Below is an interesting passage from Jill Lepore's article, "Baby Talk," which appeared in the books review section of the June 29 issue of The New Yorker. (The whole article is here.) I especially love its first sentence:
"Adolescence is a useful contrivance, midlife is a moving target, senior citizens are an interest group, and tweenhood is just plain made up. Parenthood seems, at first, different. There have always been parents, and parents have always been besotted with their children, awestruck by their impossible beauty, dopey high jinks, and strange little minds. But 'parenthood,' the word, dates only to the middle of the nineteenth century, and the notion that parenthood is a distinct stage of life, shared by men and women, is historically in its infancy. An ordinary life used to look something like this: born into a growing family, you help rear your siblings, have the first of your own half-dozen or even dozen children soon after you’re grown, and die before your youngest has left home. In the early eighteen-hundreds, the fertility rate among American women was between seven and eight children; adults couldn’t expect to live past sixty. To be an adult was to be a parent—nearly everyone lived in households with children—except that people didn’t usually think of themselves as “parents”; they were mothers or fathers, and everyone knew that there was a world of difference between the two."