[gaganyaan]

Asking "Is X conscious" is the wrong question, and is responsible for endless arguments with people talking past each other. The correct question to ask is: "What is X conscious of?" or put differently, "How much of the universe is modeled by X?"

Then we can see that humans are conscious of many things. Cats are conscious of fewer things, but still build a complex model of the world. Sunflowers are conscious of the sun, but probably not much else. Rocks are not conscious of anything.

So it's not that a single-celled organism is not conscious and somewhere, a flip got switched and now humans are conscious. There's just been an ever-increasing ability to model the world as one follows human evolution.

This is also true of the LLMs that are getting built. They're impressively conscious of the world as experienced by humans, since they experience the world through recorded human communications. I would say that GPT-4 is conscious of e.g. what a cat is. Its consciousness of what a cat is came to it differently than humans, since it has no hands with which to pet one, but has an idea of what a cat is nevertheless.