In percentage terms, WORLD WAR ZERO WAS FAR WORSE than WW1 and WW2 combined, and the bad guys seem to have won. Remember the Beach Boy song Surf City, that had the line, “Two girls for every boy?” Well, paleo genetic studies have detected a severe Y chromosome bottleneck over the span of 5,000 to 7,000 years ago. It was so severe that at one point there was only ONE MALE TO MATE WITH EVERY 17 WOMEN.
What caused this bottleneck? Most scientists now believe it was genocide – a dominant group of men (the Bell Beaker people) would sweep into new lands and kill all the men, then seize the women for themselves. Their success would then allow them to expand farther. Mitochondrial DNA indicates that the female population increased throughout this time, so just the men were targeted.
Since the world population at this time was probably about 20 million, this suggests that about 9.5 million men were killed. To get the same effect today, 3.3 BILLION men would have to die. WOW!