsvold, Carlyle Smith, Edwin Ferdon, Gonzalo Figueroa and William Mulloy. Heyerdahl and the professional archaeologists who traveled with him spent several months on Rapa Nui investigating several important archaeological sites. Highlights of the project include experiments in the carving, transport and erection of the notable moai, as well as excavations at such prominent sites as Orongo and Poike. The expedition published two large volumes of scientific reports (Reports of the Norwegian Archaeological Expedition to Easter Island and the East Pacific) and Heyerdahl later added a third (The Art of Easter Island). Heyerdahl's popular book on the subject, Aku-Aku was another international best-seller.

In "Easter Island: the Mystery Solved" (Random House, 1989), Heyerdahl offered a more detailed theory of the island's history. Based on native testimony and archeological research, he claimed the island was originally colonized by Hanau eepe ("Long Ears"), from South America, and that Polynesians Hanua momoko ("Short Ears") arrived only in the mid-16th century; they may have come independently or perhaps were imported as workers. According to Heyerdahl, something happened between Admiral Roggeveen's discovery of the island in 1722 and James Cook's visit in 1774; while Roggeveen encountered white, Indian, and Polynesian people living in relative harmony and prosperity, Cook encountered a much smaller population consisting mainly of Polynesians and living in privation.

Heyerdahl speculates there was an uprising of "Short Ears" against the ruling "Long Ears." The "Long Ears" dug a defensive moat on the eastern end of the island and filled it with kindling. During the uprising, Heyerdahl claimed, the "Long Ears" ignited their moat and retreated behind it, but the "Short Ears" found a way around it, came up from behind, and pushed all but two of the "Long Ears" into the fire.

In 1969 and 1970, Heyerdahl built two boats from papyrus and attempted to cross the Atlantic from Morocco in Africa. Based on drawings and models from ancient Egypt, the first boat, named Ra, was constructed by boat builders from Lake Chad in the Republic of Chad using papyrus reed obtained from Lake Tana in Ethiopia and launched into the Atlantic Ocean from the coast of Morocco. After a number of weeks, Ra took on water after its crew made modifications to the vessel that caused it to sag and break apart. The ship was abandoned and the following year, another similar vessel, Ra II was built using totora reed instead, by boatmen from Lake Titicaca in Bolivia and likewise set sail across the Atlantic from Morocco, this time with great success. The boat reached Barbados, thus demonstrating that mariners could have dealt with trans-Atlantic voyages by sailing with the Canary Current.

A book, The Ra Expeditions, and a film documentary were made about the voyages.

Apart from the primary aspects of the expedition, Heyerdahl deliberately selected a crew representing a great diversity in race, nationality, religion and political viewpoint in order to demonstrate that at least on their own little floating island, people could cooperate and live peacefully. Additionally, the expedition took samples of ocean pollution and presented their report to the United Nations.

Heyerdahl built yet another reed boat, Tigris, which was intended to demonstrate that trade and migration could have linked Mesopotamia with the Indus Valley Civilization in what is now modern-day Pakistan. Tigris was built in Iraq and sailed with its international crew through the Persian Gulf to Pakistan and made its way into the Red Sea. After about 5 months at sea and still remaining seaworthy, the Tigris was deliberately burnt in Djibouti, on April 3, 1978 as a protest against the wars raging on every side in the Red Sea and Horn of Africa. In Heyerdahl's open letter to Kurt Waldheim he said in part:

Today we burn our proud ship... to protest against inhuman elements in the world of 1978... Now we are forced to stop at the entrance to the Red Sea. Surrounded by military airplanes and warships from the world's most civilized and developed nations, we have been denied permission by friendly governments, for reasons of security, to land anywhere, but in the tiny, and still neutral, Republic of Djibouti. Elsewhere around us, brothers and neighbors are engaged in homicide with means made available to them by those who lead humanity on our joint road into the third millennium.

To the innocent masses in all industrialized countries, we direct our appeal. We must wake up to the insane reality of our time.... We are all irresponsible, unless we demand from the responsible decision makers that modern armaments must no longer be made available to people whose former battle axes and swords our ancestors condemned.

Our planet is bigger than the reed bundles that have carried us across the seas, and yet small enough to run the same risks unless those of us still alive open our eyes and minds to the desperate need of intelligent collaboration to save ourselves and our common civilization from what we are about to convert into a sinking ship.

In the years that followed, Heyerdahl was often outspoken on issues of international peace and the environment.The Tigris was crewed by eleven men: Thor Heyerdahl (Norway), Norman Baker (USA),Carlo Mauri (Italy), Yuri Senkevich (USSR), Germán Carrasco (Mexico),Hans Petter Bohn (Norway), Rashad Nazar Salim (Iraq), Norris Brock (USA), Toru Suzuki (Japan), Detlef Zoltzek (Germany), Asbjørn Damhus (Denmark).

