I question the correlation and causality. I wonder how much of these eras are caused by brain physiology and genetics versus changes in the behavior with age, which can even be caused by external sociological factors, for example. Or a mix of both.

> From 32 years, the brain architecture appears to stabilise compared with previous phases, corresponding with a “plateau in intelligence and personality”.

For example, here - is this *caused* by genetics, or is it because in today's society this is about the age when you have finished your schooling and first working experiences and have simply less to learn?

I know my examples simplify the reasoning, but the question about causality still stands, I think.