Nobody knows for certain when the first people settled the remote island of Rapa Nui, but the fall of Easter Island could be a cautionary tale for all. Between the years 1250 and 1500, nearly 1,000 stone heads known as Moai were raised across the island. During this time, Easter Island was a thriving hub in the southeastern Pacific, inhabited by the Rapa Nui people.
And yet, by the time of the island’s discovery by Europeans in the early 18th century, the island’s resources were dwindling and its population was moving towards a simpler, agrarian lifestyle.
By the end of the 19th century, as little as 111 native islanders were left on the island, down from as many as 3,000 a century earlier.
Long have researchers attempted to explain what happened to the Rapa Nui civilisation, finding fault in the slave trade, resource depletion and the introduction of European diseases.
A team of international scientists has now rejected two of the most popular theories and have, instead, attributed the gradual fall of Rapa Nui to a chain of events linked to climate change.
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Archaeological evidence shows the island was lush and covered with trees and a variety of plants when it was first settled.
All of that flora is gone, however, due in part to deforestation and the introduction of non-native species, such as the Polynesian rat.
Professor Mauricio Lima from University Católica de Chile in Santiago said: “The history of the population of Rapa Nui history has been quite controversial, and there have been two big hypotheses about its development.
“One of them is the ecocide hypothesis, stating that the population once suffered a big collapse because they overexploited the natural resources on the island.
“The other hypothesis is that a collapse occurred after the Europeans came to the island.
“Our research show that neither of these hypotheses are correct.”
The researchers gathered data such as climate variations in the Pacific, data from archaeological excavations as well as changes in population and agriculture over the centuries.
Their findings were then combined into a single model based on population ecology theory.
Professor Nils Stenseth, a biologist at the University of Oslo, said: “We have used this model several times before when we wanted to identify the reasons behind the changes in populations of other animal species like small rodents or fish species.
“This was a small human population on a small island with limited resources, and it seemed obvious that the model could produce interesting results.”
He added: “In order to understand what is going to happen with a population at a future point in time, you have to know what happened before.”
The Oslo researchers determined the decline of Easter Island is linked to the long-term effects of climate change on the island’s capacity for food production.
Easter Island, located just west of Chile, is strongly affected by the warming and cooling of sea temperatures, dubbed El Nino and La Nina, respectively.
And according to the new report, Easter Island is most sensitive to La Nina, which leads to decreased rainfall on the island.
The researchers found long-term patterns of rainfall over periods of about 400 years affected how the island’s populations grew and used up resources.
Professor Lima said: “The population on Rapa Nui lived — and live — on a small and remote island with limited resources, and we ourselves are living on a small and remote planet with limited resources.
“One of the lessons from this study is the importance of interactions between climate change, human population size and changes in the ecosystem.”
The expert added: “These three factors affected the population on Rapa Nui, and they are also important on a global scale.
“We studied Rapa Nui and its history because we are trying to understand what is happening with the planet.
“Everybody talks about climate change and the resulting problems, but very few people are talking about the rising global population and the problems it causes.”
Professor Stenseth agreed, saying: “The human population on Planet Earth is under the influence of ecological processes, just like any other animal species in a limited environment.”