Buckner and Krienen say this change occurred because of the way brains develop. In the human brain, some neurons still receive chemical signals that cause them to form a bucket brigade from the sensory cortices to the motor cortices. But because of the brain’s size, some neurons are too far from the signals to follow their commands.
“They may have broken off and formed a new circuit,” Buckner said.
This new wiring may have been crucial to the evolution of the human mind. Our association cortices liberate us from the rapid responses of other mammal brains. These new brain regions can communicate without any input from the outside world, discovering new insights about our environment and ourselves.
Sherwood, the George Washington University expert, praised the hypothesis for being “fairly frugal.” The emergence of the human mind might not have been a result of a vast number of mutations that altered the fine structure of the brain. Instead, a simple increase in the growth of neurons could have untethered them from their evolutionary anchors.
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