The human brain is large and in charge, controlling everything you do—breathing, eating, moving, thinking, and even reading this sentence. Everything.
Humans have the largest brain for their body size in the animal world. Our closest relatives, chimpanzees, cannot perform tasks beyond those of an average toddler. What makes us so smart?
Whatever it is, it’s not in the brain stem. This part of the brain controls sleeping, heartbeat, and other basic, life-or-death activities. The human brain stem is very much like the brain stems of reptiles, birds, and other mammals. That makes sense, because the same fundamental, life-or-death activities happen in all animals’ bodies.
It’s not in the cerebellum (ser-i-BELL-um), which controls movement. Reptiles, birds, and mammals (including us) all move, so we have similar cerebellums. But other animals use most of their brainpower for moving, sensing, and surviving, because, as far as we know, they have relatively little brainpower left for thinking.
