The wind never seems to cease on Easter Island, and it whipped my hair into my eyes as I turned away from the enigmatic gazes of those mysterious giants and looked out at the vast ocean, trying to imagine, as have visitors and scientists before me, the lives of the ancient people who created such remarkable stone monuments. Before beginning this project, I had wondered why archaeologists didnât simply ask the islanders about their ancestors. I quickly learned that very little cultural knowledge remained, as the civilization that had existed for nearly a millennium was all but exterminated during the 18th and 19th centuries. By 1874 there were only 110 people left on the island, down from an estimated population of 12,000 at the societal zenith of the 1500s, a staggering and unimaginable loss. Though some oral legends and genealogy were retained and later recorded, most of what is known about the early civilization has been gained through patient archaeological excavation and restoration, which is precisely why our Earthwatch team was here.

Although the moai have received most of the worldâs attention, and thousands of hours have been spent on their study and restoration, they actually provide very few facts about the society that created them. The more telling but far less glamorous work is in understanding the day-to-day lives of people. Thatâs just what our leader, Dr. Christopher Stevenson, who got his doctorate from Pennsylvania State University in 1984 and has conducted research all over the world, has been doing here with Earthwatch teams for nearly 11 years. A regional archaeologist for the state of Virginia, Stevenson is also a renowned expert on Easter Island and has spent years making an extensive and detailed study of its settlement and agricultural history. Stevenson is, in fact, the first scientist to systematically investigate Easter Island settlements in great detail, and what heâs found has fundamentally changed our understanding of this enigmatic culture.

One of the questions Stevenson has been working on is how the early Polynesians had to adapt their traditional agriculture to the new conditions they encountered on Easter Island. I walked out with him one windy, overcast afternoon while he visually surveyed part of the Earthwatch work area, a small basalt quarry. He stooped to pick up a hand-chipped stone tool as I looked out across the landscape of golden grass and black volcanic stone and wondered how the people could have produced enough food. ãHow did they cope?,ä I asked him, as I tried to imagine myself growing a garden in that rock-covered soil. He explained that the first settlers had found an island that was very different from their homeland to the west (see the sidebar ãA World in Motionä): Where most Polynesian islands are warm, lush, and humid, Easter Island is cool and dry, has desiccating winds, a high evaporation rate from its volcanic soil, and no rivers or streams. The only reliable sources of fresh water for the settlers were the lakes found in the three volcanic craters, a few springs, and rain pools formed in lava tubes. At the time of the first landing, Stevenson went on to say, the island was forested with a now-extinct palm related to the Chilean wine palm (Jubaea chilensis) and the scrubby plant known as Sophora toromiro, as well as a number of as-yet-unidentified woody plants. The Jubaea palm nut was small and contained little edible material, and most of the other species consisted of ferns, reeds, and grasses. As for meat, there were about 25 bird species, few compared to other islands, and there were no indigenous land mammals. It may have been green, but it was hardly paradise.

Even the ocean, a traditional source of protein for Polynesians, provided fewer fish species because Easter Island has no coral reefs to mitigate the strong currents and heavy surf. As Stevenson put it, ãThere was no lagoon, so there was no large-net fishing, which the early Polynesians were accustomed to, only individual fishing, spearing, and netting. This really cut down on the amount of protein coming from the sea.ä The food plants they originally brought were taro, yam, banana, and sugarcane, as well as useful but minor plants such as paper mulberry (Broussonetia papyrifera), hauhau (Triumfetta semitriloba), and turmeric (Curcuma longa). They must also have included breadfruit, the basis of the Polynesian diet, but it was unable to survive in this cooler climate. The only food animals were the ones they brought with them: the small Polynesian chicken (Gallus domesticus) and the mouse-sized Polynesian rat (Rattus exulans).

Stevenson has proposed that for the first 300 to 400 years the people were subsistence farmers who lived within the larger bays for protection from the nearly ceaseless winds and who depended on the winter rains for their crops, as irrigation was impossible without streams. The soil on Easter Island, though somewhat nutrient depleted, could work for the dryland cultivation of taro and yams in family garden plots that lay fallow during the dry summers. ãAlthough the tubers were small due to the less-than-ideal conditions,ä Stevenson said, ãit didnât matter because they were still able to grow enough to feed themselves.ä The people also made forays into the upland areas to get reeds, palm nuts, and wood, and supplemented their diets with marine resources, which included sea slugs, sea urchins, small shoreline shellfish, and an occasional turtle or dolphin.

During the first several centuries, the monumental stone platforms, orahu, began to be constructed, and the first few moai were carved and erected. Dating Rapanui structures is very difficult and requires painstaking, detailed study, because all of the islandâs prehistoric man-made features were made from the ubiquitous lava stone, and their structure didnât change much throughout the centuries. Moreover, stones from older features were used to make newer ones. Stevenson is an expert at obsidian dating, a process he spent some time explaining to us. It allows man-made obsidian objects to be dated by measuring the rate at which water penetrates the glass after it is broken, and with it he has been able to date obsidian chips and tools found at ahu sites. ãThese obsidian tools,ä he says, ãplayed some sort of role in ahu construction, perhaps for smoothing rocks, cutting ropes, or even food preparation.ä But as important as obsidian dating is, Stevensonâs greater contribution to the understanding of Easter Island÷and the part where Earthwatch teams have been central÷is his ground-breaking study of settlement groups and agricultural techniques.

