<論説>古病理学的ストレスマーカーが示す江戸時代人の健康と男女の格差 (特集 : 病)

Abstract

江戸時代、東北北部太平洋側の地域は、度重なる「やませ」の影響を受け、飢饉に苦しめられた地域であった。ここから出土した人骨を調べたところ、古病理学的ストレスマーカーであるエナメル質減形成を認めた。その出現率や重症度は、他の地域集団よりも高く、この地域の人々は深刻な低栄養状態を経験した集団であることが、骨から裏付けられた。また、エナメル質減形成の出現率は、地域集団により男女差の有無が異なり、男女差がある理由として家父長制の浸透による女性の地位低下の傾向が指摘されている。しかし、この地域では出現率に男女の差は無かった。家の継承を重視し男児が尊重されていた江戸時代にあって、性別による出現率の差が無い事実と、エナメル質減形成の出現率の高さ、重症度の高さから、この地域の人々は、生き残るという最重要課題を前に、性別で区別されることなく育まれた人々であった。

Japanese people in the Edo period repeatedly suffered from famine as a result of natural disasters and weather conditions. Areas such as the northern part of the Pacific Ocean side of the Tohokuregion (the northeastern part of Honshu) were stricken especially by famine due to the repeated impact of the yamase, a cold northeast wind observed during the rainy season and in the summer in regions on the east and north side of Hokkaido and on the Pacific Ocean side of Honshu. Yamase originally referred to a cold and wet wind associated with fog. With the lack of sunlight due to this condition, agricultural crops were seriously damaged due to the cold weather caused by long periods when the yamase prevailed. The Hachinohe domain, which dominated the region and which was located in the area extending from current Aomori prefecture on the Pacific Ocean side to the northeast part of Iwate prefecture, is the location where human bones used in this research were excavated. It suffered climatic damage in about half of the 200 years from establishment of the domain to its termination. According to records, the population of the domain decreased by 30, 000 or more due to famine and the population was halved in a single year. It was assumed that people had been forced to live a life associated with physical stress regardless of gender in such regions. On the other hand, it is also believed according to an accumulation of many studies of women's and literary history that the tendency for the status of women to decrease grew stronger during the Edo period. A primary reason for the decline was the spread of The Great Learning for Women (Onna Daigaku), a book that spelled out a wife's duties during middle and late Edo period. For example, it instructed a woman to give priority to serving her husband's family, taming her ego in marriage, and obeying her father, husband and children at each stage throughout her life. Since The Great Learning for Women dispensed the philosophical concept that a family should be headed by the first son in order to maintain the system of control in the samurai-led society under the Tokugawa Shogunate, the impact was remarkably strong among the samurai class. With the spread of this educational philosophy from the samurai class to farmers, women were seen as daughters-in-law belonging to the family and wives belonging to husbands even in rural areas. In consideration of the fact that there were some cases in which women served as the head of a family even this rural area, however, it has been pointed out that status of women varied depending on the social situation to which women belonged such as the status hierarchy, the region or styles of working. In the current study, we have surveyed a cluster of human bones excavated from three sites on the Pacific Ocean side of Aomori prefecture. One result was the appearance of a high ratio of enamel hypoplasia. This paleopathological stress marker, which includes reduction defects of enamel, has been widely used as a benchmark of the health condition of excavated human bones in epidemiological investigative research of modern human populations. It has been confirmed by these bones that the population of this region experienced seriously low nutrient conditions due to the higher ratio and degree of severity of reduction defects of enamel compared with other regional populations. In a previous study performed using human bones excavated in the Edo period, the reduction of women's status was pointed out as a reason for the different ratio of the appearance of stress markers observed between men and women in the regional population. However, the difference in the ratio of the appearance of enamel hypoplasia was not observed between men and women in people of this region. In consideration of the regional characteristics of the Aomori population in whose environment famine was more likely to affect the body, the fact that no difference in the ratio of enamel hypoplasia appears between men and women along with its high ratio of it appearance as well as the degree of its severity have great significance. In other words, the concept of the dominance of men over women had become common in many regions during the Edo period due to the importance of family inheritance, however, people in the Aomori population made survival a priority at any cost because they lived in a harsh environment leaving no room for adherence to rules of family inheritance or maintenance of the principle of men as heirs. It may be said that people in this population were carefully nurtured and survived in the sense that all lives were preserved whenever possible regardless of gender.