In 2004, Carolina Izquierdo, an anthropologist at the University of California, Los Angeles, spent several months with the Matsigenka, a tribe of about twelve thousand people who live in the Peruvian Amazon. The Matsigenka hunt for monkeys and parrots, grow yucca and bananas, and build houses that they roof with the leaves of a particular kind of palm tree, known as a kapashi. At one point, Izquierdo decided to accompany a local family on a leaf-gathering expedition down the Urubamba River.

It almost seems as if we’re trying to raise a nation of “adultescents.” Illustration by Christoph Abbrederis

A member of another family, Yanira, asked if she could come along. Izquierdo and the others spent five days on the river. Although Yanira had no clear role in the group, she quickly found ways to make herself useful. Twice a day, she swept the sand off the sleeping mats, and she helped stack the kapashi leaves for transport back to the village. In the evening, she fished for crustaceans, which she cleaned, boiled, and served to the others. Calm and self-possessed, Yanira “asked for nothing,” Izquierdo later recalled. The girl’s behavior made a strong impression on the anthropologist because at the time of the trip Yanira was just six years old.

While Izquierdo was doing field work among the Matsigenka, she was also involved in an anthropological study closer to home. A colleague of hers, Elinor Ochs, had recruited thirty-two middle-class families for a study of life in twenty-first-century Los Angeles. Ochs had arranged to have the families filmed as they ate, fought, made up, and did the dishes.

Izquierdo and Ochs shared an interest in many ethnographic issues, including child rearing. How did parents in different cultures train young people to assume adult responsibilities? In the case of the Angelenos, they mostly didn’t. In the L.A. families observed, no child routinely performed household chores without being instructed to. Often, the kids had to be begged to attempt the simplest tasks; often, they still refused. In one fairly typical encounter, a father asked his eight-year-old son five times to please go take a bath or a shower. After the fifth plea went unheeded, the father picked the boy up and carried him into the bathroom. A few minutes later, the kid, still unwashed, wandered into another room to play a video game.

In another representative encounter, an eight-year-old girl sat down at the dining table. Finding that no silverware had been laid out for her, she demanded, “How am I supposed to eat?” Although the girl clearly knew where the silverware was kept, her father got up to get it for her.

In a third episode captured on tape, a boy named Ben was supposed to leave the house with his parents. But he couldn’t get his feet into his sneakers, because the laces were tied. He handed one of the shoes to his father: “Untie it!” His father suggested that he ask nicely.

“Can you untie it?” Ben replied. After more back-and-forth, his father untied Ben’s sneakers. Ben put them on, then asked his father to retie them. “You tie your shoes and let’s go,’’ his father finally exploded. Ben was unfazed. “I’m just asking,’’ he said.

A few years ago, Izquierdo and Ochs wrote an article for Ethos, the journal of the Society of Psychological Anthropology, in which they described Yanira’s conduct during the trip down the river and Ben’s exchange with his dad. “Juxtaposition of these developmental stories begs for an account of responsibility in childhood,” they wrote. Why do Matsigenka children “help their families at home more than L.A. children?” And “Why do L.A. adult family members help their children at home more than do Matsigenka?” Though not phrased in exactly such terms, questions like these are being asked—silently, imploringly, despairingly—every single day by parents from Anchorage to Miami. Why, why, why?

With the exception of the imperial offspring of the Ming dynasty and the dauphins of pre-Revolutionary France, contemporary American kids may represent the most indulged young people in the history of the world. It’s not just that they’ve been given unprecedented amounts of stuff—clothes, toys, cameras, skis, computers, televisions, cell phones, PlayStations, iPods. (The market for Burberry Baby and other forms of kiddie “couture” has reportedly been growing by ten per cent a year.) They’ve also been granted unprecedented authority. “Parents want their kids’ approval, a reversal of the past ideal of children striving for their parents’ approval,” Jean Twenge and W. Keith Campbell, both professors of psychology, have written. In many middle-class families, children have one, two, sometimes three adults at their beck and call. This is a social experiment on a grand scale, and a growing number of adults fear that it isn’t working out so well: according to one poll, commissioned by Time and CNN, two-thirds of American parents think that their children are spoiled.

