The development of brain neurons is not simply a matter of having more being better.
In fact, the "maturation" of the neural system is a process of "subtraction."
The brain's primitive state is an original network where all nodes have the same weight. As people carry out their daily activities, some neural connection pathways are used frequently, while others are not.
As such, the "frequently used" pathways gain a higher weight. The rarely used ones have a lower weight.
Then, the high-weight pathways are further reinforced and may even develop specialized "protective sheaths," forming mature "circuits" that become fixed in place.
The less frequently used pathways regress.
The neural connection pathways are effectively "specialized."
During this process, humans learn to walk, use their hands, talk...
This is also why people who don't talk for a long time turn into "mutes"—the pathways responsible for "speaking" have withered away, and they forget how to speak.
