Wasn't there some catastrophe about 200,000 yrs ago
that wiped out all but a few hundred humans, and that we are all now descended from that small cadre? I heard somewhere that genetic evidence suggests that scenario. Perhaps humans reached a fairly high level of civilization in Africa several hundred thousand years ago and then some catastrophic event wiped most of us out, and we're still recovering.
By "high level" I don't necessarily mean flying cars and space travel, but maybe Neolithic or even metal-working. A lot of evidence can be lost in a few 100k years.