Diet of Easter Islanders Revealed: Rats!
Cliff, CC Attribution 2.0 Generic, courtesy Wikimedia
The Polynesian rat (also known as kiore) is somewhat smaller than its Europeans counterparts and, according to ethnographic accounts, was tasty to eat. New research reveals that they formed an important part of the diet for the inhabitants of Easter Island.
Oct. 12, 2012
-- It might look like just an ordinary picture of Stonehenge, but this is how the creators of the prehistoric monument wanted the site to be viewed, according to research using the latest 3D laser scanning technology. The groundbreaking analysis determined that the prehistoric monument was built to show off the solstices. In this view Stonehenge would look best when approaching from the Avenue, its ancient processional way to the north east.
Commissioned by the English Heritage, the laser-scan survey revealed in unprecedented detail the efforts made by prehistoric people at Stonehenge. "The result of the project were beyond all expectations. The investigation identified traces of stone working on virtually every stone," Marcus Abbott, head of geomatics and visualization at ArcHeritage, Hugo Anderson-Whymark, an Oxford-based expert on ancient worked stone, and colleagues wrote in the English Heritage report.
The laser-equipped researchers investigated the entire site. The laser scanner collected data with a resolution of 1 mm across the entire stone circle, and of just 0.5 mm for four stone surfaces of special interest. More than 700 surface features came to light.
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The laser highlighted prehistoric carvings from 4,500 years ago as well as damage made by modern visitors. Along with modern graffiti, this image shows scores of little axe heads and a possible dagger added when the slabs were already 1,000 years old.
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Overall, the laser scanning revealed 71 new Bronze Age axe heads, which bring the number of this type of carvings known at Stonehenge to 115.
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But the most interesting findings came from analysis of the stone surfaces. The study showed that the techniques and amounts of labor used varied from stone to stone. According to the researchers, these variations provide almost definitive proof that it was the intent of Stonehenge's builders to align the monument with the two solstices along a north-east/south-west axis. Indeed, the extremely straight and neat outline of the Great Trilithon, compared with all the other trilithons, shows that Stonehenge creators made deliberate efforts to shape it more carefully due to its special position on the solstice axis, just as they did for other stones that flank this axis.
The laser scanning showed that sides of the stones that flanked the solstice axis were most carefully worked to form very straight and narrow rectangular slots. To make them glisten in the sunlight, some stones had their crusts removed. These stones include two of the north-east facing sarsens in the outer circle, the Great Trilithon in the inner sarsen horseshoe, and an isolated upright stone in the south-west segment of the outer circle. By contrast, the stones in the south-western segment of the circle did not have their crusts removed.
The specially smoothed slabs created a dazzling light effect when the sun rays hit the stones. They would glisten in the dawn light on the longest day of the year and at sunset on the shortest This drawing shows Stonehenge in about 2300 B.C., after the construction of the sarsen outer circle and trilithons. Note the solstice axis.
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The inhabitants of Easter Island consumed a diet that was lacking in seafood and was, literally, quite ratty.
The island, also called Rapa Nui, first settled around A.D. 1200, is famous for its more than 1,000 "walking" Moai statues, most of which originally faced inland. Located in the South Pacific, Rapa Nui is the most isolated inhabited landmass on Earth; the closest inhabitants are located on the Pitcairn Islands about 1,200 miles (1,900 kilometers) to the west.
To determine the diet of its past inhabitants, researchers analyzed the nitrogen and carbon isotopes, or atoms of an element with different numbers of neutrons, from the teeth (specifically the dentin) of 41 individuals whose skeletons had been previously excavated on the island. To get an idea of what the islanders ate before dying, the researchers then compared the isotope values with those of animal bones excavated from the island. [Photos of Walking Easter Island Statues]
Additionally, the researchers were able to radiocarbon date 26 of the teeth remains, allowing them to plot how the diet on the island changed over time. Radiocarbon dating works by measuring the decay of carbon-14 allowing a date range to be assigned to each individual; it's a method commonly used in archaeology on organic material. The research was published recently online in the American Journal of Physical Anthropology.
The researchers found that throughout time, the people on the island consumed a diet that was mainly terrestrial. In fact, in the first few centuries of the island's history (up to about A.D. 1650) some individuals used Polynesian rats (also known as kiore) as their main source of protein. The rat is somewhat smaller than European rats and, according to ethnographic accounts, tasty to eat.
"Our results indicate that contrary to previous zooarchaeological studies, diet was predominantly terrestrial throughout the entire sequence of occupation, with reliance on rats, chickens and C3 plants," the researchers write in their journal article, noting that the resources from C3 plants (or those that use typical photosynthesis to make sugars) would have included yams, sweet potatoes and bananas.
The islanders' use of rats was not surprising to the researchers. Archaeological excavations show the presence of the Polynesian rat across the Pacific. The Polynesian form commonly travels with humans on ocean voyages and, like any other rat, multiplies rapidly when it arrives on a new island. In some cases, the rats were probably transported intentionally to be used as food, something supported by ethnographic accounts stating that, in some areas of Polynesia, rats were being consumed at the time of European contact. Additionally, previous research has suggested the rats were at least partly responsible for the deforestation of Rapa Nui.
Chemical analyses of teeth from 41 human skeletons excavated on Easter Island revealed the inhabitants ate rats rather than seafood.Amy Commendador
What was more surprising to the researchers was the lack of seafood in the diet of the islanders. "Traditionally, from Polynesian cultures you have a heavy predominance of using marine products, especially in the early phase of colonization," said Amy Commendador, of the Idaho Museum of Natural History at Idaho State University, in an interview with LiveScience.
One reason for the lack of seafood may have to do with the island's location and topography, Commendador said. The northern end contains steep cliffs and would be difficult to fish from. Additionally, the island's southerly latitude makes it somewhat cooler and may affect fishing. "Because of their geographic location and climate conditions, there just weren't as many marine products for them to get," Commendador said.
Rats should not be underestimated in their value as a resource, study co-author John Dudgeon, also at Idaho State University, told LiveScience. They could eat anything and multiply rapidly within a few generations. For the people who lived on Rapa Nui, "it was probably easier to go get a rat than it was to go get a fish," Dudgeon said.
Though the study results showed the islanders' diet was mainly terrestrial, a few individuals, dating after A.D. 1600, appeared to have been eating more fish than the others. [The 7 Perfect Survival Foods]
These fish eaters may have lived on a part of the island where the fishing was easier, Commendador suggested. Another possibility the team raises in their paper is that access to marine resources varied due to the social and political constraints people faced. For the islanders, eating fish might have been a mark of "higher status" individuals, an elite person who was allowed more plentiful access to seafood.
One curious coincidence is that most of the Moai, the statues erected by the islanders, face inland rather than out to sea. Now, this new research suggests the people of the island also turned inland, rather than to the sea, to get their food.
Commendador and Dudgeon don't think any direct relationship between the Moai statues and the islanders’ diet exists. Previous research has suggested the statues were positioned facing inland due to ancestor worship, so that the statues could watch over their descendents.
Another, more speculative, idea is that by having the statues facing inland, the islanders were also "saying we're turning inwards and not turning outward," Dudgeon said. While this probably doesn't relate to the islanders' decision to eat rats rather than fish, it shows the mindset the people of Rapa Nui may have developed before the arrival of Europeans. Their lifestyle as well as their diet may have become focused on the land rather than the sea.
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