You know, back when my Daddy was born at the turn of the 19th to 20th centuries, the average age a male child born that year could expect to live to was. . .47. In the US.
You know, back in the days when knights were bold, in the 14th and 15th centuries in Europe, those mighty knights BARELY topped 5 feet tall. Their ladies were even shorter.
The point is that in ‘the old days’ people lived shorter lives. The woman in the 6th-15th centuries per studies chronicalling life in Medieval Society had menarche averaging from age 12 to 15, the earlier range in the Mediterranean countries, and also among non-white women, and married earlier especially in the ‘upper ranks’ and had an earlier menopause in many cases especially if the diet was meager and/or the woman’s activity level was high. We see this phenomenon of an early cessation of menses today in girls who exercise to excess and also those with anorexia and bulimia, who often experience clinical amenorrhea.
It may seem that a menarche in the age range of 12-15 or so is not ‘earlier’ than today’s standards, but rather fairly similar. However again, in the early Industrial Age and especially in the West the age of menarche often went slightly up, with some women not achieving menarche until the age of 16 or 17. This age range was one with which my grandmothers, all born in the Years around 1870, were familiar with. My mother and her sisters, born in the 1920s, experienced menarche at age 16, and that was not considered abnormal in the least for the 1940s.
Further, while menarche in later centuries until the late 19th century actually among large groups of women increased, often to the ages of 15-17, this later menarche in many areas of the world over the 20th century appears, according to many studies, to have somewhat reversed, to the point that today it is claimed that the average Western girl’s menarche average is about the age of 12-1/2, with the range being 11 to 14-15.
Childbearing was taken seriously.
And as others have noted, children were not ‘children’ the way we know them. Once a child was weaned, no longer breast feeding, around age 2 or 3, he or she was put into ‘leading strings’, and started to have chores. Small children could feed the chickens. Girls by the age of 4 were put to sewing samplers. These small children could sow seeds, weed, walk behind the plow, gather eggs, pick fruits and veggies, gather wood for fuel, bring water from a well or stream, and start learning how to dip candles, bake, make ‘receipts’, etc.
A girl of 12 then had had about EIGHT YEARS of domestic training.
And while she may have married at 12, often in a move whereby either she brought some goods to her husband, or he brought some goods to her family, quite often after marriage she would remain in her home, or go to his parents, and be taught precisely what she would need to know in THAT locale, while he was off either getting training in his future job, making a ‘year of service’ to the overlord, serving in a battle or skirmish (if he died his wife, even if the marriage was not consummated, would have some kind of compensation for his death), etc.