Once upon a time, humans were little more than monkeys. We had a smaller skull than we do now, and it primarily consisted of the limbic brain. That’s the deep, emotional, intuitive part of the brain—surrounded by a slim sliver of the outer cortex.
Over time, our digestive tract shrank as our outer cortex grew, becoming as dense as the limbic brain. The growth of this rational part of the brain brought about articulated speech and the ability to predict and plan for the future.
