Neuroscience has opened many windows on the brain and the way it works and while there is ALOT more to learn, there is not evidence that we do not use all of our brainpower. Just because scientists do not know what activity (or lack thereof) in one part of the brain at one time means, it does not mean nothing is happening. A hundred to two hundred billion neurons, polarizing or depolarizing from a few times a second to once every second or so is a complex system to study.
“Smart” or “stupid” are outcomes in behavior due to genetics and environment. Some people are simply born with brain wiring that enables them to see connections between things or have better memory – abilities that often translate into “smart.” It doesn’t mean these people will be smart if they do not make it their business to learn and acquire information (e.g., school). On the other hand, some people are just born with less capacity to remember information and connect the dots, so to speak. The lack of these skills often translates to not-so-smart. There is a normal distribution of intelligence (no matter how you define it) in the human population. At one extreme end of the curve there is genius and at the other end, “stupid” idiots but thmost people are in the middle. However, genetics does not define everything, it only puts some limits on how far we can go if we choose to do so. “Average” people (let’s skip people who are genetically endowed morons or idiots) who work and study hard will be “smarter” than someone who does not put in the time. The same is true of people who are born “gifted” but for whatever reason, do not apply themselves. It’s all about maximizing your potential within whatever genetic range you are born with, so to some extent, there is choice. However, genetic predisposition to intelligence will limit how far hard work will take you and all the good genetic coding in the world will not help you if you do nothing. With the exception of an Einstein or a Michaelangelo or a Newton or Hawkings — people of truly extraordinary genius- most people whether they are “smart” or “stupid” have to choose whether they want to achieve their potential. “Smart” people may have to work less and