We're still waiting on you to define consciousness, and I really hope you realize that at one time homo sapiens and neanderthals existed during the same time period. I also have a question. If a tribe of humans today are living similarly to tribes of humans thousands of years ago, are they not conscious either?
I think every human since Adam has been conscious, and I think thats when civilization began. Thats where I track its beginning.
Now let me define Consciousness in short order. You and I reconize each others consciousness, so " Seeing the Consciousness of Others", our personal Identification with other living things, is a sign of Consciousness. When we can imagine what they " Are Thinking", and feel sympathy for it. And then " Remember it from then on , that is consciousness. Animals and cavemen have " Synaptic nervous systems, that does not allow this, only instinct and reaction. Instinct and reaction can build tools and bury the dead, but they will never " Remember the dead again." This is why I disagree that Consciousness can evolve by biological selection. There is no memory in biological selection.
The Intellectual ability of civilizied man is his Consciousness, his culture, history( memory) even religion and science are signs of Consciousness. Animals have no science, no religion, no language, no imagination, no thinking about what the other is thinkling about, all this is consciousness. Consciousness is more than human evolution from mere chance, matter and survival. Something must be " Added from the outside" in order for something as different as Consciousness to occur, of course I believe that added ingredient comes from God.
For further example; Mans consciousness couldnot have possibly developed by means of the same laws which have determined the progressive development of the organic world in general, mans simple physical organism is vastly differing.
Consciousness is not important in animals or cavemen, they didnot need it to survive.
Peace.