On the Sex Ratio of Population in Advanced Ages in Mountain Villages in Japan

Abstract

In Japan the ratio of newborn boys to girls is about 105 boys to 100 girls or 100 boys to 95 girls. This ratio approaches 1 to 1 with increase in age, and until World War II the attainment of this ratio of 1.00 occurred at about the age of 40 and in the ages above 40 the female population superpasses that of the male. The gradient of this predominance of the female becomes greater with advancing age.This increase of the female in population to the male with increase in age was disturbed a little after the War, but the ratio of newborn girls to boys is almost identical with that of former days.In 1952 and 1953 we carried on anthropological research in a remote mountain village Miomote, Niigata Prefecture and found that this sex ratio is deviated a little from that of the general population in the advanced age categories. The sex ratio (female to male) of population above 60 years there is about 0.5, namely 7 females to 13 males (see Table 1). We thought this was due to conditions of food and labour in this remote and retarded village, namely poorer food and heavier labour for women than for men. In 1956 we carried on researches in the mountain villages of Toga in Toyama Prefecture and Hinoemata in Hukusima Prefecture. These are also as remote and retarded villaes as Miomote. The results are shown in Table 1. Of these three the most retarded and remote is Miomote, the next is Toga, Hinoemata the least.For the sake of comparison, the census figures in the three Prefectures, Niigata, Toyama and Hukusima and in all Japan are shown in Table 2.It seems to us that the lesser ratio of the female to the male in the advanced age levels in mountain villages in comparison with those of plains villages and towns has some parallelism with their mountain village character, namely with decrease in the amount of level land and increase in the steepness of roads over which it is impossible to drive cars. The evidence is shown in Table 3 which compares census figures in Toga divided in 4 districts according to geographical conditions. Among them the worst conditions exist in Sorei, the next in Daikamba, while the best conditions exist in Toga and Momosegawa, above all Momosegawa has conditions nearly similar to those of plain districts and the sex ratio in the advanced age categories is elevated in this order.Relatively poorer food and heavier labour have caused higher death rates among females in comparison with that of the male in the advanced age levels in mountain villages. But this does not mean earlier deaths among females in mountain villages than occur in plains villages and towns, as is shown in the column for survival in the Tables. The base of this rate is the population in the years 0-9. The true survival rate is here noncalculable, because we had no census 60-90 years ago.