I have read that human babies are born with far more inner connections between parts of their brains than will get used. I guess you can think of the ones for making Russian speech sounds as those that are likely to get pruned away for a child who grows up in an English-speaking environment. The brain experts say "Use it or lose it" and they mean that pathways and connections that aren't used get pruned off. Somebody said that it is Nature's way to over-do at first and then cut back.
This same phenomenon is in thinking and in learning. We want to understand a process. Especially in complicated research, we work down a tree of decisions. Each possible idea, often in several subsequent versions and modifications, gets explored. Over time, we learn which routes are not good ones and can often drop them from consideration. Once we know the way to Grandmother's house, we don't need to consider every possible side street and alternate pathway.
The model above is much simpler than many real-life decision and learning tasks. We generally think of time proceeding from left to right but with the right time and the right situation, we may be quite different people at later decision points than we were at the start. Further, external conditions can change: we may run low on water, find that an enemy is advancing on us or learn of a new invention for accomplishing something. The book "What Hath God Wrought" by Howe emphasizes that Americans in the early 1800's had a tough time believing that the newly invented telegraph and the expanding railroad system could send information and move people and goods to the new extent suddenly possible.
--
