Jane C. HU reported for Slate Magazine on Nov 27, 2022:
“When Leonardo DiCaprio’s relationship with model/actress Camila Morrone ended three months after she celebrated her 25th birthday, the lifestyle site YourTango turned to neuroscience. DiCaprio has a well-documented history of dating women under 25. (His current flame, who is 27, is a rare exception.) “Given that DiCaprio’s cut-off point is exactly around the time that neuroscientists say our brains are finished developing, there is certainly a case to be made that a desire to date younger partners comes from a desire to have control,” the article said. It quotes a couples therapist, who says that at 25, people’s “brains are fully formed and that presents a more elevated and conscious level of connection”—the type of connection, YourTango suggests, that DiCaprio wants to avoid.
YourTango was parroting a factoid that’s gained a chokehold over pop science in the past decade: that 25 marks the age at which our brains become “fully developed” or “mature.” This assertion has been used as an explanation for a vast range of phenomena. After 25, it’s harder to learn, a Fast Company piece claimed. Because “the risk management and long-term planning abilities of the human brain do not kick into high gear” until 25, an op-ed in Mint argued, people shouldn’t get married before then. In early 2020, Slate’s sex columnists Jessica Stoya and Rich Juzwiak fielded a reader question about the ethics of having sex with people under 25. “I am told, at least once every couple weeks, that if you’re under 25, you’re incapable of consent because your ‘frontal lobes are still developing,’ ” the distressed reader wrote.
Even some young people now regard age 25 as a turning point with seemingly magical properties. In one Reddit thread, a 24-year-old asks whether older, presumably wiser Redditors noticed changes after 25. (“I suddenly stopped finding Leonardo DiCaprio attractive,” one commenter quipped.) Others use the factoid to justify a range of bad decisions, from why college kids continued hosting keggers at the height of COVID to why some men are terrible at texting…
…to add an air of credibility to its DiCaprio theory, YourTango excerpts a passage from a 2012 New York Times op-ed written by the psychologist Larry Steinberg, a giant in the field of adolescent development, well known for his four decades of research on adolescent and young adults. The passage YourTango quoted accurately describes the science, but it’s definitely a stretch to imply that it explains Leonardo DiCaprio’s dating history. When we spoke, I told Steinberg his work had been referenced in this way. “Oh no,” he said, laughing…
…Kate Mills, a developmental neuroscientist at the University of Oregon, was equally puzzled. “This is funny to me—I don’t know why 25,” Mills said. “We’re still not there with research to really say the brain is mature at 25, because we still don’t have a good indication of what maturity even looks like.”…
…The choices researchers make in their methodology and data analysis affect their results. Even the participants researchers study biases their data set. (It’s well established that most research is biased toward people in “WEIRD”—Western, educated, industrialized, rich, and democratic—countries.) Plus, the researchers said, “the cognitive or behavioral implications of a given brain image or pattern of activation are not necessarily straightforward.”
In other words, researchers might be able to take a picture or video of the brain, but it’s not always clear what this really shows. The interpretation of neuroimaging is the most difficult and contentious part; in a 2020 study, 70 different research teams analyzed the same data set and came away with wildly different conclusions. Now that tens of thousands of fMRI studies have been published, researchers are identifying flaws in common neuroscience methods and questioning the reliability of their measures.
That’s not to say we should disregard the neuroscience—we just need to acknowledge its limitations. “We are giving neuroscience a starring role where it should have a supporting role,” Steinberg said.
The hard work of defining what maturity or adulthood really is falls on us as a society. How we talk about maturity and adulthood—and the evidence we use to support that—has real-world consequences for our behavior and self-concept. It’s impossible to measure the full effect of the “maturity at 25” factoid, but the fact that some poor 24-year-old Redditor believes that something magical might happen to her in the coming year could very well affect how they think about themselves and what they’re capable of. Mills told me she’s heard from middle and high school students that their teachers often point to “brain science” as justification for their bad decisions. (Mills is currently working on a study to interview young people about what they think and feel when they hear those kinds of assertions.)
Even with a flimsy basis at best, the real-world consequences of the “brains are fully mature at 25” myth are only beginning to emerge. Some of those are relatively harmless; using this half-truth to explain Leonardo DiCaprio’s dating habits primarily hurts DiCaprio, who hardly needs our sympathy. But as people continue to cite this factoid, it has the power to create serious societal change. In some cases, the result might literally save lives—for instance, keeping dangerous weapons out of the hands of young people or preventing instances of capital punishment. In other cases, it could cost lives; anti-trans activists cite this as evidence that young people should not be allowed to access lifesaving, gender-affirming care. The ultimate trajectory of this growing belief—and the profound effect it could have on young lives—is impossible to know, but it’s clear that neuroscience has and will be deployed to shape policy.
Perhaps the whole enterprise needs a reframe. It’s unrealistic to expect people to appreciate all the nuances of neuroscience, and naive to believe that scientific evidence won’t be weaponized for political purposes. It feels inevitable that people will gravitate toward a neat, simple story that feels intuitively true: We’re adults at 25. But rather than using that factoid to defend bad decisions, why not use its lessons to reframe youth as an opportunity? As the brain develops in adolescence and early adulthood, it stays open to change; that’s what allows us to learn. “Children and adolescents are not broken adults, but rather, they’re functioning perfectly well for their developmental period,” Mills said. They’re exactly where they need to be; the extra malleability in youth prepares us to figure out our surroundings. “This is the time we’re learning about our identity, other people, how we fit into the world—we need the brain to be malleable,” she said. And while adolescence is typically a time of big changes, reaching adulthood doesn’t mean the end of that growth. You can make good or bad decisions at any age; you’ll mature and regress throughout your life. You, like your brain, are endlessly complex, and we’re so much more than brain scans will ever reveal.”
Julia Upton 