https://www.theatlantic.com/health/archive/2014/02/big-break...
It's always struck me as funny when people say 25 is when you're fully mature. After this point, you start to experience declines in ability. It's not maturity; it's the moment you start dying.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4906299/
You weren't an idiot as a teenager. You were just uneducated and inexperienced.
Personally, my decaying mental performance over the years is almost palpable. I feel like I am half-dead now compared to who I was 20 years ago. Sure I was nuts due to the powerful emotions, but that just means I was alive, not a talking corpse that I am now.
Brain morphology is irrelevant. "Development" might just mean aging. Measurable performance is all that matters.
It's analogous to athletics. Sure, you can have a talent for running. But you're not going to win races unless you train.
A mind is plastic, adaptable, and hence can be trained.
None of it is worth paying attention to.
I strongly disagree with this. I don't know if it is genuinely true in a biological sense, but in my life experience it is not even close to true. There are lots of things I do that are so far beyond my abilities as a teenager. It could be due to other factors, but my gut suggests those other factors are much more important than this comment about mere brain power leads us to believe.