BTW about the "8 billion from 8 in 4400 years" part:
Since coding is part of my own career, I also made a program trying to confirm that statement.
And it turned out to be very plausible and accurate: one can easily simulate the growth of a population of around 8 billion people in around 4400 years, starting out from a family of just 8 members (4 males plus 4 females).