Creativity and the Aging Mind

It is a truism in the world of mathematics that the great mathematicians have done all their best work before the age of thirty. In other fields may be a bit later, but generally when you find revolutionary thinkers, their great work is done early in their career.

As someone who just turned 40, it's got me thinking. If this is true, why?

Seems like there are several possible explanations:

(1) Biology 1 (body focused) -- Great advances take incredible energy and stamina and this is something one has when younger, but loses as one gets older.

(2) Biology 2 (brain focused) -- There are biological changes within the aging brain that makes it less flexible and therefore less likely to display the creativity needed to make new advances.

(3) Advantageous Immaturity -- Great advances take minds uncluttered by a deep understanding of the accepted paradigm, understanding that comes with age and depth of study. Over time, we come to realize that things are not as clean cut as we first think. Progress comes from naively rejecting paths that have been fruitful in the past in favor of new paths that may or may not be. Sometimes these youthful sprints into the unknown lead to new and beautiful meadows, but as one ages, one matures and learns to appreciate what the different paths have to offer. Smelling the roses on the paths already traveled doesn't blaze new ones.

(4) Psychology -- We naturally resist change. When young, everything is new so progress along pathways not previously thought of is easy, but when older we do not want what is familiar and comfortable taken from us and this hampers intellectual advancement.

(5) Sociology -- When young, we have nothing but our work to tie us down, but as we get older, we accumulate commitments to family, to institutions, and to community. We are spread thinner and therefore cannot, indeed do not want to, give the work the undivided attention of our younger selves, undivided attention that is needed for advancement.

(6) Economics 1 -- When younger, we have little stake in the current best theory and every incentive to overthrow it. When older, our earlier successes are the key to recognition and come to define us professionally. Instead of trying to overthrow our earlier work, we try to extend it -- and thereby our status -- making it unlikely that we will willingly surrender what makes us important, the old work.

(7) Economics 2 -- As one gets older, one figures out how to play the game successfully and thereby becomes part of the ossified institution and entrenched in its reward structure. The motivation is thereby to protect the status quo since it is the source of one's status.

(8) Altruism -- Older thinkers see the new pathways perfectly well, but like parents hiding easter eggs, they pretend it was the Easter Bunny just to see the faces of the youngster when they discover them.

So, which of these if any are the operative factors? The main ones? Others?