Dental plaque from human teeth dating back to prehistoric Easter Island provided insight into the regional diet before European influence made its impact.
Easter Island is believed to have been colonized by Europeans in the early 13th century, these new findings help tell the story of what was like before that, the University of Otago reported.
In the past researchers have found evidence that palms were a staple of the Rapa Nui's (pre-Easter Island) diet, but these new findings suggest otherwise.
This new study spotted phytoliths (plant microfossils) embedded in dental calculus (hardened plaque) believed to be from palm trees. The teeth looked at in the study were from burial excavations that took place back in the 1980s.
"It is an excellent target for looking at the plant component of ancient diets as microfossils become embedded in dental calculus throughout a person's life. You can get a good idea of some of the plant foods people were eating, which is not an easy task," said Otago Anatomy PhD student Monica Tromp.
To make their findings researchers analyzed 30 teeth, looking for starch grains in the calculus. The team removed and decalcified the plaque from each individual tooth and identified starch grains that point to sweet potatoes as key part of the ancient people's diet. None of the observed starch was consistent with banana, taro or yam, other starchy plants that have been hypothesized to have been part of the early diet.
The team also tested the skins of modern sweet potatoes growing in the region, and found their skins incorporate palm phytoliths from the surrounding soil.
"So this actually bolsters the case for sweet potato as a staple and important plant food source for the Islanders from the time the island was first [colonized]," said Tromp, who worked with Idaho State University's John Dudgeon.
The findings were published in a recent edition of the Journal of Archaeological Science.
