When the first European boats arrived at the remote shores of Easter Island in 1722, the native community there was but a shadow of its former glory. Due to centuries of unsustainable deforestation and farming practices, the islanders had depleted their natural resources and the population had been experiencing a slow decline by the time they made contact with Europeans. For this reason, Easter Island is often used as a historical anecdote for the environmental calamities that threatened us due to climate change.
However, a group of researchers from Binghamton University, State University of New York beg to differ. Their research suggests that Eastern Island natives hadn't experienced demographic collapse. In fact, their numbers were as high as ever when Europeans landed on the remote island's shore. If anything, Easter Island should be used as an example of resilience rather than disastrous collapse, the researchers argued in a new study published in Nature Communications.
Easter Island: a story of resilience?
The island famous for its 70-ton carved statues was first settled around the year 1200 AD. When the first people arrived on the 63-square-mile patch of land, the place was covered with as many as 15 million trees.
But the settlers, who were slash-and-burn farmers, burned down most of the woods to open up space for crops and gather building material. Within a couple of generations, the island reached an unsustainable number of people, about 3,000 to 4,000 people at its height, and too few trees, according to one often-cited estimate presented in the best-selling book, Collapse, by author Jared Diamond.
Such conclusions are the result of demographic reconstructions based on archaeological evidence and estimations of environmental change during certain periods of the island's history. For instance, scientists know that around the year 1500, more than two centuries before the natives made contact with European settlers for the first time, the island went through a climactic shift known as the Southern Oscillation Index, which caused the climate to dry.
By counting burials sites and measuring ancient homes, it is possible to estimate a population's size over its history. But a more established technique uses radiocarbon dating to track the extent of human activity during a certain moment in time. If there is a lot of activity, then this is a sign of a larger population.
"One argument is that changes in the environment had a negative impact. People see that there was a drought and said, 'Well, the drought caused these changes,'" said Carl Lipo, a professor of anthropology and environmental studies at Binghamton University, State University of New York. "There are changes. Their population changes and their environment changes; over time, the palm trees were lost and at the end, the climate got drier. But do those changes really explain what we're seeing in the population data through the radiocarbon dating?"
Reconstructing Easter Island's population
Lipo and fellow anthropologist Robert DiNapoli, who is the lead author of the new study, aren't at all convinced by previous population assessments on Easter Island using radiocarbon dating, which they call uncertain.
Using a statistical method called Approximate Bayesian Computation on radiocarbon and paleoenvironmental records, the researchers paint a different story of how the population varied in size relative to environmental variables such as instances of climate change.
Unlike traditional statistical methods that break down when computing population shifts as a function of environmental change, Approximate Bayesian Computation can model population change with less uncertainty, the researchers claim.
Their analysis suggests that, contrary to previous findings, the island actually experienced steady population growth from its initial settlement until European contact roughly 500 years later. After this initial point of contact, the population either plateaus or declines, according to the outcomes of four different models computed by the authors of the study.
To support their conclusions, DiNapoli and Lipo point to recent evidence showing that deforestation on the island was prolonged rather than sudden and that it didn't result in catastrophic soil erosion since forests were replaced by vegetable gardens that contained stones whose minerals increased agricultural yield. During droughts, the natives could have relied on freshwater coastal seeps. New Moai statues continued to be erected on the island even after European contact.
"There's a natural tendency to think that people in the past aren't as smart as we are and that they somehow made all these mistakes, but it's really the opposite," Lipo said. "They produced offspring, and the success that created the present. Even though their technologies might be more simple than ours, there is so much to be learned about the context in which they were able to survive."
The researchers argue that the idea of Easter Island's collapse at the hand of unsustainable practices and climate change is a myth -- and a very entrenched one to boot since people are attached to the idea of humans destroying themselves in the context of the post-industrial destruction we've caused and anthropogenic climate change. But despite the very real threat of man-made climate change, we shouldn't let our judgement regarding historical contexts be clouded by present reality. Instead, Easter Island could very well be seen as a story of resilience.
"Those resilience strategies were very successful, despite the fact that the climate got drier," Lipo said. "They are a really good case for resiliency and sustainability."
Of course, not everyone is convinced. There are still many scientists who believe that the Easter Island native practices led to the collapse of their civilization. We will likely have more to learn about this mysterious island and its people.
The findings appeared in the journal Nature Communications.
