When I was in the 4th grade, back in the late fifties, it was a big deal to learn that the world population had, for the first time, popped the 3 billion mark. Everybody seemed upset that the world was getting too crowded, that we'd eat ourselves out of house and home and heat up the planet. They were actually thinking this would happen. Nuts.
Next year we'll pass the 7 billion mark. Good job everybody. Keep on doing what you're doing.