So .. the thing is, this is a descriptive account of the biology of the brain. However, I sometimes see the "discourse machine" building narratives around pushing the age of majority later, and I suspect this will get used in ammunition for normative purposes.

Anecdotally I’ve felt this shift over the past few years. I am 33 and have always been a huge proponent of personal growth, change, pushing yourself to be better. In the past few years Ive felt the opposite urge, an urge to accept myself, flaws and all, as the hand I’ve been dealt and I must merely play that hand, not focus so much on what-ifs, etc. Perhaps this is my brain solidifying.

As the authors mentioned, ~30 years is the age many people have kids, and it is already well known that female brain changes after giving birth, for example. The authors didn't research if being a parent can explain a part of the difference (and also if parent brains are any different than childless people brains).

I'm personally curious about this: I'm slightly above 30, I observed significant changes in my behavior recently... and I became a parent this year.

Fascinating study.

The stats warrant some caution, though. The main finding is based on figure 4 [1] and I wouldn't be surprised if the number and location of these 'eras' varied a lot if the authors use 40,000 people instead of 4,000.

[1] https://www.nature.com/articles/s41467-025-65974-8/figures/4

I've always thought that I'm just extremely late to mature. I'm 36 now and haven't really felt like I sort of "get" things until my early 30s. My 20s were full of learning experiences, failures, and addiction to doing whatever the hell I wanted. I got a puppy with my wife at 29 and it felt like my life was over. This all really makes a lot of sense to me. It also makes me wonder why the human body rewards young parents when their brains are just simply not fully finished cooking. I couldn't have imagined raising a child at 22 with the way I acted and how important freedom was to me. I would've simply been a miserable father.

I do have felt similar shift around that age, but I wonder if it is due to reaching certain points in career where you are put into more leading position and have more confidence in what you do even if you don't have children? Easy to go into horoscope style confirmation bias here though.

Nonetheless I am never going to stop saying I still feel like I am 16. Just more confident 16.

It took me until my mid-30s to feel like I had crossed a threshold in processing grief and trauma from my late teen years. I was capable of adult behavior long before then, but my concept of the world and how I fit into it (or don't) was still childlike in many ways on a fundamental level.

Like most such things, I'd expect this to be a spectrum, and I may be somewhat of a late bloomer. Regardless, I have a theory that there is somewhat of a protective effect operating here. Believing in a simpler reality which involved future wish fulfillment for me - however unrealistic it was - may have helped me survive. Coming to acceptance of what I see as a more accurate but far bleaker perspective required me to grow strong enough to sustain my will to live despite that perspective.

Biggest lesson learned: I could not do it without at least one other person (or more) who I trust almost 100% with all of myself. Realizing that going it alone is futile is definitely part of what I consider becoming an adult, and it can take a long time to fully accept that.

Just the headline gels with my experience at age 54.

Wasn't it 25 that the prefrontal cortex matured and people could be considered adults? We will have to infantilize people until their 30s now?

The problem with such reports (the studies themselves method-wise etc are in general fine I guess, but how the results are interpreted and disseminated is the issue) is that unless we find some specific correlations with behavioural and such measures, it makes no sense to give these kind of meanings such as "adolescence", adult mode", behavioural/mental/cognitive matureness or whatever cultural or other norms one may think a "mature/adult person" should abide to. Especially since these abstract topological measures, while interesting, are not that trivially linked with real outcomes in a causal sense, and instead of eg simply reflecting rather environmental or other changes in a person's life.

I am personally supportive of any research that continues to define my age as having just achieved adulthood.

So you aren't an adult until your early 30's and you are an old slow guy not worth interviewing less than 10 years later.

Yeah I could distinctly feel my brain shifting into its adult era over the last couple of years (I'm 31)

It was kind of odd. I'm more serious now (but at the same time.. less?). I'm way more easily able to focus on what actually matters in this life. (In saying that, I think it's more likely that my brain has finally decided what's important... in a way I feel like a passenger)

This is interesting and alarming to me because judging by the changes in my life I appear to have entered the age-66 phase more than a decade and a half early despite remaining intellectually curious and physically fit enough.

In the last year or so I have begun to adjust my life expectations. My father was in his nineties when he died, but I no longer believe I will reach my seventies.

Things like this only tend to confirm my sense that I am neurologically ageing at a rate that is unusual.