Rock Star : Archeologist Wins Acclaim for Theories on Easter Island Statues

In the end, it took Space Age technology to unravel the secrets of Stone Age technology.

That is how Malibu archeologist Jo Anne Van Tilburg apparently has solved a centuries-old puzzle over how primitive Polynesians were able to push and shove mysterious stone statues weighing as much as 89 tons all over rugged Easter Island.

It turns out that islanders may have used a system akin to present-day rocket-launch gantries to move the haunting statues--famed for their elongated faces and jutting chins.

Van Tilburg--who has spent 13 years studying the monoliths--has also discovered that there may be 300 more statues on the remote Pacific island than first thought.

Her findings are drawing international attention.

Last month they were the cover story in this country’s leading archeology magazine. Today, Van Tilburg leaves for Great Britain to lecture on the subject to the Royal Geographical Society and to autograph a book she has written.

Not bad for someone who was a bored homemaker before launching an archeological career by helping a friend hunt for artifacts at a Thousand Oaks construction site.

Van Tilburg had been a junior high reading teacher in South Whittier and an elementary school special education teacher before quitting work in 1974 to raise her newborn daughter, Marieka.

She acknowledges becoming restless by the time her daughter was enrolled in preschool. That is when one of the other preschool mother invited her to come help with archeological digging under way at the Prudential Insurance Co. office building site.

One day, the archeologist in charge of the Thousand Oaks excavation took the workers to Camarillo to look at Chumash Indian pictographs on a hidden outcropping of rocks.

“It was a turning point in my life,” Van Tilburg recalled. “You could see in the rock art what people were thinking and feeling. There were birds depicted, creatures flying, humans with light coming out their head and eyes. It was as if you were in church.”

She returned to college after that to study archeology and edit a book on Chumash pictographs. It was her interest in rock art that led Van Tilburg to Easter Island in 1982, where a fellow archeologist was studying island rock carving.

“The petroglyphs were interesting. But I fell in love with the statues,” Van Tilburg said. “They were literally strewn all over the island.”

Van Tilburg set out to find and catalogue each of the huge carvings--then thought to number about 600. Soon, she was directing a crew of archeologists and geologists searching ancient volcanic rock quarries and hillsides for signs of broken or unnoticed statues.

Now 80% complete, the project has turned up 883 statues--many whole figures that have been buried or hidden in the island’s lava-tube caves. They have been documented with more than 10,000 photographs and 4,000 drawings and maps.

Chiseled from volcanic tuff at three quarries over a 1,200-year period, the monoliths honored islanders’ gods and chiefs. Many were placed on stone platforms facing island homes.

But how they got there has been the subject of speculation for 273 years--since the first explorer dropped anchor off the island 2,200 miles west of Chile.

Some experts suggested that the statues were stood upright and slowly rocked back and forth by islanders pulling on ropes--much like homeowners can “walk” a bulky refrigerator across the kitchen floor.

Others postulated that the figures were placed horizontally on Y-shaped tree trunks and dragged over log rollers or inched along by being swung by rope from a log bipod.

“People had guessed and had personal theories, but nobody did the work we did,” Van Tilburg said.

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She started her work by taking measurements of more than 800 statutes. Cluster analysis of the measurements then done by Peter Christiansen of the UCLA biomedical research department concluded that statistically, the average statue was 14 1/2 feet high and weighed 14 tons.

After that, sketches were made of an actual statue that size by island artist Cristian Arevalo Pakariti. Those drawings were used by Los Angeles sculptor Gary Lloyd in producing a one-10th scale model clay sculpture that was laser-scanned and converted into a computer model.

Van Tilburg, meantime, was using osteological data to calculate the size of the “average” early Easter Island man. He was 5 1/2 feet tall, 150 pounds and about 24 years old, she concluded. That meant his daily nutritional requirement would have been 2,880 calories, allowing him to expend half of that in energy.

Her next step was to calculate how much energy would be needed to move the statues over the hilly island terrain. She turned for help to UCLA engineering professor Zvi Shiller--who 10 years earlier had devised a method for industrial robots to find “the optimum path” around obstacles in factories.

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Shiller conferred with experts in UCLA’s biology department to find the average maximum force that man can exert. Then he and his graduate students “went to the gym to see if the numbers made sense . . . the students used weights to verify how much you could push,” Shiller said.

By this time Van Tilburg was convinced that the statues were probably moved in a horizontal position--resting on parallel log poles wedged beneath them. The poles were then eased onto log rollers.

Because of the monoliths’ shape, the twin poles were probably positioned at a slight V angle. That made it easier for islanders to slide rocks and dirt under the poles to gradually hoist the figures upright at the end of the trip, according to Shiller.

By factoring together statue size, terrain roughness and pushing-force requirements, Van Tilburg gathered a wealth of information. It would take 63 people about 30 hours to move a typical statue 10 1/2 miles from the quarry to its ceremonial resting place. Raising the statue probably took another 30 hours, she said.

Van Tilburg said she is excited about her Royal Geographical Society lecture. “I’ll be standing at the same podium where Darwin and Sir Edmund Hillary stood,” she said.

She is also eager to resume her Easter Island research. She figures there could be as many as 200 more statues hidden on the 63-square-mile island, which natives call Rapa Nui. But it may take help from emerging “subsurface imaging” technology used by NASA to find them, she said.

Van Tilburg keeps her drawings, maps and measurements handy at her home overlooking the Malibu Pier. After the 1993 Malibu brush fire heavily damaged the living room of the house, she started keeping backup copies on computer disks stored by friends.

Her husband of 27 years--architect Johannes Van Tilburg--said her determined digging is worth it. “There are so many quasi-scientific articles done and Easter Island is always in them,” he said. “There’s a lot of misinformation out there.”

Experts say there is probably plenty more to learn about Easter Island statues, even though Van Tilburg has literally written the book on the subject for now.

“She’s probably the leading authority in terms of the statues,” said Pat McCoy, an archeologist for the state of Hawaii who extensively studied Easter Island 25 years ago. “We’re all waiting to see an experiment done on her hypothesis.”

Peter Young, editor of New York-based Archaeology magazine, said Van Tilburg is the first to use such a technical approach in tackling the island’s secrets. Archeology, he pointed out, is an evolving science.

“None of this is locked in stone,” he said.

(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)

Secret Unearthed? Malibu archeologist Jo Anne Van Tilburg used high- tech equipment to find what she believes is the answer to the centuries- old question of how hundreds of huge Easter Island statues weighing dozens of tons were moved by primitive Polynesians during a thousand- year period beginning about 400 A.D. Her theory: *

A. After being carved from a volcanic rock at quarries on the island, the monolith was moved on a primiive gantry. Long holding poles were pushed beneath the statue and then maneuvered across a series of roller logs.

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B. An average- size statue could be moved the 10 miles or so to its permanent resting place in six days if a crew of about 63 workers labored five hours a day. The log rollers were repeatedly moved and lashings holding the 14 1/2 foot- long figure to the poles were continually adjusted. *

C. At the site, workers placed rocks and dirt under the poles to slowly hoist the statue into place, usually on stone platforms overlooking islander’s homes. The slight V shape of the poles made it easier to erect the statue. This process took about 30 hours.