Heyerdahl made several visits to Azerbaijan between 1980 and 2000. Heyerdahl has long been fascinated with the rock carvings at Gobustan (about 30 miles west of Baku), having become convinced that their artistic style closely resembles the carvings found in his native Norway. The ship designs, in particular, were regarded by Heyerdahl as similar and drawn with a simple sickle - shaped line, representing the base of the boat, with vertical lines on deck, illustrating crew or, perhaps, raised oars.

Based on this and other published documentation, Heyerdahl proposes that Azerbaijan was the site of an ancient advanced civilization. He believed natives migrated north through waterways to present-day Scandinavia using ingeniously constructed vessels made of skins that could be folded like cloth. When voyagers traveled upstream, they conveniently folded their skin boats and transported them via pack animals. Herodotus also describes such boats from this region in his works of the 5th century BCE.

On this visit to Baku, Heyerdahl lectured at the Academy of Sciences about the history of ancient Nordic Kings. He spoke of a notation made by Snorri, a 13th-century historian, which reads: "Odin (a Scandinavian god who was one of the kings) came to the North with his people from a country called Aser." Heyerdahl claimed that the geographic location of Aser matches the region of contemporary Azerbaijan-"east of the Caucasus mountains and the Black Sea".

"We are no longer talking about mythology," says Heyerdahl, "but of the realities of geography and history. Azerbaijanis should be proud of their ancient culture. It is just as rich and ancient as that of China and Mesopotamia."

Heyerdahl challenged historians and scientists to go beyond the dogmatic medieval view of history that puts Europe in the center of exploration, discovery and settlement of the rest of the world. He believed Europe arrived later in the global scheme of things, and that Azerbaijan may well be one of the very first centers of migration.

In 1995 Thor Heyerdahl wrote:

Azerbaijan and not northern Europe was the spreading center of the Caucasian people buried in northwestern China some 4,000 years ago and now discovered by Chinese archaeologists who theorize (probably wrongly) that they came from northern Europe because they were tall, blond, blue-eyed and with Caucasian features. According to modern scholars in Azerbaijan, there used to be a strong blond and fair-skinned element in the aboriginal Azeri population, as illustrated by the stone-age hunters at the Gobustan Museum. Subsequent invasions by Romans and Arabs have somewhat modified the original Azeri type.

As to the remarkably high level of culture evinced by the 4,000 year old mummies in China, no people in Northern Europe had reached a corresponding cultural level at that early time. But the merchants of Azerbaijan could have, due to their long-range trade by skin-boats with Babylonia.

We must as scientists get beyond the dogmatic medieval view of history printed by us in Europe in which we describe our own ancestors as the discoverers of the rest of the world. There were advanced civilizations with navigators and script in Asia, Africa and Middle America before mariners from Crete brought script and civilization from the Middle East to southern Europe. Before European history began, mariners from Africa had settled the Canary Island, voyagers from America had settled the West Indies, and every inhabitable island in the Indian Ocean and the Pacific had been peopled from Asia and America. Azerbaijan, and not Europe, was part of the fermenting kettle of brewing civilization with navigators that spread early trade and cultural impulses far and wide.

Heyerdahl also investigated the mounds found on the Maldive Islands in the Indian Ocean. There, he found sun-oriented foundations and courtyards, as well as statues with elongated earlobes. Hedyerdahl believed that these finds fit with his theory of a sea-faring civilization which originated in what is now Sri Lanka, colonized the Maldives, and influenced or founded the cultures of ancient South America and Easter Island. His discoveries are detailed in his book, "The Maldive Mystery."

In 1991 he studied the Pyramids of Güímar on Tenerife and declared that they were not random stone heaps but actual pyramids. He believed that he discovered their special astronomical orientation, claiming that the ancient people who built them were most likely sun worshipers due to the alignment of the pyramids. Heyerdahl advanced a theory according to which the Canaries had been bases of ancient shipping between America and the Mediterranean.

His last project was presented in the book Jakten på Odin, (The Search for Odin), in which he initiated excavations in Azov, near the Sea of Azov at the northeast of the Black Sea. He searched for the remains of a civilization to match the account of Snorri Sturluson in Ynglinga saga, where Snorri describes how a chief called Odin led a tribe, called the Æsir in a migration northwards through Saxland, to Fyn in Denmark settling in Sweden. There, according to Snorri, he so impressed the natives with his diverse skills that they started worshipping him as a god after his death (see also House of Ynglings and Mythological kings of Sweden). Heyerdahl accepted Snorri's story as literal truth. This project generated harsh criticism and accusations of pseudo-science from historians, archaeologists and linguists in Norway, who accused Heyerdahl of selective use of sources, and a basic lack of scientific methodology in his work.