The notion that we may be raising a generation of kids who can’t, or at least won’t, tie their own shoes has given rise to a new genre of parenting books. Their titles tend to be either dolorous (“The Price of Privilege”) or downright hostile (“The Narcissism Epidemic,” “Mean Moms Rule,” “A Nation of Wimps”). The books are less how-to guides than how-not-to’s: how not to give in to your toddler, how not to intervene whenever your teen-ager looks bored, how not to spend two hundred thousand dollars on tuition only to find your twenty-something graduate back at home, drinking all your beer.

Not long ago, Sally Koslow, a former editor-in-chief of McCall’s, discovered herself in this last situation. After four years in college and two on the West Coast, her son Jed moved back to Manhattan and settled into his old room in the family’s apartment, together with thirty-four boxes of vinyl LPs. Unemployed, Jed liked to stay out late, sleep until noon, and wander around in his boxers. Koslow set out to try to understand why he and so many of his peers seemed stuck in what she regarded as permanent “adultescence.” She concluded that one of the reasons is the lousy economy. Another is parents like her.

“Our offspring have simply leveraged our braggadocio, good intentions, and overinvestment,” Koslow writes in her new book, “Slouching Toward Adulthood: Observations from the Not-So-Empty Nest” (Viking). They inhabit “a broad savannah of entitlement that we’ve watered, landscaped, and hired gardeners to maintain.” She recommends letting the grasslands revert to forest: “The best way for a lot of us to show our love would be to learn to un-mother and un-father.” One practical tip that she offers is to do nothing when your adult child finally decides to move out. In the process of schlepping Jed’s stuff to an apartment in Carroll Gardens, Koslow’s husband tore a tendon and ended up in emergency surgery.

Madeline Levine, a psychologist who lives outside San Francisco, specializes in treating young adults. In “Teach Your Children Well: Parenting for Authentic Success” (HarperCollins), she argues that we do too much for our kids because we overestimate our influence. “Never before have parents been so (mistakenly) convinced that their every move has a ripple effect into their child’s future success,” she writes. Paradoxically, Levine maintains, by working so hard to help our kids we end up holding them back.

“Most parents today were brought up in a culture that put a strong emphasis on being special,” she observes. “Being special takes hard work and can’t be trusted to children. Hence the exhausting cycle of constantly monitoring their work and performance, which in turn makes children feel less competent and confident, so that they need even more oversight.”

Pamela Druckerman, a former reporter for the Wall Street Journal, moved to Paris after losing her job. She married a British expatriate and not long after that gave birth to a daughter. Less out of conviction than inexperience, Druckerman began raising her daughter, nicknamed Bean, à l’Américaine. The result, as she recounts in “Bringing Up Bébé” (Penguin Press), was that Bean was invariably the most ill-behaved child in every Paris restaurant and park she visited. French children could sit calmly through a three-course meal; Bean was throwing food by the time the apéritifs arrived.

Druckerman talked to a lot of French mothers, all of them svelte and most apparently well rested. She learned that the French believe ignoring children is good for them. “French parents don’t worry that they’re going to damage their kids by frustrating them,” she writes. “To the contrary, they think their kids will be damaged if they can’t cope with frustration.” One mother, Martine, tells Druckerman that she always waited five minutes before picking up her infant daughter when she cried. While Druckerman and Martine are talking, in Martine’s suburban home, the daughter, now three, is baking cupcakes by herself. Bean is roughly the same age, “but it wouldn’t have occurred to me to let her do a complicated task like this all on her own,” Druckerman observes. “I’d be supervising, and she’d be resisting my supervision.”

Also key, Druckerman discovered, is just saying non. In contrast to American parents, French parents, when they say it, actually mean it. They “view learning to cope with ‘no’ as a crucial step in a child’s evolution,” Druckerman writes. “It forces them to understand that there are other people in the world, with needs as powerful as their own.”

Not long ago, in the hope that our sons might become a little more Matsigenka, my husband and I gave them a new job: unloading the grocery bags from the car. One evening when I came home from the store, it was raining. Carrying two or three bags, the youngest, Aaron, who is thirteen, tried to jump over a puddle. There was a loud crash. After I’d retrieved what food could be salvaged from a Molotov cocktail of broken glass and mango juice, I decided that Aaron needed another, more vigorous lesson in responsibility. Now, in addition to unloading groceries, he would also have the task of taking out the garbage. On one of his first forays, he neglected to close the lid on the pail tightly enough, and it attracted a bear. The next morning, as I was gathering up the used tissues, ant-filled raisin boxes, and slimy Saran Wrap scattered across the yard, I decided that I didn’t have time to let my kids help out around the house. (My husband informed me that I’d just been “kiddie-whipped.”)

