AT THE gates of Santa Monica College, in Los Angeles, a young man with a skateboard is hanging out near a group of people who are smoking marijuana in view of the campus police. His head is clouded, too—but with worry, not weed. He frets about his student loans and the difficulty of finding a job, even fearing that he might end up homeless. “Not to sound intense,” he adds, but robots are taking work from humans. He neither smokes nor drinks much. The stigma against such things is stronger than it was for his parents’ generation, he explains.

Young people are indeed behaving and thinking differently from previous cohorts at the same age. These shifts can be seen in almost every rich country, from America to the Netherlands to South Korea. Some have been under way for many years, but they have accelerated in the past few. Not all of them are benign.

Perhaps the most obvious change is that teenagers are getting drunk less often (see chart 1). They start drinking later: the average age at which young Australians first try alcohol has risen from 14.4 to 16.1 since 1998. And even when they start, they sip rather than chug. In Britain, where a fifth of 16- to 24-year-olds do not drink at all, the number of pubs is falling by about 1,000 a year, and nightclubs are faring even worse. In the past young people went out for a drink and perhaps had something to eat at the same time, says Kate Nicholls, head of the Association of Licensed Multiple Retailers, a trade group. Now it is the other way round.

Other drugs are also falling from favour. Surveys by the European Monitoring Centre for Drugs and Drug Addiction show that the proportion of 15- to 16-year-olds who have tried cigarettes has been falling since 1999. A rising proportion of teenagers have never tried anything mind-altering, including alcohol, tobacco, cannabis, inhalants and sedatives. The proportion of complete abstainers rose from 11% to 31% in Sweden between 2003 and 2015, and from 23% to an astounding 61% in Iceland. In America, all illicit drugs except marijuana (which is not illicit everywhere) have become less popular. Mercifully, the decline in teenage opioid use is especially steep.

Nor are young people harming each other as much as they used to. Fighting among 13- and 15-year-olds is down across Europe. Juvenile crime and anti-social behaviour have dropped in England and Wales, and with them the number of juvenile convicts. In 2007 almost 3,000 young people were in custody; by 2016 the number was below 1,000.

Teenagers are also having less sex, especially of the procreative kind. In 1991, 54% of American teenagers in grades nine to 12 (ages 14-18) reported that they were sexually experienced, and 19% claimed to have had sex with at least four partners. In 2015 those proportions were 41% and 12%. America’s teenage birth rate crashed by two-thirds during the same period. As with alcohol, the abstention from sex seems to be carrying through into early adulthood. Jean Twenge, a psychologist at San Diego State University in California, has shown that the proportion of Americans aged 20-24 who report having no sexual partner since the age of 18 rose from 6.3% for the cohort born in the late 1960s to 15.2% for those born in the early 1990s. Japan is a more extreme case. In 2015, 47% of unmarried 20- to 24-year-old Japanese men said they had never had sex with a woman, up from 34% in 2002.

In short, young people are less hedonistic and break fewer rules than in the past. They are “kind of boring”, says Shoko Yoneyama, an expert on Japanese teenagers at the University of Adelaide. What is going on?

They tuck you up

One possible explanation is that family life has changed. A study of 11 countries by Giulia Dotti Sani and Judith Treas, two academics, found that parents spend much more time on child care. In America, the average parent spent 88 minutes a day primarily looking after children in 2012—up from 41 minutes in 1965. Fathers have upped their child-care hours most in proportional terms, though they still do much less than mothers. Because families are smaller, the hours are spread across fewer offspring.

Those doted-upon children seem to have turned into amenable teenagers. In 28 out of 34 rich countries surveyed by the World Health Organisation, the proportion of 15-year-old boys who said they found it easy to talk to their fathers rose between 2001-02 and 2013-14. Girls found it easier to talk to their fathers in 29 out of 34 countries. The trend for mothers is similar but less strong. And even teenagers who do not talk to their parents seem to listen to them. Dutch surveys show that teenagers have come to feel more pressure from their parents not to drink. That is probably the main reason for the decline in youthful carousing since 2003.

