It is fascinating to note that the changes occurred in the white matter portion of the brain. The general thought (challenged recently) is that only the gray/grey matter neurons 'mattered'. White matter was just conduction between the grey matter neurons (which had all the intelligence). The final quantity of these grey neurons was fixed shortly after birth and people kept losing them as they aged.

If it turns out the body can recruit white matter in learning then suddenly we have 10-50 times more cells (white matter/grey matter ratio) that can participate in intelligence. I suspect the way intelligence is organized would also differ between the white and grey regions. Not to mention how they interact with each other!. It calls into question a lot of the assumptions computational scientists make in coming up with the complexity of a simulated brain. We might be at the start of understanding how truly complex the brain is.

A good overview of this understudied portion of the brain is the the book "the other brain" by douglas fields.

http://www.amazon.com/The-Other-Brain-Breakthroughs-Revoluti...