“We walk through another part of the building. While we wait for an elevator, Dr. Kenyon unfolds a dinner-size napkin and holds it up in the air in front of his forehead. “This is about the size of your brain, spread out,” he says. “The part that matters. The cerebral cortex.” The 100 billion neurons there are also known as the brain’s gray matter. “And the human brain does things beyond anyone’s comprehension. Evolution created the smartest machine in this world.”