Short answers, pulled from the story.
In 1643, the English poet John Milton used the word conscious to describe a grove of trees, marking the first recorded instance of the term applied to inanimate objects.
René Descartes was the first philosopher to use the Latin word conscientia in a way resembling modern consciousness when he wrote of internal testimony in 1651.
In 1974, the philosopher Thomas Nagel published a paper titled What Is It Like To Be A Bat, introducing the idea that consciousness is defined by the subjective character of experience.
In 1994, physicists Roger Penrose and Stuart Hameroff proposed the orchestrated objective reduction theory, suggesting that consciousness originates at the quantum level inside neurons.
Humans older than 18 months, great apes, bottlenose dolphins, orcas, pigeons, European magpies, and elephants have all been observed to pass the mirror test for self-awareness.
The two most widely accepted altered states are sleep and dreaming, each associated with distinct patterns of brain activity, metabolic activity, and eye movement.