The time that humans arrived keeps getting pushed back as older artefacts are found - can we plot dates against discovery time to estimate when it asymptotes? (And when we will get there, within some ε.)
The date for Aboriginal Australians is 65,000 ATM. Mongolia seems a similar distance. https://wikipedia.org/wiki/Aboriginal_Australians#cite_note-...
Even stone tools only seem primitive because the plant and animal materials that completed them are gone, unlike metal tools which can be made of 100% durable materials.
My default assumption is that 50k years ago there were human civilizations every bit as rich and comfortable as ours, if not moreso on both counts. And that if you were transported there and taken in by a family you would feel quite at home.
I have never seen any material evidence to the contrary. History for political reasons has discounted the possibility of such civilizations but after many years I finally realized “we have existed roughly the same way for a hundred thousand years or more” is just the null hypothesis.
A few photos here: http://dheera.net/photos/places/mongoliawinter
