Nancy Bovy sent a link to a cool SciAm article that debunks the myth that 75 percent of all people ever born are currently alive.
To calculate how many people have ever lived, [Carl] Haub followed a minimalist approach, beginning with two people in 50000 B.C.—his Adam and Eve. Then, using his historical growth rates and population benchmarks, he estimated that slightly over 106 billion people had ever been born. Of those, people alive today comprise only 6 percent, nowhere near 75 percent. "[It is] almost surely true people alive today are some small fraction of [all] people," says Joel Cohen, a professor of populations at the Rockefeller and Columbia Universities in New York City. [Link]I wonder how many of those 106 billion people left enough evidence of their existence that they may be genealogically (and not just genetically) linked to persons alive today, and how many are ancestors we will never find.