Quote Originally Posted by texaspackerbacker
So if I put "non-political" in the title, the thread automatically gets transferred over here?

I found this article by a professor from State University of New York saying that it was 60 million in 2 A.D.--about 1/4 the world's population--but it has been anything but a straight line since then. The next 1300 years, it decreased and then just got back to 60 million because of turmoil and rebellions, etc. Then, in the next 500 years to 1851, it increased seven-fold to about 420 million. Then for the next 100 years to 1953, it grew by only about 35% to 580 million. Since then, it has more than doubled in sixty years to the 1.3 billion. Strange fluctuations.

That still doesn't really answer why there are 1.3 billion in China, nearly a billion more in India, and just 570 some million in Europe. China, at least, apparently had its equivalents to the Hundred Years War and the black plague.
More widely accepted birth control in Europe.