Fossilized plaque, of all things, may have solved a mystery that has left archaeologists scratching their heads for years. Known for its iconic Moai statues, Easter Island is suspected to have been colonized around the 13th century. However palm trees, one of the only primary crops on the island, are believed to have become extinct not long after colonization. So how did the islanders survive?
A study recently published in the Journal of Archaeological Science details how teeth excavated from ancient Polynesian burials back in 1980 have been found to still contain evidence of palm - evidence that shouldn't have been there if the plants became locally extinct when experts are nearly certain they did.
So what's going on here? Further analysis of the fossilized tooth plaque, called dental calculus (no... not the math), also identified grains that best represent the modern sweet potato - a crop not even considered as an early food source on the island. Stranger still, none of the decalcified plaque samples showed any similarities to banana or taro, food crops that were hypothesized to move in on the advent of palm's extinction.
With this confusing set of new data, researchers Monica Tromp at the University of Ontago, and Idaho State University's John Dudgeon essentially decided to wing it and trust what they were seeing.
They went on to test modern sweet potato skins grown in sediment similar to that of Rapa Nui's (Easter Island) and found that as the tubers grow, their skins somehow takes on palm phytoliths that remain in the soil.
This could explain for the impossible palm data and "bolsters the case for sweet potato as a staple and important plant food source for the Islanders from the time the island was first colonised," Tromp said in a statement.
The researchers add that their study makes a strong case for the accuracy of ancient plaque sampling, where even nonsensical results can lead to some real answers.
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