The central claims in this book are based on similarities of names in Norse mythology and geographic names in the Black Sea-region, e.g. Azov and æsir, Udi and Odin, Tyr and Turkey. Philologists and historians reject these parallels as mere coincidences, and also anachronisms, for instance the city of Azov did not have that name until over 1000 years after Heyerdahl claims the æsir dwellt there. The controversy surrounding the search for Odin-project was in many ways typical of the relationship between Heyerdahl and the academic community. His theories rarely won any scientific acceptance, whereas Heyerdahl himself rejected all scientific criticism and concentrated on publishing his theories in popular books aimed at the general public.

Heyerdahl claimed that the Udi ethnic minority in Azerbaijan was the descendants of the ancestors of the Scandinavians. He travelled to Azerbaijan on a number of occasions in the final two decades of his life and visited the Kish church. Heyerdahl's Odin theory was rejected by historians, archaeologists, and linguists.

Heyerdahl was also an active figure in Green politics. He was the recipient of numerous medals and awards. He also received 11 honorary doctorates from universities in the Americas and Europe.

In subsequent years, Heyerdahl was involved with many other expeditions and archaeological projects. However, he remained best known for his boat-building, and for his emphasis on cultural diffusionism. He died, aged 87, from a brain tumor. After receiving the diagnosis he prepared for dying by refusing to eat or take medication. The Norwegian government granted Heyerdahl the honor of a state funeral in the Oslo Cathedral on April 26, 2002. His cremated remains lie in the garden of his family's home in Colla Micheri.

On the occasion of the 1994 Winter Olympics Heyerdahl was the presenter during the opening and closing ceremonies.

Ragnar Kvam, a Norwegian historian, has criticized Heyerdahl's lack of objections to the National Socialist regime. The background of this criticism is that, in February 1938, Heyerdahl, having visited the Marquesas Islands, travelled to Berlin, where he presented himself at Professor Hans Günther's office. Günther, a Nazi race researcher, was delighted to receive from Heyerdahl a skull from a native of the Marquesas Islands. After the meeting, Heyerdahl sent his mother a letter, in which he described Günther as "one of the leading men of the new Reich."

• Heyerdahl's expeditions were spectacular and caught the public imagination. Although much of his work remains unaccepted within the scientific community, Heyerdahl increased public interest in ancient history and anthropology. He also showed that long distance ocean voyages were possible with ancient designs. As such, he was a major practitioner of experimental archaeology. He introduced readers of all ages to the fields of archaeology and ethnology.

• In 1954 William Willis sailed alone from Peru to American Samoa on the small raft named "Seven Little Sisters".

• Kantuta Expeditions, a repeated expeditions of Kon-Tiki by Eduard Ingris.

• Thor Heyerdahl's grandson, Olav Heyerdahl, retraced his grandfather's Kon-Tiki voyage in 2006, as part of a six-member crew. The voyage, called the Tangaroa Expedition, was intended as a tribute to Thor Heyerdahl, as well as a means to monitor the Pacific Ocean's environment. A film about the voyage is in preparation.

Heyerdahl's numerous awards and honors include the following:

• Retzius Medal, Royal Swedish Society for Anthropology and Geography (1950)
• Mungo Park Medal, Royal Scottish Society for Geography (1951)
• Bonaparte-Wyse Gold Medal, Société de Géographie de Paris (1951)
• Commander of the Royal Norwegian Order of St Olav (1951) and with Star, (1970)
• Bush Kent Kane Gold Medal, Geographical Society of Philadelphia (1952)
• Honorary Member, Geographical Societies of Norway (1953), Peru (1953), Brazil (1954).
• El Orden por Meritos Distinguidos, Peru (1953)
• Elected Member Norwegian Academy of Sciences (1958)
• Fellow, New York Academy of Sciences (1960)
• Doctor Honoris Causa, University of Oslo, Norway (1961)
• Vega Gold Medal, Swedish Society for Anthropology and Geography (1962)
• Lomonosov Medal, Moscow State University (1962)
• Gold Medal, Royal Geographical Society, London (1964)
• Distinguished Service Award, Pacific Lutheran University, Tacoma, Washington, USA (1966)
• Grande Ufficiale Ordine Al Merito della Republica Italiana (1968)
• Knight in the Order of Saint-John of Jerusalem.
• Order of Merit, Egypt (1971)
• Grand Officer, Royal Alaouites Order, Morocco (1971)
• Kiril i Metodi Award, Geographical Society, Bulgaria (1972)
• Honorary Professor, Instituto Politécnico Nacional, Mexico (1972)
• Officer, La Orden El Sol del Peru (1975)
• International Pahlavi Environment Prize, United Nations (1978)
• Order of the Golden Ark, Netherlands (1980)
• Doctor Honoris Causa, USSR Academy of Science (1980)
• Bradford Washburn Award, Museum of Science, Boston, USA, (1982)
• Doctor Honoris Causa, University of San Martin, Lima, Peru, (1991)
• Doctor Honoris Causa, University of Havana, Cuba (1992)
• Doctor Honoris Causa, University of Kiev, Ukraine (1993)
• President's Medal, Pacific Lutheran University, Tacoma, USA (1996)
• Civitan International World Citizenship Award