[gizmo686]

My guess would be it is, as you indicated, an evolutionary development. When humans are young, we have very little knowledge of how the world works, knowledge which will help our chances of survival later in life. We also have our parents providing what we need to survive (at least during our early childhood). It makes sense that at this time we try to learn as much about the world as possible.

As we grow up, we start to already know more about the world, so their is a diminishing return on more exploration. We also (becuase of our increased knowledge) would move to being the more productive members of the species, so it makes sense for our efforts to go more into survival so our offspring can devote their resources to exploration.