Why is early development more critical than later development?

People develop in stages. The early years of 0-4 years old are the most important because that is when a child is learning to walk, talk, and think. There are more active brain cells in the first few years than any time a person's life. These are the years where the personality and values are set and where a child learns right from wrong. All behaviors that are learned are learned in the first 4 years. Around the age of 10 a child's brain begins reorganize and get rid of useless information to make room for new learning, but behavior stays the same. The teen years see the development of abstract and critical thinking as the person moves into puberty and into adulthood. Yet, the frontal part of the brain in the teen years is not quite developed and this is one reason that many teens do things that seem rather dangerous or thoughtless. As people move into adulthood the brain becomes fully developed by the time a person reaches the age of 25. Adults also go through stages in life, but who they were at 4 still stays with them. That is why the early years are so important.