[TallGuyShort]

http://en.wikipedia.org/wiki/World_population <- Anyone know the reason for the UN's low and medium estimates having serious downturns in population in the next century? Is it because of lowering child-birth rates, or because of expectations of resources/diseases, etc...?

[showerst]

According to the PDF: http://www.un.org/esa/population/publications/longrange2/Wor... it's virtually all due to changes in fertility.

As countries grow in wealth and life expectancy, the number of children per woman tends to drop off drastically.

[ganley]

It's due to zombie apocalypse. Duh.