Some people think that consciousness, and conscious thought, is an emergent phenomenon, like an ocean wave. The ocean is made of billions of drops of water that all exist independently yet held together in a collective sea. You can't add or subtract a single wave from the ocean, yet the movement of water within oceans creates waves. Waves don't have any existence outside of oceans, they are an emergent phenomenon of oceans. And maybe conscious thought is an emergent phenomenon of the highly advanced brains of living things.