Mystery solved? Researchers offer new clue to the perplexing origin of Easter Island statues

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The mysterious statues have puzzled researchers for years. 

Since European explorers first landed on Easter Island in 1722, people have been trying to figure out the meaning behind the hundreds of towering stone Moai monuments lining the island's shores. 

And now, researchers believe they may have figured out a key piece of that puzzle: why the massive heads are placed where they are, sprouting up sporadically across the island.

The answer, they say, is access to fresh water.

"What sort of struck us is that we really hadn't explored why did they do it where they did it," co-author Carl Lipo, an archeologist at Binghamton University, told As It Happens host Carol Off. 

"We thought if we could understand the context in which people were placing these monuments, we might learn a little bit about the logic about why they were doing this."

The sheer size and weight of the statues is unfathomable, Lipo says.

Some stretch as high as three stories and combined with their bases, which are called ahu, the statues can weigh as much as a 747 airplane. This is why Lipo says so much of the research until now has focused on the how rather than the why.

"These ahu reflect an immense amount of labour, moving multi-tonne blocks as foundations for these," Lipo said. "A lot of attention has been on how could they have done this."

Other hypotheses suggest that the statues were connected to some unknown ritual or used as idols built in what Lipo says has been referred to as "a mania of making statues."

But after reviewing the archeological record, Lipo and his team noticed the seemingly random locations of the statues might provide another clue.

When they started to research sources of drinking water, a pattern emerged. 

"Drinking water is notably not present on the island in form of streams and rivers," Lipo said. "So the question is where did you get your daily drinking water?"

After mapping the sources of fresh water, the team discovered that the majority of the sites were located near the coast and, repeatedly, next to the statues.

"Every place we saw massive amounts of fresh water coming out of the coast, right at the interface between the land and the sea, we would see a statue and an ahu," Lipo said. 

According to Lipo, the findings suggest that there is more to it than the statues simply marking the location of freshwater sources. He claims they played a key role in the daily activities of the community.

"It's telling us actually that the statues themselves were embedded into daily life of communities on the island and were key to their survival, rather than be some kind of extra ritual activity that was unrelated to daily life," Lipo said.

"These statues are connected to keeping communities co-operative, sharing resources, and making them more successful, which really explains how people were able to live on this island for 500 years despite its relatively limited resources."

Other researchers have taken issue with Lipo's findings.

Archeologist Jo Anne Val Tilburg told the Guardian that the freshwater locations were well-known and it's hard to believe they would be so important to merit a statue.

But Lipo says the importance of access to drinking water on an island cannot be overstated.

"Water on an island was a particularly important resource. You can't survive without it and you need to find those solutions for getting it on a reliable basis," Lipo said. 

Working with this new theory, Lipo hopes other pieces of the puzzle will fall into place, and he is already turning over new questions.

"The next question is why did some places invest so much into making even bigger ahu with up to 15 statues while other places were actually investing less?"

Written by John McGill. Produced by Tracy Fuller.