"Guns, Germs and Steel", by Jared Diamond
It explains the reasons why Eurasian civilizations ended up "on top" while the natives of the Americas, Australia and Polynesia didn´t. He shows that this has nothing to do with race or culture, but instead (in a nutshell) with the availability of food crops and domesticable animal species, which our ancestors had or could introduce, and the natives of the Americas, Australia, Polynesia and much of Africa didn´t have (for the most part) or could not get from anywhere.
Well written, very informative, and a good antidote to racist pseudoscience - I really recommend it.
Bizarrely enough, that's the one I just picked off my stack of 'To be read' to read next!
Just the first book in Harry Turtledove's Settling Accounts series, Return Engagement. First book of his I've ever read, and I quite liked it.
Meditation on inevitable death should be performed daily.