Everyone knows the mysterious statues of Easter Island; almost nine hundred of them are dotted around the countryside, their impenetrable stares yielding up precious little information about their origins. But one of the great unknowns about how they came to be has less to do with the statues themselves than with the people around them.
When Europeans first came to the island's shores in 1722, they found hundreds of statues intact, but a population of only between 1,500 and 3,000; seemingly at odds with the vast number of monuments.
But now a new study, published in Frontiers in Ecology and Evolution, hopes to solve the riddle by establishing the maximum possible population size for the isolated island’s civilization in its heyday.
“It appears the island could have supported 17,500 people at its peak, which represents the upper end of the range of previous estimates,” said Cedric Puleston, lead author of the study, based at the Department of Anthropology at the University of California, in a statement.
“Despite its almost complete isolation, the inhabitants of Easter Island created a complicated social structure and these amazing works of art before a dramatic change occurred,” Puleston added.
“If the population fell from 17,500 to the small number that missionaries counted many years after European contact, it presents a very different picture from the maximum population of 3,000 or less that some have suggested.”
The researchers examined the potential for agriculture on the island before Europeans arrived to try and build up a picture of the number of people it could have sustained.
“We examined detailed maps, took soil samples around the Island, placed weather stations, used population models and estimated sweet potato production. When we had doubts about one of these factors we looked at the range of its potential values to work out different scenarios,” Puleston said.
Some 19 percent of the island could have supported a crop of sweet potatoes, the main food source for the indigenous population. The researchers then factored in information on birth and death rates to work out the largest number of people a crop on that scale could support.
Puleston said there was a wide variation in the possibilities, but added that the 17,500 figure is “entirely reasonable.”
“Easter Island is fascinating because it represents an extreme example of a natural experiment in human adaptation, which began when people from a single cultural group spread quickly across the islands of the Pacific,” Puleston said.
“The different environments they encountered on these islands generated a tremendous amount of variation in human behavior. As an extremely unusual case, in both its cultural achievements and its ecological transformation, Easter Island is remarkable and important. It retains an air of mystery, but it’s a real place and has a real history lived by real people. Dispelling that mystery brings us closer to understanding the nature of humanity.”