Oh Grow Up!
Adulthood
When are you a grownup? We always think we are grown up; then we look back at our younger selves and think oh, no, we weren't grown up at all. The more practical historical question is: what are the documentable signs of adulthood?
Modern Markers
We have many. The age of eighteen is one because at that age we can vote, entering into citizenship, and we can serve in the military: we can kill and be killed. It's also, in most states, the age at which we can marry without parental consent.
There are other markers, though. For example, in some states you must be twenty-one to buy liquor. The entertainment business marks adulthood not at eighteen but at seventeen. Then there's the insurance industry, which doesn't lower your rates on auto insurance until age twenty-five. Finally, the country itself says you are not fitted to be a president until age thirty-five.
What did medieval society and law have to say?
One source are literary works, for age was a subject often addressed by poets and others. Dante said twenty-five, agreeing with the ancient Romans, but Petrarch said forty. Forty!
Full emancipation in Florence was twenty-five. In London apprenticeship could last until twenty-six. Any number of public offices were reserved to men of somewhat older age, usually in the thirties. But there were a number of scandalous cases of archbishops and cardinals being created as young as age twelve. In these cases, political ambition overrode societal norms.
Military service was somewhere around sixteen, though this was highly variable by place and time. Twelve was the Church's age for marriage for girls, fourteen for boys. Among peasants the age of majority was typically around twenty or twenty-one.
In Halesowen, England, peasant girls typically married between ages eighteen and twenty-two. Shepherd boys got their own flocks at fourteen. In general, you weren't a man or woman until you were married, and adult singles were universally regarded with some skepticism and suspicion.
One writer says adolescence is marked by music, drink, mock fights and wild companions. Adulthood is marked by pride, anger, gluttony and lechery. The writer was obviously speaking of males.
Becoming a knight didn't mean you'd reached adulthood, for the title could be and was bestowed on children. Nor becoming a priest make you an adult, nor getting your own land. Marriage was a key milestone.
This was perhaps more marked for women, because they changed households. Marriage meant the woman became mistress of her own household. Full adulthood, though, came with childbirth, for once she had children to raise no one could dispute that she was grown up.
In cities, appearing on the tax rolls meant you were a citizen and could vote. Age twenty-five in Florence, but in Augsburg not until you entered a guild. You couldn't enter a guild until you were married: no wife, no mastership and no citizenship.
Monks and friars, less so priests, were a social danger because they were adult males with no wife and no land. There was nothing to make them responsible.