outhouse
Atheistically
According to Greg Graffin in his book Anarchy Evolution, we only need to go back 1000 to 2000 years before we find a common ancestor of any two random people.
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I think greg drinks to much lol.
I know very little has changed in the last 2000 years
I believe our population was bottlenecked around 48000 years ago wih a volcanic event.