Degenerative changes of the spine in people from prehistoric Okhotsk culture and two ancient human groups from Kanto and Okinawa, Japan

Degenerative changes of the spine in people of the Okhotsk culture were investigated in adult human skeletal remains from 38 males and 34 females. These findings were then compared with those in materials obtained from the medieval Kamakura period and early-modern peasants on Kumejima, Ryukyu Islands. The three samples clearly showed different patterns. In the Okhotsk series, the cervical spine of each sex had most osteophytes on the vertebral body, while the Kumejima samples had the highest frequency on the lumbar vertebrae. In the Kamakura series, males were most affected on the lower thoracic vertebrae. Moreover, severe osteophytes on the body of the lumbar vertebrae were more frequently seen in the Okhotsk males. Degenerative changes of the articular process of the Okhotsk series were most frequently seen in the lumbar vertebrae and least frequently seen in the cervical vertebrae. This is well contrasted with a high frequency of degenerative changes of cervical apophyseal joint in early-modern Kumejima peasants. The Kamakura series of each sex had generally low frequencies. Severe degenerative changes of apophyseal joint dominantly affected the Okhotsk series. It is inferred that different dynamic loads caused a high frequency of degenerative changes in the corresponding articular parts. For example, because the Okhotsk culture developed a considerable maritime infrastructure, the lifestyle required for sea-mammal hunting and fishing seems to have particularly affected the incidence of severe degenerative changes of the lumbar vertebrae.