One gray day, our team of volunteers made our slow way across the rocky, treeless landscape to survey the area and mark with a yellow flag each human-made feature we found. Stevenson, wearing his usual Indiana Jones hat, followed with two other volunteers, Carlton Hershner, a retired mechanical engineer who, when at home in Maryland, is learning to juggle, and his wife Jean, a retired math and science teacher and a celebrated conservation volunteer. The Hershners measured the different lithic features while Stevenson described the features in detail in his notebook and conjectured their use. Soft spoken and easy going, he always gave clear answers to our questions and patiently described scientific findings in laymenâs terms. He carried an aerial photograph taken by the Chilean Air Force; mounted on a piece of Styrofoam and covering about 45 hectares to scale, it showed the larger natural and man-made features. Using these large features, he located the smaller features, such as house foundations and outdoor ovens and marked their locations, making a highly detailed settlement map.

Houses are one of the most important features Stevenson uses for determining settlement patterns, and our team found and measured many of their foundations. The early Rapanui lived in hare, ellipse-shaped houses about two meters wide at the center with narrow points on both ends. When in use, they were shaped somewhat like upside-down boats with thin uprights of arched branches supporting a roof of plant materials and with a pavement of smooth beach stones, or poro, in front. These huts generally were empty during the day, with everyone crowding in at night to sleep. Looking at the small size outlined in stone, I imagined how stifling the air must have been, and how often sleep must have been interrupted by crying children and people crawling in and out. Although the shape of the huts did not change significantly over the centuries, sometime around a.d. 1400, hare for chieftains and elite personnel began to appear. These houses, though not much larger than those of the commoners, had foundations outlined with long, deep lava stones, called paenga, which had been shaped and smoothed. Because of the time and effort required to carve them, archaeologists assume that these paenga represented social rank and wealth.

Besides the hare, common settlement features encountered throughout the island are hare moa, or chicken houses. Rectangular, five to ten meters long and one-and-a-half meters high, they have thick walls of volcanic rock with small window-like openings, a long, narrow interior chamber, and a stone roof that people likely used for sleeping or carving tools. Stevenson admits that even though they are called chicken houses, no one really knows how they were used.

Even more important than houses, though, is the question of agriculture. The two main problems the Rapanui had to overcome÷the two things that any visitor to Easter Island immediately becomes aware of÷were cold and wind, and the ways that they found to do that were remarkably innovative. Two common techniques were slope gardens, found inside ravines, and pu, depressions within rock concentrations at the foot of slopes. One afternoon we drove our rickety jeep along a barely visible path to a remarkable pu site several miles from the town of Hanga Roa. Quarter-moon shaped and about seven meters long, it was at the foot of a small natural promontory and completely covered with grapefruit-sized lava stones. Within the site was a significant number of depressions, each with a well-tended taro plant, and a series of tall stones that protected the plants from the wind. This site had probably been used continuously for hundreds of years, with people still returning to pull up the mother plant, remove the taro tuber, and replace the daughter plant for regeneration. I felt a strong sense of historical continuity as I stood on that ancient site with the wind whipping my hair, imagining the generations of Rapanui people who had tended the ancestors of those taro plants at my feet.

As the population grew and the people began spreading throughout the island, slope gardens and pu were a means of augmenting family gardens. By a.d. 1300ö1400, however, as the population began approaching its peak, the people had to find ways of growing food beyond the level of subsistence farming. Stevenson believes that this is when manavai began to be used. About one to one-and-a-half meters high and of varying widths, manavai consisted of a double wall of large lava rocks with an in-fill of smaller stones between the two walls. The thick walls enabled the structures to become heat sinks, creating a significant increase in temperature as well as protection against the desiccating winds. When Owen Jones, the photographer for this article, climbed into one, he said that he felt an immediate increase of perhaps six degrees Celsius.

Though clever and agriculturally important, even manavai and pu could not increase production enough to provide the surplus crops necessary for the growth in population and the crews building hundreds of ahu and moai during the peak years. The question of how these people were fed has been a major stumbling block for scientists. Then, five years ago, Stevenson made a startling discovery that solved the riddle.

On Easter Island, with its grass-covered lava fields and piles of black stones stretching in all directions, it is often difficult to distinguish what is natural and what is man-made, even for trained eyes. And that was just the case in 1995 as Stevenson excavated a rock field adjacent to one of the early settlement sites. He had assumed, as every archaeologist before him, that these endless fields of rocks were simply natural features, but as he excavated this site, he was surprised to find that there were planting pits beneath the surface stones. Then, the following year, archaeologist Joan Wolzniak, in her excavations on the west coast, found soil that shows signs of farming beneath large areas of lava stones. This confirmed that many of these fields of surface rocks were not natural but actually lithic mulch, put there by people to warm the garden soil and preserve water, thus increasing the cropsâ health and abundance.

