LONG BEACH — For decades, researchers have been wondering about the mysterious stone statues on Rapa Nui, commonly known as Easter Island.
Why did the ancient Polynesian residents of the small island 2,300 miles from Chile build hundreds of stone statues of strange-looking faces?

And how did prehistoric islanders haul more than 25 million pounds of stone over distances of up to 11 miles?

Moving the massive statues, which weighed up to 82 tons, required more energy than did creating them, said Carl Lipo, professor of anthropology at Cal State Long Beach.

"It's like moving a 747 around the island," he said. "I mean, these things were huge."

Lipo recently shed some light on the question of ancient history with the help of a very modern tool — a commercial satellite.

Lipo and colleague Terry Hunt of the University of Hawaii used high-resolution satellite photos to trace nearly 20 miles of ancient roads on which the statues may have traveled.

His conclusions support a theory that some may find surprising. Small groups of people may have moved the colossal statues, rather than large armies under a central command.

The roads, which radiate from the island's quarry, were not constructed in any systematic way by a central authority, Lipo said. Instead, they appear to have been built as needed by small groups seeking to move a particular statue.

That conclusion is backed up by modern experiments that showed that as few as 20 to 30 people were able to move a statue using technology available at the time.

Families getting together
"It becomes more of a couple of families getting together to do this, rather than an army of people," he said.
But exactly how might the islanders have moved the statues along these roads? Experts don't know for sure, Lipo said. One possibility is that the islanders cut down trees to use as rollers.

The problem with the tree-roller explanation is that the species of tree on the island wasn't ideal for that purpose because it was spongy, Lipo said. Other scientists believe the islanders moved the statues by rocking them side-to-side like a refrigerator, he said.

Researchers still don't know for sure why the people built the statues. Another big question: What caused the collapse of the Rapa Nui civilization?

Were islanders so obsessed that they used up all the island's natural resources to build the statues? At some point, all the trees on the island had been cut down, a fact some researchers say caused environmental degradation and ultimately societal collapse.

Lipo and Hunt aren't so sure. They theorize that statue building may actually have been beneficial to the society -a smart way of maintaining the population and hedging bets against bad times.

Unpredictable changes
The more people on the island, the tougher it would be to deal with unpredictable changes in natural resources, Lipo said.
So how did statue building keep a lid on population growth? Lipo theorizes that islanders were so busy building statues that they didn't have the time to grow enough food to support an increasing population.

The obsession with statue building limited the food supply, and therefore population growth, he said, whether the islanders were conscious of it or not.

Diseases brought by Europeans may ultimately have led to the collapse of Rapa Nui society, Lipo said.

In 1862, Peruvian slave traders raided the island for workers, Lipo said. The Rapa Nui people worked on South American plantations and in guano mines, where they mined piles of bird feces, a source of fertilizer and fuel, he said.

A small number of natives were eventually sent back to the island. They brought European diseases that reduced the dwindling population there to less than 300 by the early 1900s, Lipo said.

About 3,000 people, including probably the descendants of those slaves, live on the island today, Lipo said.