Another possibility is that teenagers and young people are more focused on school and academic work. Across the OECD club of rich countries, the share of 25- to 34-year-olds with a tertiary degree rose from 26% to 43% between 2000 and 2016. A larger proportion of teenagers believe they will go on to university.

As a result, they may be staying at home more. Mike Roe, who runs a drop-in youth club in Brighton, in southern England, says that ten or 15 years ago clubs like his often used to stay open until 11pm on school nights. That is now regarded as too late. Oddly, though, teenagers are not necessarily filling their evenings with useful work. Between 2003 and 2012, the amount of time 15-year-olds spent doing homework fell by an hour a week across the OECD, to just under five hours.

Meanwhile paid work is collapsing. In 2016 just 43% of American 16- to 19-year-olds were working in July, during the summer holidays—down from 65% two decades earlier. The retreat from lifeguarding and burger-flipping worries some Americans, including Ben Sasse, a senator from Nebraska, who argues that boring paid work builds character and resilience. Teenagers are no fools, however. The average 16- to 19-year-old American worker earned $9.20 an hour in 2016. Though an improvement on previous years, that is a pittance next to the cost of university tuition or the large and growing wage differential between professional-level jobs and the rest. The fall in summer working has been mirrored by a rise in summer studying.

Ann Hagell, a British adolescent psychologist, suggests another explanation. Today’s young people in Western countries are increasingly ethnically diverse. Britain, for example, has received large flows of immigrants from Africa, south Asia and eastern Europe. Many of those immigrants arrive with strong taboos against drinking, premarital sex and smoking—at least among girls—and think that only paupers send their children out to work. Ms Hagell points out that teenage drinking is rarest in London, where immigrants cluster.

Finally, technology has probably changed people’s behaviour. Teenagers are heavy internet users, the more so as they acquire smartphones. By their own account, 15-year-olds in OECD countries spent 146 minutes a day online on weeknights in 2015, up from 105 minutes in 2012. Chileans lead the rich world, putting in an average of 195 minutes on weekdays and 230 minutes on weekend days.

Social media allow teenagers’ craving for contact with peers to be squared with parents’ desire to keep their offspring safe and away from harmful substances. In America, surveys known as Monitoring the Future have recorded a decline in unsupervised hanging-out, which has been especially sharp since 2012. Teenagers who communicate largely online can exchange gossip, insults and nude pictures, but not bodily fluids, blows, or bottles of vodka.

The digital trade-off comes at a cost. Sophie Wasson, a psychologist at Harvard-Westlake, a private high school in Los Angeles, says that some teenagers seem to use social media as an alternative to face-to-face communication. In doing so, they pass up some opportunities to develop deep emotional connections with their friends, which are built on non-verbal cues as well as verbal ones. Ms Wasson believes that social media widen the gap between how teenagers feel about themselves and what they think their friends want them to be. Online, everybody else is always happy, good-looking and at a party.

Technology also enhances surveillance. Parents track their children’s phones and text frequently to ask where they are. Benjamin Pollack, a student at the University of Pennsylvania, remembers attending a camp in Israel when he was in high school. He communicated with his mother every day, using Facebook Messenger and other tools. As it happens, his mother had attended the same camp when she was a teenager. She contacted her own mother twice in eight weeks.

Worries about teenagers texting and playing computer games too much (and, before that, watching too much television) have largely given way to worries about smartphones and social media. Last November Chamath Palihapitiya, formerly a Facebook executive, said that his children were “not allowed to use that shit”. But strong evidence that technology is rewiring teenagers’ minds is so far lacking. American and British data show that, although heavy internet use is associated with unhappiness, the correlation is weak. One paper on Britain by Andrew Przybylski and Netta Weinstein suggests that heavy computer and smartphone use lower adolescents’ mood much less than skipping breakfast or skimping on sleep.

Sufficient unto the day

Still, something is up. Whether it is a consequence of phones, intrusive parenting, an obsessive focus on future job prospects or something else entirely, teenagers seem lonelier than in the past. The OECD’s PISA surveys show that the share of 15-year-olds who say they make friends easily at school has dropped in almost every country (see chart 2). Some Western countries are beginning to look like Japan and South Korea, which struggle with a more extreme kind of social isolation in which young people become virtual hermits.