The world population in the year 1500 is estimated to be about four hundred and fifty million (450,000,000) people.
If you start counting all your direct ancestry - exponentially: two grandparents; four great grand parents; eight great-great grand parents; sixteen g-g-g grandparents etc. the number of your ancestors exceeds the population of the Earth about the year 1450 (around 1450 you exceed five hundred million direct ancestors.) After that, by following reverse population growth your ancestry begins to collapse toward an original Eve; or Australopithecus Africanus: an original Lucy to be more exact.
|Lucy and Luke - the alpha ancestors.|
Note: no apple trees and snakes - just reverse evolution.