Ecology of Easter Island When Polynesians First

¶ … ecology of Easter Island when Polynesians first arrived on the island about A.D.400, according to Jared Diamond?

At that time, Easter Island was subtropical with a mild climate. Its fertile soil should have made it a relatively easy place for humans to inhabit.

The island had a subtropical forest with low plants, ferns, many grasses, and tall trees, including fruit-bearing palm trees. This palm would have provided edible fruit as well as sap suitable for making sugar, sweet syrup and an alcoholic drink. The palm tree could grow to over 80 feet tall, and could have been used to build ocean-going canoes as well as to make stout rollers that could have been used to move the giant carved heads the island is so famous for.

What were the main sources of food eaten by Easter Islanders in the early yeas of island habitation?

They had fish hocks, so they must have eaten some fish. They grew bananas, taro, sweet potatoes, sugarcane and paper mulberry. They had chickens, and rats migrated with them, and they also ate rats. Based on bones found in archaeological digs, the Easter Islanders did not eat as much fish on this island as their ancestors did on other islands. However, they ate a lot of dolphins, meaning that at one time they had to have sturdy canoes. They also hunted a wide variety of sea birds as well as land-based birds such as owls and parrots. There was also evidence that they ate seal. All these foods were cooked in ovens that used wood from the island's forest as fuel.

3. What changes occurred in the Easter Island environment due to human exploitation? How did these changes affect the life and social organization of the Islanders?

The island's largest population may have approached 20,000, and it seems that when the Polynesians first arrived on the island, the island had enough resources to support a population that large.

Eventually, though, human habitation changed the ecology so drastically that the island appeared barren to first Western explorers. The Islanders' canoes were not sturdy and never could have survived the original ocean trip, which had to be thousands of miles because Easter Island is so far from other islands. Therefore how they built their boats must have changed since they originally arrived on the island. By the time Westerners found the islanders, the native canoes were made poorly and leaked badly, making them unsuitable for things like hunting dolphin some distance from the shore. This was because all the palm trees were gone. Evidence for this shows that the number of dolphin bones declined abruptly as the forest disappeared; the natives could no longer go to sea to hunt them.

In response the natives raised more chickens, and when that was not enough, resorted to cannibalism.

Pollen studies showed that plant life of all kinds declined over the centuries the Eastern Islanders exploited their environment. Other information showed that gradually the Islanders switched from using charcoal made from forest woods for cooking to sugar cane and grasses. This correlated with the decrease in tree pollen, suggesting that the fuel switch occurred because the forests had been severely depleted.

Another significant change in the island's economy occurred because the islanders introduced a foreign species to the island: rats. The rats chewed on the palm nuts, making it impossible for them to germinate. It is quite possible that rats contributed in a substantial way to the decline of the palm trees on Easter Island.

As it turned out, the statues were carved by opposing clans who used them as status symbols. They played an important role in society, representing wealth and power, so it was important that they be built and put in place. Logs from the palm trees were used to move them, contributing to the decline of the forests. Other tree products from other trees were used to make the ropes needed for this process as well.

As the natives ate up the local birds, cross-pollination performed by the birds may have declined.

4. How does Diamond explain the inability of Easter Islanders to see the effect they were having on their island's habitat?

Scarily, it happened gradually enough that they just didn't notice -- something that could easily happen in modern society as well.

The population grew, requiring more and more of the natural resources. Gradually they began cutting trees down faster than the trees could regenerate, aggravated at least some by both the action of rats eating or damaging seeds and by the decline in the bird population, which decreased cross-pollination. Forests were also cut down for farming land. As the forests declined the supply of water changed. Soil eroded. Art work from the end of the pre-Columbian period show figures whose ribs showed and who showed other signs of hunger. The society's previous centralized government fell apart and became more chaotic. Cannibalism filled at least some of the food shortage, and people took to hiding in caves to avoid marauding enemies whose goals now went far beyond carving a bigger effigy or knocking down the carvings done by opposing clans.

Population declined to as much as 10% of its peak (depending on what estimate of maximum population believed), to about 2,000 people. Clans destroyed each other's statues, knocking them off and decapitating them.

However, the changes that led to these calamitous events happened gradually and over time, hiding cause and effect between their immediate impact on the environment and the changes in that environment. The forest did not disappear rapidly but over generations. In addition, although Diamond did not note it, the Islanders may not have realized that the introduction of rats negatively affected the forest. They may not have known the relationship between birds and cross-pollination of plants and trees.

In addition, one use of the forest trees was intertwined with the power structure: those in power wanted the giant heads carved, and carving them contributed to the society's economy as it employed workmen such as the stone carvers who created them. They were important to the heads of clans who used them in their ongoing power struggles with opposing clans. Just as in today's society, being ecologically conservative interfered with the goals of some powerful people.

5. How does the Easter Island Case apply to what is happening in the world today?

As Diamond points out, if a small group of pre-industrial people working with stone axes could destroy the ecology of a fertile island that, better managed, should have supported them abundantly, it suggests that our technologically-rich modern society could cause an unrecoverable collapse of the Earth's ecology if we do not take aggressive actions to prevent that from happening.

CRITICAL RESPONSE: (one page)

It seems obvious that if a relatively small number of people with only rudimentary tools could virtually destroy an island's ecology in little more than millennia, that modern society could accomplish that task in considerably less time. The article's reasoning was persuasive: the researchers didn't just guess at what happened; they analyzed the changing bone remnants that demonstrated how they hunted and ate, talked to native Islanders about their cultural history and performed detailed studies of changing pollen as well as altered use of fuel over time. They considered the impact of the introduction of non-indigenous animals as well as how the natives' eating habits reduced the bird population.