10,000 BCE: ~4 million people
It seems that I was really born at the wrong time. That population looks much better for introvert like me. Right now I could probably not survive in places like america due to insane amount of people. But in the past that would not had been so much of a problem.
It was likely still a pretty violent place, fighting with other tribes over shiny rocks or something.
I think that the same is true for any time period with humans involved.