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.