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Much ado about eating rats: sure Easter Islanders ate them, but there are more important parts to the story

October 11, 2013
ISU Marketing and Communications

Ancient Easter Islanders ate rats rather than seafood. This story didn’t make the cover of Rolling Stone, but it was picked as a “Coolest Science Story of the Week” recently by LiveScience.

People around the globe were recently informed that rats were a primary food source for ancient residents of the island also known as Rapa Nui in a story based on research done at Idaho State University that originally appeared on LiveScience (http://www.livescience.com/39926-easter-islanders-ate-rats.html).

That story went semi-viral and was picked up by websites and news outlets including, NBC, CBS and FOX news, the Daily Mail in the United Kingdom, USA Today, Huffington Post, Discovery News, Smithsonian and more. Easter Island is an isolated Polynesian island in the South Pacific and is a World Heritage Site famous for its monumental statues.

“I think all the attention on the study is overwhelming. It is not what I expected,” said ISU’s Amy Commendador, the lead author on the study “A Stable Isotope (δ13C and δ15N) Perspective on Human Diet on Rapa Nui (Easter Island) ca. AD 1400-1900.”

“What is ironic is that our study is not truly focused on the rats,” Commendador continued. “It does show that some people were eating rats, but that was definitely not unheard of in the Pacific Islands. Rats are a good protein source and they reproduce rapidly.”

“When you have few alternatives,” noted ISU’s John Dudgeon, a co-author on the study, “eating rats was probably an obvious choice. They were a lot more plentiful and easier to capture than seafood on this tiny island located in the far south of the Pacific, outside of that ocean’s richest waters in terms of sea life. Also, the island’s topography and lack of a developed reef system limited easy ocean access.”

“One of the upshots of the study is the recognition that they were very lucky to have brought rats with them, whether intentionally or accidentally,” Dudgeon said. “If they hadn’t, they probably wouldn’t have survived to be ‘discovered’ by European explorers on Easter Sunday, 1722.”

But the consumption of rats by the prehistoric population is only a portion of the puzzle the researchers are examining. What was more interesting to the authors is the heavier focus on terrestrial food sources overall rather than marine resources.

“Typically you expect to see more marine consumption, especially in the early phases of colonization of Pacific Islands,” said Commendador. “On Rapa Nui we only see strong evidence for seafood later in time, after around AD 1600. This doesn’t fit the subsistence model developed from archaeological excavations on the island, and opens the door to a host of new questions to address to fully understand what the islanders were eating and how and why that changed through time.”

“The study of Easter Island is really fascinating and a work in progress,” Commendador said. “There are a number of additional analyses we’d like to pursue, such as the potential for differential access to resources and the effect of a changing landscape on isotope values.”

The account in the decline of human population on Easter Island, from perhaps as high as 15,000 residents at its peak to about 2,000 to 3,000 residents when discovered by European explorers in the 1700s, has been well documented and studied. An account of it is included in the book “Collapse,” although the authors of this study believe this number may be seriously overestimated.

“There are a number of popular and historic accounts of ‘collapse” and changes to the population throughout prehistory and we are just one of several research teams actively trying to test and document the evidence for and implications of these scenarios,” Commendador said. “A lot of researchers think that residents consumed all the resources and collapsed on itself, but maybe instead we are seeing the story of a resilient culture that survived through a number of challenges over time.”

The ongoing ISU study is a “multi-effort collaboration” at ISU and other universities. The study was funded by the ISU Office for Research and Economic Development and was largely carried out ISU’s Center for Archaeology, Materials and Applied Spectroscopy (CAMAS) Laboratory. Commendador is the archaeological repository manager at the Idaho Museum of Natural History and a Department of Biological Sciences PhD student and Dudgeon is the CAMAS director and associate professor of anthropology. They worked with Commendador’s PhD advisor, Bruce Finney in the ISU Department of Biological Sciences , and colleagues in Hawaii and at the University of California Irvine.

The ISU researchers used the stable isotope mass spectrometer laboratory and other advanced instrumentation at CAMAS to analyze teeth and skeletal remains of past residents.

These discoveries give ISU researchers and colleagues many clues about the lifestyle and use of the land by the ancient inhabitants of Easter Island.


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