Easter Island’s Silent Giants: New Clues to a Lost Civilization
The fate of Easter Island offers a warning to humanity about the disaster caused by unsustainable resource use.
The accepted theory is that the arrival of the first Polynesians on the tiny island in the 1200s led to rapid deforestation to build the moai stone statues. The famous carvings are massive, up to 40 feet (12 meters) tall and 75 tons in weight.
The rapid environmental change led to a population collapse before the arrival of Europeans in the 1700s. According to scientists, the Easter Island statues are a warning against overexploitation of the natural world.
But archaeologists have recently challenged this theory of social collapse on Easter Island. Instead, researchers have looked at factors such as drought that could have led to catastrophic shifts in Rapa Nui culture.
William D’Andrea of Columbia University in New York and colleagues analyzed hydrogen isotopes in the waxy coating of ancient leaves preserved in lake sediments spanning the island’s occupation history.
The amount of such isotopes in the leaf wax closely correlated with changes in local precipitation, giving the researchers a tool to estimate past changes in rainfall on the island.
The data showed that the island experienced significant drought between 1550 and the early 1700s, with rainfall dropping by as much as 900 millimetres per year during that period. For example, the drought between 2010 and 2017 on Rapa Nui severely reduced freshwater supplies, with annual rainfall falling by 370 millimetres.
The authors of the new study believe that the drought coincided with major changes in Rapa Nui society, possibly triggering a decline in stone statue building.
“Our hypothesis does not require a violent war or demographic collapse in 1600 CE, but provides a reasonable explanation for possible causes of intercommunal conflict,” the study’s authors write.
“Droughts do happen on Rapa Nui, and they can be really dramatic,” says University of Alaska Fairbanks geologist Daniel Mann, who was not involved in the study.
But not all archaeologists agree that drought was the main cause of conflict or cultural decline.
The drop in rainfall could have had a negative effect, says Carl Lipo, an archaeologist at Binghamton University in New York. But there is no evidence of dietary stress in the skeletons of people from the period, nor any sign that work stopped at the quarries used to build the statues.
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