What's to come is still unsure:
In delay there lies no plenty;
Then come kiss me, sweet and twenty,
Youth's a stuff will not endure.
The Times today has a long article on "emerging adulthood" (the tweens), increasingly advocated as a newly normative stage of psychological development. It is the ever more de rigueur period in which twenty-somethings "find themselves," bouncing in and out of jobs and relationships, moving back home, etc. It struck me because of the similarities with "new" psychopathological syndromes, such as increasingly mainstream obesity, (adult) ADHD, soft bipolarity, etc.
One similarity is the jostling of neuroscientific and cultural explanations. On the one hand, brain scans suggest that the pre-frontal cortex continues to develop until age 25, so why shouldn't we expect emotional and cognitive development to be an adventure until that time? Well, there is the fact that throughout much of the world and throughout history, sociological maturity kicked in well before age 25, that is, "emerging adulthood" is a phase that many have apparently been able to skip when needed.
The piece suggests that "emerging adulthood" may actually be an artifact of prosperity; basically, twenty-somethings lollygag around because they can, because they live in the most well-off nation-state in the history of the world, and their parents are willing and able to indulge them. To be sure, this is a mixed blessing: too much promise and too many choices can be burdensome. As I have argued before, the vices of the rich are now the vices of the middle class, who are rich beyond the dreams of avarice compared with most human beings who have ever lived. And yet we try to use neurobiology to justify this sociological state of affairs. It is the brain that adapts to the environment and to society, not vice versa.
And yet this needn't be a pejorative development. Life span is increasing, reproductive technologies augment the opportunities for child-bearing, and the retirement age may eventually be 70 or 75, so what is the hurry, exactly, to settle into the grind of work and children? The crucial change is in attitudes and expectations--the stigma of living with one's parents until age 30 is not so biting. Some sort of cultural tipping point has occurred, which may or may not have anything at all to do with neurobiology. This is allegedly about normal psychology, but it parallels metamorphoses in psychiatric diagnosis. We collectively decide what is normal, then look to science to try to justify the decision.