I haven't read through all 4 pages but have you all mentioned eugenics in this 10,000 year span? Lots of european emperors and oriental kings sent literally millions of viable mate-aged vigorous males either to their premature deaths, or just relocated them to different populations.
"Ah, those endless forests, and their horror-haunted gloom! For what eternities have I wandered through them, a timid, hunted creature, starting at the least sound, frightened of my own shadow, keyed-up, ever alert and vigilant, ready on the instant to dash away in mad flight for my life. For I was the prey of all manner of fierce life that dwelt in the forest, and it was in ecstasies of fear that I fled before the hunting monsters."
Jack london, "Before Adam"