When anthropologists study cultures like the Matsigenkas’, they tend to see patterns. The Matsigenka prize hard work and self-sufficiency. Their daily rituals, their child-rearing practices, and even their folktales reinforce these values, which have an obvious utility for subsistence farmers. Matsigenka stories often feature characters undone by laziness; kids who still don’t get the message are rubbed with an itch-inducing plant.

In contemporary American culture, the patterns are more elusive. What values do we convey by turning our homes into warehouses for dolls? By assigning our kids chores and then rewarding them when they screw up? By untying and then retying their shoes for them? It almost seems as if we’re actively trying to raise a nation of “adultescents.” And, perhaps without realizing it, we are.

As Melvin Konner, a psychiatrist and anthropologist at Emory University, points out in “The Evolution of Childhood” (Belknap), one of the defining characteristics of Homo sapiens is its “prolonged juvenile period.” Compared with other apes, humans are “altricial,” which is to say immature at birth. Chimpanzees, for instance, are born with brains half their adult size; the brains of human babies are only a third of their adult size. Chimps reach puberty shortly after they’re weaned; humans take another decade or so. No one knows when exactly in the process of hominid evolution juvenile development began to slow down, but even Homo ergaster, who evolved some 1.8 million years ago, seems to have enjoyed—if that’s the right word—a protracted childhood. It’s often argued by anthropologists that the drawn-out timetable is what made humans human in the first place. It’s the fact that we grow up slowly that makes acquiring language and building complicated social structures possible.

The same trend that appears in human prehistory shows up in history as well. The farther back you look, the faster kids grew up. In medieval Europe, children from seven on were initiated into adult work. Compulsory schooling, introduced in the nineteenth century, pushed back the age of maturity to sixteen or so. By the middle of the twentieth century, college graduation seemed, at least in this country, to be the new dividing line. Now, if Judd Apatow is to be trusted, it’s possible to close in on forty without coming of age.

Evolutionarily speaking, this added delay makes a certain amount of sense. In an increasingly complex and unstable world, it may be adaptive to put off maturity as long as possible. According to this way of thinking, staying forever young means always being ready for the next big thing (whatever that might be).

Or adultesence might be just the opposite: not evidence of progress but another sign of a generalized regression. Letting things slide is always the easiest thing to do, in parenting no less than in banking, public education, and environmental protection. A lack of discipline is apparent these days in just about every aspect of American society. Why this should be is a much larger question, one to ponder as we take out the garbage and tie our kids’ shoes. ♦