Teens are becoming adults later than they used to

Teens are growing up more slowly than they did two decades ago, and today's 18-year-olds act like the 15-year-olds of the 1990s, per a new study. Researchers found that U.S. teens are engaging in adult activities — drinking, driving, dating and working for pay — later than they used to, delaying the transition from adolescence into adulthood.

The big picture: Avoid falling into the trap of seeing these trends as all good or all bad. "It's a tradeoff," lead researcher and author of a new book, iGen, Jean Twenge tells Axios. Today's teens may be less prepared for adulthood, but they're safer, with rates of car accidents and teen pregnancies falling dramatically.

The takeaways:

• 66% of 12th graders surveyed in 2014 had tried alcohol, compared to 81% in 1994
• 73% of them had drivers' licenses, down from 85% 20 years prior
• 58% went on dates, compared to 83% of 12th graders in 1994
• 56% worked for pay, down from 72% in 1994

The prevalence of risky behaviors has also declined, says Jeffrey Arnett, a professor of psychology whose work is cited in the study. Rates of binge-drinking, teen pregnancy and teen crime are lower than ever.

Yes, but: The transition into adulthood has slowed down so much that Arnett says people age 18 to 29 are living through a new life stage between adolescence and adulthood: "emerging adulthood." The consequences of this are that teens are less prepared for college and the workplace, Twenge says. "What really strikes me is that 'adulting' is now a verb," she says. "What's the alternative? Are you gonna go back to being a child?"

Be smart: Some of these behavioral changes can be attributed to technology, specifically the rise of the smartphone, Twenge recently wrote in the Atlantic. Teens are spending less time out getting into trouble and more time at home on their phones. But delaying adulthood also has to do with the fact that people live longer than they used to and more people expect to go to college instead of directly entering the workforce.

Twenge's Atlantic piece also claimed that heavy smartphone use has an adverse effect on teen mental health. But to say smartphones are destroying a generation is alarmist, tech writer and researcher Alexandra Samuel wrote in JSTOR in response. Data shows that "high school students who use social media a lot aren't any more depressed than those who use it a little," she wrote.

But Twenge is right to say technology is quickly widening generational gaps, Samuel tells Axios. "The pace of change is so rapid now that we raise our children in a world completely different from the one we grew up in," she says.

What's next: As technology advances, these trends could accelerate, Twenge says. "Soon 18-year-olds could look like the 13-year-olds" of the past.