Chimpanzees and humans have exactly the same layout of the brain. But surprisingly, human bipedal motion is performed by the neocortex in humans and not by chimps. Many human centric motor-control seems to have migrated to the neocortex.
Chimpanzees have faster reflexes and larger short term memories than humans. The effect of the particular configuration of the human brain led to inferior cognitive skills in some areas and stronger ones in another area.
There is a mistaken belief that human brains are across the board superior to other brains in cognitive capabilities. The truth is that evolution has made tradeoffs such that we've lost some skills to gain other skills. We are narrowly smarter because we are broadly dumber.
As technology evolves, we become broadly dumber. This is a consequence of human capability to outsource cognition to our tools. We are becoming smarter at being specialized and our environments are taking over our remaining general intelligence.
The story of human intelligence is one of an increase in private narrow intelligence and a commensurate increase in socialized general intelligence. The effect of specialization is the narrowing of empathy.
The popularity of zombie stories reflects our collective intuition about this. We intuit a growing increase in the 'zombies' around us. We see the growth of the growing masses of people devoid of empathy.
We are becoming the automaton that we had fears that our tools would become. We have become the tools. The biological eco-system of the planet as a consequence suffers from the zombies that we have become.
