The head is very big, big enough to have a brain. A surgeon can have spare brains in stock. When a customer wants to buy a head, he asks, will that be low level or high-level brain. High? Ok. He removes top of the head, pulls out the two covering panels on both sides, and slides in high-level brain. God does not have to manufacture a brain, just the head. Don't like the feel of that one? Ok. Try this premium brain instead.