Washington, Mar 5: Ancient tartar encrusted teeth can be a biological gold mine for scientists studying food habits of prehistoric humans.

A new method developed for extracting food particles from prehistoric human teeth has already solved a mystery surrounding what early coastal Brazilians ate.

Scientists Celia Boyadjian, Karl Reinhard and Sabine Eggers of the Biological Anthropology Laboratory at the University of Sao Paulo, Brazil have created a new tartar extraction method, which involves a "dental wash" containing four percent hydrochloric acid as the main active ingredient.

To test the dental wash, the scientists gathered several teeth from Brazilian burials dating from 2,800 to 1,805 years ago. All were excavated at a southeastern coastal site called Sambaqui Jabuticabeira II.

The site has yielded several large piles of mollusk shells mixed with other debris, which are associated with human activity.

The researchers swirled recovered teeth in the solution to loosen the tartar. To isolate the particles in the tartar, the scientists strained and spun the solution in a centrifuge.

They found three types of microfossils. Most common were starch grains from tubers, diatoms and microscopic algae from marine organisms used as a food source, and phytoliths, tiny mineral particles produced by plants.

Researchers believe the first two microfossils suggest the individual's last meals likely consisted of shellfish accompanied by some sort of tuber.

"At the moment, we do not know where the phytoliths came from. They might have been part of a plant eaten or a plant element, such as palm leaves, chewed for the production of ropes, baskets, hammocks or some kind of clothing," Discovery News quoted Eggers as saying.

Although the dental wash was successful, it made some of the ancient teeth brittle, while others turned bright white.

So in order to leave the specimens in a condition as close to the original as possible, researchers have suggested improving the dental wash recipe.

Their findings are to appear in the Journal of Archaeological Science. (ANI)