In the history of Japan, there have been 10 instances of females ascending the imperial throne, beginning with the first-ever female emperor, Suiko (554-628).
Two of the 10 were special cases of acceding for a second time or assuming the throne again after abdication, so the actual number of females who ascended the throne was eight. Two instances of female emperors occurred in the 17th and 18th centuries. The remaining six cases took place during an intense period in the sixth and seventh centuries, beginning with Emperor Suiko.
Why were there so many female emperors in those times?
According to one theory, it had something to do with the fact that the blood lines of many powerful clans, such as Soga and Fujiwara, had flown into the imperial family. Because of power struggles among the influential clans, a decision couldn’t be reached on who should be the next-generation emperor in the male line. Female emperors therefore emerged in the capacity of relay successors, reigning until the next male emperor could be chosen, or so the theory goes.
In addition, there were cases in those days in which an emperor succumbed at a young age. In some such cases a female emperor served as a relay successor when the crown prince — the next in line to the imperial throne — was a child, or a suitable successor could not be identified immediately.
Inheritance of Chrysanthemum Throne Transcends Times
Noteworthy in this connection is the hard fact that, although there did exist female emperors, there never existed even a single emperor who descended from the female imperial line.
While there were cases in which females ascended the throne as relay successors, the imperial lineage has been inherited through the male line on a continuous basis. There was no instance of the sex chromosome of Y — which is passed on from the father only to his sons — having been discontinued or altered to another chromosome.
Human beings have 22 pairs of autosomal chromosomes and a pair of sex chromosomes. Sex chromosomes were a combination of X and X for women, while that for men are X and Y.
Since the autosomal and sex chromosome for women come in the state of pairs, chromosomal crossovers take place when reproductive cells are created. That is, there emerges a chasm somewhere in the sequence of the chromosomes, leading to an exchange of genes.
By contrast, the sex chromosomes for men, X and Y, do not form a pair. Because of this, no chromosomal exchanges take place. (To be exact, however, male chromosomal crossovers can happen at the periphery, but they never happen at the rest of the male sex chromosomes.) Consequently, the chromosome of Y as handed down from the father to his sons stays pretty much the same.
While genes on the sex chromosomes of X and autosomal chromosomes change as they break apart over generations, those on the Y chromosome have been persistently preserved.
So far, as Japan’s imperial family is concerned, virtually the same Y chromosome has been inherited, to the best of our knowledge, for at least 1,000 and several hundred years. There is no other country in the world that is comparable to Japan in this respect.
Significance Understood Before the Age of Genetics
There were some occasions in Japan’s history in which there was no male in direct line with deep blood ties to the emperor — for example when an emperor had no son, or his son died at a young age and the emperor had no brothers. Despite such circumstances, the imperial throne was inherited by tracing the emperor’s family tree to ascertain a male with the imperial Y chromosome.
One may well wonder why such unerring judgments were possible in ancient times when nothing was known about chromosomes and genes. Possibly, many in those days shared the awareness that something special would be genetically conveyed from a father to his sons.
Differences of the British Royal Family
Even the British royal family has a history short of 1,000 years. Their history commenced with the enthronement in 1066 of Duke of Normandy, who was one of the feudal lords of France.
Worthy of note, when a queen of the British royal family was enthroned, the throne next to hers was mostly inherited to her son, so that the sex chromosome of Y was replaced with the one for the husband of the queen. Probably because people in that country were aware of this, the change in the Y chromosome was followed by a change in the name of the dynasty after the queen’s husband.
There is an anecdote of interest regarding Britain’s existing dynasty, the House of Windsor. When Edward VII, the eldest son of Queen Victoria, ascended the throne in 1901 after the queen’s death, the dynasty took the name of the queen’s husband Albert’s family home in Germany. As Germany became an enemy country of Britain in World War I, the dynasty’s name was changed to Windsor in tribute to the name of its castle.
Y Chromosome’s Strength and History of its Inheritance
We should never quit hold of the Y chromosome that has been inherited ceaselessly down the line of the imperial family for 1,000 and several hundred years. Japan’s history of the inheritance of the strongest Y chromosome on earth is one that no other country has the means to emulate.
It is widely known, however, that inheritance through the male line has been in jeopardy recently. There are only two members of the next-generation of the imperial family with the Y chromosome, Crown Prince Akishino, who is first in the line of succession, and his son Prince Hisahito, the second in line.
Should Prince Hisahito not be blessed with a son, the possibility of extinction of the imperial line would arise. The entity known as the origin of the authority of this country would be at risk, threatening an end to Japan as it has been for over a thousand years because there would be no heir to the imperial throne.
Preventing Extinction of the Imperial Line
One ray of hope lies in the possible restoration of former imperial branch families that were divested of their imperial status on orders from the general headquarters of the occupation forces after the end of World War II. There are males with the imperial Y chromosome among the members of those branch families.
Originally, the imperial relationship of the former branch families was maintained for the sake of ensuring the male-line imperial lineage. Their post-war demotion from nobility to commoners is a cause of the current crisis.
Japan’s new era name, Reiwa, has been drawn from one of the nation’s classics — the Manyoushu — for the first time in history, rather than from Chinese classics, as was the case with the past era names. This marks a departure from Chinese influence when it comes to the nomenclature of Japan’s eras.
In keeping with this approach, it may be advisable to allow members of former imperial branch families to return to imperial status to sweep away the GHQ influence.
At a minimum, the return of branch family males with the imperial Y chromosome should be facilitated to allow continuation of the imperial line. This should happen even if it is practically difficult to return former branch families to imperial status en masse.
The Japanese people’s understanding of the deep significance of the inheritance of the imperial throne by a descendent of the line of males is necessary to conquer the crisis now facing the imperial family.
(This article was first published in the May 15, 2019, “Seiron” column of The Sankei Shimbun. Click here to read the original article in Japanese.)
Follow this link to read more about the Japanese imperial system and the new era of Reiwa.
Author: Kumiko Takeuchi, essayist and animal ethology researcher