One guess made by archeologists was that they were created as a way to celebrate important ancestors. They were made from 1000 C.E. until the second half of the seventeenth century. After the arrival and spread of Christianity, the standing moai were toppled or sent to the British Museum - only the buried heads remained.
It is true that archeologists had known about the bodies under the Maoi heads. In fact, the first expedition that had an excavation occurred in 1919. The problem is that expedition was poorly documented or had no documentation at all.
The Easter Island Statue Project (EISP), whose goals include the research, education, and conservation of the statues, has spent years documenting the nearly 1,000 statues on the island. When they released the findings of the excavations of two moai bodies in 2012, no one paid any mind, but things changed when team leader Jo Anne Van Tilburg posted photos on the team website. It got so many hits the EISP site crashed.
The images they posted were more than just massive bodies. The humanoid monoliths were covered in swirling designs and symbols. They still exist thank to being underground, away from centuries of strong winds and other elements.
These prehistoric rock carvings are called petroglyphs. The archeologists speculate that the designs on the statues might be similar to those of tattoos. One of the symbols is said to represent a canoe, or vaka.
The colors they found during the excavation also revealed something interesting about the Maoi. Many of the unearthed bodies contained red pigment. This meant that perhaps the Maoi statues were painted, and the rest was swept away from time.
While there have been many excavations throughout the decades, this one has made it more accessible to the public. Thankfully, the Maoi is not the kind of tourist attraction that attracts thieves. Its massive height and weight have kept them safe.
As for the mystery of how they got into their position in the first place, it was solved in 2012. An archeologist from California and an anthropologist from Hawaii put out a theory that Polynesians used ropes and a lot of manpower to move the massive statues back and forth for a walking effect. To prove their theory, they made a model of the statue, put ropes on it, and tried it out.
It's surprising to see that there are so many hidden layers to these iconic stony heads. Time may have taken a toll on them, and the civilization may have disappeared from collapse, but the documentation found has saved this lost wonder. And perhaps there are more mysteries to unlock from this monolithic culture.