BTW: The longest recorded family tree is that of Confucius which goes back 80 generations. 
Keep in mind, there are tribes living in "neolithic style", with little or no clothing, no tools besides rocks, etc. still today. The existence or even domination of such people doesn't determine the timing of the "dawn".
500 years later, a HN user from Mars (or may be even a Belter):
"12000 years is such a short time span. It is crazy how close to the dawn of man you find yourself living in."
Edit: just to provide a little more color, “Sapiens: A brief history of humankind” is a brilliant book on our evolution as a species. One of the striking things about it, IMO, is how vividly it presents the timeline.
So are they just literally making things up? This reminds me of Motel of the Mysteries. http://sultanaeducation.org/wp-content/uploads/2014/06/Motel...
Yuval Noah Harari in A Brief History of Humankind argues that it the need to feed so many workers could lead to deliberate domestication of wild grains and the agricultural revolution. (All in all, I do not recommend the book).