Why is our brain one instead of two?

Answer 1

Well, your brain is divided into 2 parts. The left side is for language and logic- such as math, reading, history, spanish, you get the point. The Right side is for creativity such as art, and music. Why it's divided into 2 parts, I am not sure. maybe so you can think about more at once because each side of the brain has it's own jobs.

Answer 2

Our brain is neither one or two, it is many.

The brain is composed of several nested brains starting at the top of the spinal cord: the fish brain, the amphibian brain, the reptile brain, the mammal brain, the primate brain. Each of these brains wraps around the one "beneath" it like Russian Nesting Dolls. The brain is also divided into two hemispheres. Only the primate brain produces what we call consciousness in us humans.

Each of these brains operates completely independently of all the other brains, doing the things it is responsible for. Adjacent brains however are interconnected and do intercommunicate, but often it seems not very well. The combined operation of all these brains creates our experiences and the illusion of having one brain, but it is only an illusion. Lab experiments easily demonstrate the fact that we have many independently operating loosely interconnected brains that sometimes have highly conflicting goals and intentions.