October 20, 2010

Evidence Of Plant Food Processing 30,000 Years Ago

Grains of starch discovered on grinding stones suggest that ancient man may have dined on a type of bread at least 30,000 years ago in Europe, researchers reported this week.

The findings imply that processing starch grains, perhaps grinding them into flour, was a common practice throughout Europe during the Paleolithic era. 

If true, this contradicts previous beliefs among many researchers that prehistoric humans were primarily meat eaters.

The scientists recovered the grains from grindstones and pestle grinders at archaeological sites in Italy, Russia and the Czech Republic.  Each of the three sites was dated to roughly 30,000 years ago.

Researchers then analyzed traces of wear and residue on the grindstones and other tools by microscope, and conducted experimental reconstruction of how the tools functioned.

The grains appeared to come from starchy cattails and ferns, which are rich in starch and would have provided a substantial source of carbohydrates and energy, the researchers said.

"The wide size range and the different morphologies of the starch grains recovered (at two of the sites) suggest that they were used for grinding more than one plant species and possibly for other purposes," said the researchers, led by Anna Revedin of the Italian Institute of Prehistory and Early History in Florence, Italy.

However, "a large number of plant families are likely to have been involved in the diet."

To be adequately digested for its full nutrient value, the flour would have to be cooked after undergoing multi-step processing, including root peeling, drying and grinding into a flour usable for making cakes or flatbread, the researchers said.

Peeling and grinding the roots would also have allowed humans to make dried flour that could be stored and cooked later, perhaps to compensate for seasonal changes in food availability.

The study was published Monday in the journal Proceedings of the National Academy of Sciences.

Image Credit: Revedin et al.


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