Dirt: The Erosion of Civilizations - Kootenay Local Agricultural Society

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Pollen preserved in lake sediments records an extensive forest cover
when a few dozen people colonized Easter Island. The conventional story
is that Polynesians arrived in the fifth century and over the next thousand
years cleared the forest for agriculture, fuel, and canoes as the population
grew to almost ten thousand in the fifteenth century. Then, within a century
of the peak in population, a timber shortage began forcing people to
live in caves. Although recent reanalysis of radiocarbon dating suggests colonization
may have occurred centuries later, pollen and charcoal from sediment
cores indicate the island retained some forest cover through the seventeenth
century. The island was virtually treeless by the time the first
Europeans arrived. By then the last trees lay out of reach, sheltered at the
bottom of the island’s deepest extinct volcano.
Soil erosion accelerated once forest clearing laid the land bare. Crop
yields began to fall. Fishing became more difficult after the loss of the
native palms whose fibers had been used to make nets. As access to food
decreased, the islanders built defensive stone enclosures for their chickens—the
last food source on the island not directly affected by loss of trees
and topsoil. Without the ability to make canoes, they were trapped,
reduced to perpetual warfare over a diminishing resource base that ultimately
came to include themselves as their society unraveled.
Rapa Nui (the native inhabitants’ name for Easter Island) is located at
the same latitude as central Florida, but in the Southern Hemisphere.
Continually swept by warm Pacific winds, the island consists of three
ancient volcanoes occupying less than fifty square miles—a tropical paradise
more than a thousand miles from the nearest inhabitable land. Such
isolation meant that the island supported few native plants and animals
when wayward Polynesians landed after paddling across the Pacific Ocean.
The native flora and fauna offered so little to eat that the new arrivals’ diet
was based on chickens and sweet potatoes they brought with them. Sweet
potato cultivation took little effort in the island’s hot, humid environment,
leaving the islanders with enough free time to develop a complex society
centered on carving and erecting gigantic stone heads.
The monstrous statues were carved at a quarry, transported across the
island, and then capped by a massive topknot of red stone from a different
quarry. The purpose of the statues remains a mystery; how the islanders did
it was as much of a mystery for many years. That they transported their
immense statues without mechanical devices and using only human power
perplexed Europeans viewing the treeless landscape.
islands in time