Why are 90 percent of the people living on 10 percent of the land area?

because you have to count Antarctica's land, the many small and un-inhabited islands, not to mention that 1/32 of the world is farmland, and that there is the savannah in aferica, The tundra in Russia and Canada, and the fact that there is the rockies in america, and the indian reservation, and national parks world-wide, etc. In the end, you have to count all the land that people have affected, like dumps,

where we don't actually live, but where we have affected, so you end up with a little less than 1/3.