that reduced the worldwide human population to fewer than a
dozen individuals

Never heard that one before. Fewer than 12 people remaining, around the
entire globe you say? Yeah, right. I doubt any scientist with an actual
clue believes that.

Well, there *is* a certain well-documented story, very widely known
around the world, about a group of only 8 people left remaining after
a planet-wide calamity wiped out the rest of the human population, but
you probably don't believe that one either.