Ochs and Izquierdo noted, in their paper on the differences between the family lives of the Matsigenka and the Angelenos, how early the Matsigenka begin encouraging their children to be useful. Toddlers routinely heat their own food over an open fire, they observed, while “three-year-olds frequently practice cutting wood and grass with machetes and knives.” Boys, when they are six or seven, start to accompany their fathers on fishing and hunting trips, and girls learn to help their mothers with the cooking. As a consequence, by the time they reach puberty Matsigenka kids have mastered most of the skills necessary for survival. Their competence encourages autonomy, which fosters further competence—a virtuous cycle that continues to adulthood.

The cycle in American households seems mostly to run in the opposite direction. So little is expected of kids that even adolescents may not know how to operate the many labor-saving devices their homes are filled with. Their incompetence begets exasperation, which results in still less being asked of them (which leaves them more time for video games). Referring to the Los Angeles families, Ochs and Izquierdo wrote, “Many parents remarked that it takes more effort to get children to collaborate than to do the tasks themselves.”

One way to interpret these contrary cycles is to infer that Americans have a lower opinion of their kids’ capacities. And, in a certain sense, this is probably true: how many parents in Park Slope or Brentwood would trust their three-year-olds to cut the grass with a machete? But in another sense, of course, it’s ridiculous. Contemporary American parents—particularly the upscale sort that “unparenting” books are aimed at—tend to take a highly expansive view of their kids’ abilities. Little Ben may not be able to tie his shoes, but that shouldn’t preclude his going to Brown.

In “A Nation of Wimps: The High Cost of Invasive Parenting” (Broadway), Hara Estroff Marano argues that college rankings are ultimately to blame for what ails the American family. Her argument runs more or less as follows: High-powered parents worry that the economic opportunities for their children are shrinking. They see a degree from a top-tier school as one of the few ways to give their kids a jump on the competition. In order to secure this advantage, they will do pretty much anything, which means not just taking care of all the cooking and cleaning but also helping their children with math homework, hiring them S.A.T. tutors, and, if necessary, suing their high school. Marano, an editor-at-large at Psychology Today, tells about a high school in Washington State that required students to write an eight-page paper and present a ten-minute oral report before graduating. When one senior got a failing grade on his project, his parents hired a lawyer.

Today’s parents are not just “helicopter parents,” a former school principal complains to Marano. “They are a jet-powered turbo attack model.” Other educators gripe about “snowplow parents,” who try to clear every obstacle from their children’s paths. The products of all this hovering, meanwhile, worry that they may not be able to manage college in the absence of household help. According to research conducted by sociologists at Boston College, today’s incoming freshmen are less likely to be concerned about the rigors of higher education than “about how they will handle the logistics of everyday life.”

One of the offshoots of the L.A. family study is a new book, “Life at Home in the Twenty-First Century” (Cotsen Institute of Archaeology), which its authors—the anthropologists Jeanne Arnold, of U.C.L.A., Anthony Graesch, of Connecticut College, and Elinor Ochs—describe as a “visual ethnography of middle-class American households.” Lavishly illustrated with photographs (by Enzo Ragazzini) of the families’ houses and yards, the book offers an intimate glimpse into the crap-strewn core of American culture.

“After a few short years,” the text notes, many families amass more objects “than their houses can hold.” The result is garages given over to old furniture and unused sports equipment, home offices given over to boxes of stuff that haven’t yet been stuck in the garage, and, in one particularly jam-packed house, a shower stall given over to storing dirty laundry.

Children, according to “Life at Home,” are disproportionate generators of clutter: “Each new child in a household leads to a 30 percent increase in a family’s inventory of possessions during the preschool years alone.” Many of the kids’ rooms pictured are so crowded with clothes and toys, so many of which have been tossed on the floor, that there is no path to the bed. (One little girl’s room contains, by the authors’ count, two hundred and forty-eight dolls, including a hundred and sixty-five Beanie Babies.) The kids’ possessions, not to mention their dioramas and their T-ball trophies, spill out into other rooms, giving the houses what the authors call “a very child-centered look.”

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.