I would argue that intelligence is a tool that life has evolved to become more adaptable to its environment. Intelligence exists at many scales, and consciousne

I would argue that intelligence is a tool that life has evolved to become more adaptable to its environment. Intelligence exists at many scales, and consciousness is an emergent property of high intelligence. At some point, as your model of the world becomes sophisticated enough, you have to have a model of yourself, so you become self-aware. Self-awareness evolved because it made for smarter, more effective animals. Unicellular organisms do information processing and react to their environment. You could say they they're intelligent in that sense, they can actually have very complex behavior. However, they're not self-aware, they don't have a model of the world that incorporates a model of themselves. Neurons involved in multicellular organisms as an effective way to quickly send signals across, making multicellular creatures more adaptable to their environment. These neurons started to organize in more complex circuits that could do increasingly sophisticated information processing because that was good for survival, and so on and so on, until you get self-awareness.