ãLithic mulch is basically unknown in Polynesia,ä Stevenson says, ãbecause the other islands donât have the problem of moisture retention. As far as is known, this was invented by Easter Islanders.ä Stevenson and his Earthwatch teams have since discovered and mapped many such stone-covered plots, most of which were associated not with simple family gardens but with large fields controlled by members of the elite class.

Stevensonâs discovery has been key in understanding the most complex period of Rapanui history, a.d. 1425ö1680, during which the clans subdivided into approximately 11 political groups, each with its chieftain elite and a large religious center with ahu and moai. The technology of lithic mulch, along with the probable outside introduction of the hardy, cool-weather sweet potato (Ipomoea batatas), enabled the elite class to produce surplus crops that could be used for trading, alliance-building feasts, and providing food for the groups of carvers working on moai. By meticulously measuring, mapping, and dating settlement structures and gardens, Stevenson has been able to create a probable scenario for the development of Rapanui society: ãIn the beginning,ä he said, ãthe Polynesian institution of chiefdom was likely there, but weak, with no physical structures to mark an elite status.ä As the population grew and expanded across the island, the chiefs took on a stronger leadership role, and the elite strata began living in hare paenga. In order to validate their authority and that of their elite personnel, the chiefs must have needed the religious sanction that came through the power of the ancestral spirits; thus, they invested more resources in the building of ahu and moai, symbols that were associated with good fortune, economic bounty, and protection for the clan. Large lithic-mulch gardens provided agricultural resources, while other trade goods within clan boundaries were tool-quality basalt, obsidian, the volcanic tuff from which the moai were carved, and the red scoria for their topknots. Then the culture started to decline, and it is here that Stevensonâs findings are really coming into play.

If you read any popular account of Easter Island, and many scientific ones, they will say that the demise of Easter Island society began when the people cut down the last palm tree, which started a cascade of environmental and social disintegration. But thatâs not what Stevenson is finding. Pollen analysis from the Rano Raraku crater shows that the palm had nearly disappeared by a.d. 1100 and had become extinct by a.d. 1400. Yet, Stevenson says, the people flourished for another 200 years, reaching their cultural and religious zenith in the 1500s, and his discovery of the extensive gardens has revealed that food was plentiful during this period. Moreover, where many people have assumed that this deforestation of the palm brought about severe erosion, Stevenson has found in his study of agricultural sites that most of this expected erosion did not occur, probably because the native grasses and shrubs and the lithic mulch helped keep the soil intact. Thus, while the disappearance of the Jubaea palm may have caused some stress on the society, particularly with the loss of long pieces of wood for fishing canoes, the explanation that it caused the disintegration of prehistoric Rapanui society is, in the opinion of Stevenson and others, too simplistic.

There is no question, however, that a major upheaval in the culture did happen during the 18th century. The religious culture based on statue veneration and chieftain control disappeared, replaced by one controlled by warriors and centered around human fertility and the creator god Makemake. Rapanui society had been unusual in the fact that for hundreds of years warfare was either absent or extremely rare. Intergroup rivalry had been expressed in the construction of ever more splendid monuments and moai, but this construction had required cooperation, not warfare. Once the warriors had taken control in the early 1700s, however, there is evidence of persistent and violent territorial conflict. Weapons made from obsidian proliferated, settlement patterns reverted back to small family groups and garden plots, and people began taking refuge in underground caves and offshore islets. The most dramatic evidence is the widespread toppling of the moai from their platforms. This action must have required considerable effort, involving ropes, levers, and a number of men, and in many cases the statues were deliberately beheaded by placing stones where the fragile necks fell. What brought about the destruction of the chieftain society and its religious monuments? Widespread hunger was certainly one factor, as evidenced by scraps of oral legends and the undated wooden statuettes from the island, called moai kavakava, which depict men with hollow cheeks, a spinal ridge, and prominent emaciated ribs. Further evidence comes from Captain James Cook, who reported in 1774 that the natives were in poor condition: ãsmall, lean, timid, and miserable.ä

Stevenson believes that, in light of the innovative techniques of water control and moisture conservation practiced by the chieftain society, only a decline in total soil moisture could have caused such a food shortage. The likely cause, in his opinion, was the well-documented period of global cooling sometimes referred to as the Little Ice Age, which brought on a prolonged drought, one that even the Rapanuisâ ingenuity could not overcome. Once economic prosperity had declined and there was no more surplus food, the chieftain elite must have lost its authority and the symbols their sacredness. In that power vacuum, warfare was likely initiated as a means of obtaining and controlling the limited resources, and the society disintegrated into small, competitive groups. Then, in 1722, Europeans came, introducing European diseases that decimated the population, followed in the 1800s by Peruvian slave ships, which took most of the people who were left. The ancient Rapanui society which had produced these great and mysterious stone monuments slipped into historical oblivion.