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The myth that the human uses just 10% of his brain has been widely spread among people for around a century ago. And it is still very popular, considering that 2/3 of the public believes it is true. And what is stranger, roughly a half of the scientists believe so.How everything started? The myth occurred at the end of 19th century when William James, widely respected philosopher and psychologist stated: “Most of us do not meet our mental potential”. If you wonder who William James is and why his opinion had such weight, this is a man considered by some people to be the “Father of the American psychology”. He is also considered to be one of the founders of the functional psychology. His works covered various subjects such as education, psychology, metaphysics, religion and epistemology (also known as “theory of knowledge”). He was also the first man in USA to offer psychology courses.This is yet another proof why influential and famous people should be careful of what they say. William James was probably misunderstood and this misunderstanding was reinforced by the fact that the function of our frontal lobes and parietal areas remained undiscovered for a long time ago. Also damage applied to these areas didn’t cause any motor, sensor or other malfunctions, which was interpreted as “these parts are non-functional”. These brain parts were called “silent areas” for decades. Later researches proved that frontal lobes and parietal areas regulate our executive and integrative abilities. They are essential for our decision making process, adaptability to various circumstances every day, planning and reasoning abilities.Richard Cytowic, an American neurologist and author, busted the myth of the “10% brain usage” by making a simple calculation. He calculated how the human brain uses energy and compared it to other species. For example, the brain of an average dog consumes 5% of the total body energy and monkey brain consumes around 10% of the total energy. The human brain is just 2% of the body mass, but consumes approximately 20% of the daily amount of energy in an adult. In infants this percent is 60, in children it decreases to 50%. This is because the human brain packs more neurons than any other current species. There is a trend concerning body mass and number of neurons, which shows that species with bigger body mass have lower brain size. A 25 kilogram ape has around 53 milliard neurons inside its brain, for comparison the human brain is comprised of 86 milliard neurons.It is obvious that keeping all these neurons active at the same time will be energy inefficient. This is why the evolution has developed something called by science “sparse coding”. It means that relatively small proportion of brain is able to emit signals at any time. This type of signaling is effective because a small amount of signals has literally thousands of possible paths by which to distribute themselves. It is estimated that between 1% and 16% of the neurons should be active at any moment to maintain proper brain functioning.The evolution has proved that she’s cutting away what is useless, so if 90% of our brains were intact the evolution would have cut them thousands of years ago.