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How did the human brain evolve?

QUESTION: The human brain is extremely complex. It is noted that we only use a portion of its capabilities. From an evolutionary standpoint, why and how would such a complex organ evolve? I would think evolution would produce a brain that is used to 70-90% of total capacity, yet ours are not. Is this an erroneous assumption? Is it a valid statement that when God created us, Adam was using much more of his brain than we are today?.

RESPONSE: I contacted a couple of professionals in biology to make sure I was on track with this one. Here is a quote from one of the responses: "The idea that we do not use all of our brain is a myth. There are not 'untapped powers' or anything of the sort. The idea is probably originated because in several degenerative conditions, greater than 90% of the neurons must be lost before there is a noticeable effect. It may also come from the fact that roughly 10% of the cells are neurons, the rest mostly glia. Different portions of the brain are used for different functions and there is some redundancy and some ability to transfer function following a stroke or other trauma." You may also be interested in information on this web page: http://www.dana.org/books/press/progressreport/update98.cfm#c. One of the things mentioned there is this: "What enables the brain to act as command center for the body and mind? The activities of 100 billion neurons are involved, each one forming connections with an average of 10 thousand others. Each neuron communicates with one or more others by sending a particular chemical messenger, called a neurotransmitter, across the gap that separates them.  "Some 50 neurotransmitters have been identified. These messengers are important in maintaining an ever-changing yet stable environment. When their balance is upset, many disorders can result. The interplay between neurotransmitters and the sites on nerve cells that recognize them forms the basis for many effective medications and therapies."
     In other words, we use all of our brains. The point then would not be how much brain we use, but how efficiently we use it and whether or not there has been damage either by heredity (mutations) or after birth which must be circumvented, as the brain does have redundancy ability in a number of areas so that the damaging of one portion need not permanently cripple in many instances.
     As an aside here, I have a profoundly retarded son (IQ measures about 19) who had encephalitis when he was three. And yet, even with that horrid amount of damage, it is very evident that the damage was localized. NO ONE sneaks better! This kid wants a cookie, and a cookie he will get! It's quite fascinating watching him manipulate what needs to be manipulated, and watch for the opportunity. Yet he cannot speak and will never be toilet trained. He cannot be taught to even sort two items. Still, at almost 15 years old, he is as full of personality as anyone else I know. The brain is truly an amazing organ. 
     One last note -- how did the brain evolve? It didn't. It was created.

     Helen Fryman

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