How do you know when you have to go to the bathroom?<quoted text>
The three brain theory has been around for a while.
Serious question. Something in the lizard brain sends a message to the neo-mammalian complex and you start looking for a place to do your being duty.
All of this happens automatically with out an conscious "thinking" on your part.
If we start at the beginning we can get to the conclusion that our biosphere created us to transform minerals into conscious thought.