For decades, Easter Island (Rapa Nui) has been used as a cautionary tale against humanity’s excessive use of the Earth’s resources. While there are varying hypotheses regarding what led to the local population’s collapse, it is largely accepted that unchecked deforestation was a large contributor. Other theories postulate that the Europeans’ arrival, around 1722, brought disease and slave trading to the island, or that stow-away rats decimated the island’s resources.
The truth, like the megalithic moai statues that decorate the island, has remained enigmatic. But with new analytic methods, scientists are digging for answers.
“In the last decade, there’s been a burst in new studies, including additional research sites and novel techniques, which demand that we reconsider the climatic, ecological and cultural developments that occurred,” said Valenti Rull, of the Spanish National Research Council, in a statement.
Russ and colleagues recently published an overview of the island’s sedimentary history over the past three millennia in Frontiers in Ecology and Evolution.
“These findings challenge classical collapse theories, and the new picture shows a long and gradual process due to both ecological and cultural changes,” added Russ.
Russ and colleagues claim that previous paleoecological analyses were hindered by extensive sedimentary gaps that hid a holistic view of the ecological trends occurring on the island.
The new research shows that forest clearing did not occur at a single time, but was a gradual process. In the Lake Raraku area, deforestation was marked by three periods: 450 BC, 1200 AD, and 1500 AD. Cultivation in the area was recorded around 1400 AD.
“Contrastingly, in the Aroi mire, located inland at higher elevations, a densification of the former open palm forests occurred at AD 1250, and the resulting dense forests were removed abruptly between AD 1520 and AD 1620, using fire,” the researchers wrote.
The sedimentary analyses also highlights wet and dry phases in the island’s climate history.
“Palm forests were almost totally removed from Raraku and Aroi in AD 1570 and 1620, respectively, before the end of the wet phase,” the researchers wrote. This was determined by a sharp increase in charcoal at both sites.
A drought occurred between 1570 and 1720.
“Wetter climates returned by AD 1720, close to the European arrival, which marked the onset of a genocidal cultural collapse,” according to the researchers.
They said the disappearance of the island’s original civilization can’t be explained by one sole factor. Likely it was a combination of climate, ecological and cultural factors.
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