Aku-Aku: The Secret of Easter Island

Overview

Thor Heyerdahl’s 1958 bestseller recounts his 1955, 56 expedition to Rapa Nui (Easter Island), blending travel narrative, detective story, and field report. The book sets out to understand how the island’s famous moai were quarried, moved, and raised, and to probe the island’s oral traditions, ritual life, and secret places. It extends Heyerdahl’s wider preoccupation with ancient seafaring and cultural contacts, while painting a vivid portrait of an isolated community on the cusp of change.

Expedition and discoveries

Arriving with an international team, Heyerdahl secured cooperation from Chilean authorities and Rapa Nui families to survey ahu platforms and the moai quarries at Rano Raraku. Excavations revealed that many statues were buried to their torsos, with full bodies hidden beneath wind-blown sediments. The team documented tool marks, unfinished figures, and the kneeling statue later known as Tukuturi, evidence of varied sculptural practices over centuries.

Practical experiments were central to the narrative. With islanders’ help, the team raised a fallen statue at Anakena using stone ramps, levers, and ropes, demonstrating plausible prehistoric methods without modern machinery. They also tested transport techniques, arguing that timber, sledges, and coordinated labor could account for moving multi-ton figures despite the island’s eventual deforestation.

Rapa Nui culture and the “aku-aku”

Beyond stones and measurements, the book dwells on the island’s invisible landscape of taboos and guardians. “Aku-aku” are described as protective spirits tied to families and their hidden caves. Through relationships built on trust and sworn secrecy, Heyerdahl and companions were led into lava tubes where heirlooms, carved wooden figures, ceremonial paddles, and other treasures, had been guarded for generations. These episodes supply the book’s title and its sense of intimate revelation.

The expedition also explored Orongo village on the rim of Rano Kau, rich in petroglyphs of the birdman. Heyerdahl recounts the tangata manu ritual, in which champions competed to retrieve the first egg from the offshore islet of Motu Nui, marking a religious shift after the era of statue-building. Oral traditions of clan rivalries and the collapse of the moai cult frame the island’s long history of social change, including the toppling of statues and the move toward subterranean refuges and secret shrines.

Theories and interpretations

Heyerdahl weaves field observations into a broader, controversial hypothesis: that Rapa Nui shows traces of early South American contact, possibly even an initial settlement from the east. He points to the sweet potato’s antiquity in Polynesia, reed traditions reminiscent of the Andes, and perceived stylistic echoes in stonework. Legends of two peoples, often rendered as “long-ears” and “short-ears”, are linked to a dramatic battle and burn layer, which he sought to test through excavation on the Poike peninsula.

While the book marshals experiments, stratigraphy, and lore to support possibilities of American-Polynesian contact, it also presents substantial evidence of Polynesian lifeways, navigation, and social organization. The resulting picture is a synthesis shaped by adventure and inference, inviting readers to consider multiple streams of influence in the island’s past.

Style and legacy

Written in a lively, first-person voice, the narrative balances scientific curiosity with anecdotes, portraits of collaborators, and moments of humor and tension. Photographs and drawings underscore the immediacy of the discoveries and the scale of the monuments. The book’s popularity helped reawaken global interest in Rapa Nui, encouraged restorations, and brought attention to the islanders’ heritage and agency.

Subsequent research has challenged key aspects of Heyerdahl’s diffusionist theories, favoring a primarily west-to-east Polynesian settlement with limited, if any, early American input. Yet the expedition’s documentation of sites, experiments with statue raising, and empathetic accounts of Rapa Nui culture remain influential. The enduring appeal lies in the mix of empirical spadework and the island’s palpable sense of secrecy, where spirits, caves, and stone giants intersect in a landscape of memory.