Great thread. Some of the recent posts have forced me into research mode, and almost immediately I discovered that an observation I made early on was absolutely wrong. I said that there are more people alive today than ever lived. Apparently, this idea comes from some zero population growth people in the 1970's. This article
How Many People Have Ever Lived On Earth? seems to make a lot more sense.
As far as the question of ancestry, I went right to The Straight Dope and turned up this page:
2, 4, 8, 16 ... how can you always have MORE ancestors as you go back in time?
This kind of discussion makes my brain happy.
