Conversation so far:
How is Heyerdahl related to the expedition of Easter Island?
Heyerdahl organized the Norwegian Archaeological Expedition to Rapa Nui (Easter Island).
Who went with him?
The expedition's scientific staff included Arne Skjolsvold, Carlyle Smith, Edwin Ferdon, Gonzalo Figueroa and William Mulloy.
When did they go?
In 1955-1956.
Was the trip a success?
The expedition published two large volumes of scientific reports.
Was this the only expedition to Easter Island?
In Easter Island: The Mystery Solved (Random House, 1989), Heyerdahl offered a more detailed theory of the island's history.
How well did his theory go over?
According to Heyerdahl, something happened between Admiral Roggeveen's discovery of the island in 1722.

Question: What else did Heyerdahl do?
Self-contained rewrite: Besides offering a detailed theory of the island’s history, what else did Thor Heyerdahl do?