When I was in my early twenties I was fascinated by a book called Getting from Twenty to Thirty: Surviving Your First Decade in the Real World by Mike Edelhart. It was published in 1983; I found it in the library. The main thesis of the book was that if you didn’t get started in a career and settled into a monogamous relationship by 30, chances are you never would. Gulp!
I now relate to the “emerging adult” concept http://www.nytimes.com/2010/08/22/magazine/22Adulthood-t.html?pagewanted=all
My twenties did look much more like this:
One-third of people in their 20s move to a new residence every year. Forty percent move back home with their parents at least once. They go through an average of seven jobs in their 20s, more job changes than in any other stretch. Two-thirds spend at least some time living with a romantic partner without being married.
It’s interesting that brain development continues to age 25, as I had friends who were married by then. That was definitely too early for me!
This former definition of adulthood, from the same article, reminds me of Olivia’s recent question as to whether childless women are real adults (http://readinginthebath.com/2012/05/07/not-a-real-adult/):
We’re in the thick of what one sociologist calls “the changing timetable for adulthood.” Sociologists traditionally define the “transition to adulthood” as marked by five milestones: completing school, leaving home, becoming financially independent, marrying and having a child. In 1960, 77 percent of women and 65 percent of men had, by the time they reached 30, passed all five milestones. Among 30-year-olds in 2000, according to data from the United States Census Bureau, fewer than half of the women and one-third of the men had done so.