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Jomon Period sea fishermen had thicker arm bones than those living inland: study

A male humerus bone from the Jomon Period, left, the thickest bone analyzed by researchers of the National Museum of Nature and Science, is seen next to a standard bone in an anatomical model. (Photo courtesy of the Kokai project)

TOKYO -- Ancient Jomon people living in coastal areas who fished at sea had thicker arm bones than those living inland, the National Museum of Nature and Science and other authorities disclosed.

Human leg and arm bones become thicker the more their muscles are used. While the legs and arms of the Jomon people tend to be thicker than those of modern people, it has been said that the areas where the Jomon people lived and their ages affected the thickness of their bones. The Jomon period runs from about 15,000 years ago to about 2,300 years ago.

After analyzing 797 humerus bones of the Jomon people, which were excavated from ruins around Japan, researchers at the museum found that a group of people, who had lived in coastal areas and had fished at sea, were likely to have thicker bones than those who lived inland. However, a group of people who had fished in rivers apparently had relatively thin bones even though they had lived near the coast.

Moreover, male bones unearthed at the Hobi shell mound of Atsumi Peninsula in Tahara, Aichi Prefecture in central Japan, were thicker than excavated bones in other coastal areas. The sizes of all the 22 bones from the Hobi shell mound were bigger than the national average, including the thickest bone unearthed in Japan. The thickest bone had a circumference of 8.1 centimeters, which is some two centimeters longer than the average size of male bones in the Edo Period (1603-1868).

The researchers believe that men living around the Hobi area trained their arms while rowing boats at sea for fishing and trading.

On the other hand, the study shows that the size of female bones unearthed at the Hobi shell mound did not differ in size much from those unearthed in other areas.

Yosuke Kaifu, who leads the museum's project to re-enact a voyage when Japanese ancestors came to the country more than 30,000 years ago, commented on the study, "It shows that there were no sailboats in the Jomon Period and the Jomon people could have rowed boats 30,000 years ago."

(Japanese original by Ai Oba, Tsukuba Bureau)

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