It is amazing that the average person assigns adult intelligence based on a person's title or job. Scientists, doctors and lawyers top the list. Janitors and day laborers are seen as unintelligent, or they would have gone to school to be something better. There has to be something wrong with a smart person who does a less intelligent person's job: drugs, mental illness, or alcohol abuse are the usual suspects.
There are so many measures of intelligence these days, beginning with prenatal tests for Downs and other genetic disorders. Then, there are measures of neonatal abilities. The pugilistic response, walking, and reacting to sound are tested. As we develop, we exhibit abilities that may appear alarming, delayed, or abnormal to anxious new parents, but are actually, quite fine. If we are the last of a lot of children, no one worries unless we do not get with the program in a timely fashion.
There are measures of intelligence that are so refined that a person can be dissuaded from choosing the wrong career field. "Average" scores in tests for spatial recognition are not good indicators that a person should go into fields of architecture or map making. "Below average" scores in tests for reading comprehension do not encourage a legal career.
But are those scores "above average", "average" or "below average" because of training, mental focus on limited activities,or because of innate ability? Many times, people are tested when they have not studied or used a lot of math for years. Some people just never chose to be avid readers and writers, until they got computers and started with the Internets.
It would be interesting to see if intelligence tests showed a difference, when administered before the individual refreshes their basic education for a couple of weeks, then after they refresh their education for a couple of weeks.
Some individuals are far too focused on parts of their intellect, often to the severe detriment of the other important parts of their intellect. Doctors who just cannot relate to their patients or to lay persons as human beings are examples of individuals who are forced to focus in almost superhuman ways on a narrow and detailed field of study, to the detriment of other areas. The levels of gullibility, inability to deal with the world, and even stupidity can be astounding in scientists and mathematicians.
A relatively uneducated, but highly intelligent person can be broadly knowledgable, based on their ability to read, to retain facts that they have heard, and to apply what they hear or learn to the real world. Self taught street poets can build a complex, multi-platinum recording industry. And the most intelligent people in the world will not ever "get" it. A self taught hip hop dancer can detect a step that is a few millimeters off point or off beat. Music and dance that can be learned, but which cannot be taught is the basis of a multi billion dollar industry. All of it came from the minds of "worthless" street kids.
Intelligence is innate, but can only develop into something meaningful through learning, training, and application in the real world. It is a grave, grave mistake to discount some learning as "unimportant" and some applications as "worthless". They are not unimportant or worthless to the individuals who take what is available to them and apply their intellects and passion to inventing, to the arts, to mathematics, and to the sciences in ways that change the world.