The main version of the decline in the population of Easter Island was called a myth

The main version of the decline in the population of Easter Island was called a myth
The main version of the decline in the population of Easter Island was called a myth
Anonim

Scientists built four models, and none of them supported the idea that the population of Easter Island experienced a demographic collapse before the arrival of Europeans in the early 18th century. Even if deforestation or fluctuating ocean temperatures affected Rapanui, its inhabitants were resilient to them.

Rapanui is a small volcanic island in Polynesia with an area of ​​164 square kilometers. Inhabited by Polynesian travelers between the 12th and 13th centuries AD, it is famous not only for its amazing megalithic structures, but also for its environmental changes that followed after the arrival of man there. Scientists have long argued about what happened on the island before the Europeans sailed there on Easter Sunday in 1722.

Central to this debate is the suggestion that the invasion of the Pacific rat and environmental degradation caused by deforestation and land clearing for agriculture have led to a demographic and cultural collapse. This hypothesis is also based on the fact that by the time the Dutch and then the Spaniards arrived, the population of Easter Island was already quite small and contrasted with its truly monumental architecture.

Scientists are discussing both the duration and the consequences of cutting down the palm forest that once covered the island. Probably, there was a real ecological catastrophe: the disappearance of trees caused large-scale erosion, soil depletion, and a reduction in the area of ​​surface fresh water bodies. As a result, there was a demographic decline.

Recent research also suggests that climate change took place long before the arrival of Europeans on Easter Island. Sediment cores from Lake Rano Raraku, for example, show a series of interruptions in sediment from the 15th to the 18th century: Rapanui Lakes are likely to have dried up as a result of severe droughts, potentially associated with the onset of the Little Ice Age or changes in the southern swing of the El Niño Current. "In the 15th century. Some scientists determined the conditional date of the collapse in 1680, others - in the 1430-1550s and 1640-1700s.

The picture shows the location of Rapanui in the extreme western part of Polynesia / © Nature Communications

However, new work by a team of anthropologists and archaeologists from Binghamton State University of New York, Cambridge, and the International Institute for Archaeological Research in Honolulu, Hawaii, insists that there was no ecological-demographic collapse on which the Easter Island hypothesis is based. The research results are published in the journal Nature Communications.

“Much of the scientific and popular debate about the island is centered around the idea of ​​demographic collapse, which supposedly correlates in time with climate and environmental changes,” the study authors said. - One argument is that changes in the environment have had a negative impact. People see that there was a drought, and they say, "Well, the drought brought about these changes." Yes, there were changes - in the population and the environment. Over time, the palm trees were lost, the climate became drier. But do these changes really explain what we see in the radiocarbon dating of Rapanui?"

One of the most common methods for reconstructing the extent of human activity at a given point in time is radiocarbon dating.However, standard statistical methods are not suitable for linking the obtained data to changes in the environment and climate. To do this, you need to estimate the likelihood function, which is difficult to calculate. Therefore, the authors of the study decided to apply approximate Bayesian computation, a form of statistical modeling: it does not require a likelihood function and provides a workaround.

Thus, scientists were able to discover that Rapanui experienced a steady population growth from the moment of its initial settlement in the XII-XIII centuries until its acquaintance with Europeans in 1722. Thereafter, two demographic models show a possible plateau in terms of population size, while the other two suggest a slight decline. They are all consistent with a logistic growth model that is only slightly affected by changes in climate and forest cover. It all follows from this that, even before the 17th century, more than a few thousand people never lived on Rapanui: their number increased rather than sharply decreased, and then reached a plateau.

There is no evidence that the disappeared palms provided food for the Rapanui. Deforestation did not lead to catastrophic erosion, because gardens appeared in their place, and agricultural productivity increased. During a drought, people may have relied on freshwater bodies off the coast. And the construction of the famous monolithic moai statues, which some call one of the factors of the collapse of Easter Island, continued after the arrival of the Europeans.

But why did the myth of Easter Island's decline become so popular? Researchers believe that this may be our own fault. The idea that changes in the environment inevitably and tragically affect the world's population began to unfold in the second half of the 20th century. Over time, it began to spread more actively, and as a result, scientists decided to view environmental change as the main factor in cultural shifts and transformations. However, this connection, according to the authors of the new work, is erroneous: they insist that it is impossible to transfer current climate problems to the past, looking at everything through one prism.

“We tend to think that in the past, people were not that smart and somehow made mistakes. In fact, the opposite is true. Although their technologies are simpler than modern ones, we still have so much to learn about the conditions in which they managed to survive,”the scientists concluded.

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