Archaeologist Susumu Morimoto recently made a landmark discovery that could change today’s views of Japan’s ancient measuring system and of the Yayoi Period (300 B.C. to 300).

The head of the International Cooperation Section at the Nara National Research Institute for Cultural Properties discovered that what were believed to be grinding stones from the first half of Yayoi, about 2,400 years ago, are actually weights for scales.

“This would be my first and last discovery, and the greatest (in my life as a researcher),” Morimoto, 54, said.

“Compared with the continent (China), people back in that period are often considered barbaric,” he said. “But it may have been a more advanced era already with measurements and mathematics.”

Morimoto has said that the weights, with an accuracy of 99 percent, may have been used for trade and for items that could not be otherwise measured.

Morimoto had been obsessed with the 11 stones ever since he saw them about 30 years ago after they were excavated from the Kamei site in Osaka Prefecture, where there used to be a village surrounded by a moat during the Yayoi Period.

The cylindrical stones, which are 3 to 8 cm long with a radius of 1 to 4.5 cm, are more than 500 years older than the previous oldest bronze weights from the latter half of Yayoi that were unearthed from the Harunotsuji site in Iki, Nagasaki Prefecture.

Morimoto said he doubted the stones from the Kamei site were used as grinders because they looked different from any of the grinders he had researched and because he was unable to confirm any grinding traces.

To find what the stones were actually used for, Morimoto collected data and made calculations in the spring of last year that suggested they may be two sets of weights. He became more strongly convinced of this when he remembered weights from Mesopotamia he saw at the Louvre Museum in Paris in September 2010.

Morimoto said he hastily wrote a report on this assumption for presentation at the end of last year, but feared that “someone else may have already found it out as this seems too evident.”

A native of Tsu, Mie Prefecture, Morimoto became interested in the Paleolithic period when he was a sixth-grader and found his favorite books were reports on archaeological excavations.

He acquired his master’s degree in archaeology at Kyoto University and also studied in Belgium, before joining the Nara research institute at the age of 30.

Despite having little knowledge of computer programming, he learned to develop his own database and made one that lets researchers search for survey reports and unearthed artifacts across Japan.

Morimoto has also been involved in many projects to preserve archaeological sites overseas, having made more than 100 trips to Afghanistan, Cambodia and other countries.

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