This Charlie Munger recommendation opened my eyes to a better model of natural selection than I've been using thus far. In The Selfish Gene, Richard Dawkins introduces natural selection at the somewhat (you'll have to read the book to understand just how "some" and "what") gene level, and he shows it to be a powerful model for understanding life.
Until now, I have thought of natural selection as occurring at the organism level. But I now believe this to be erroneous; organisms are but machines used by genes to propagate themselves. Self-aware machines present a principal-agent problem, with interests between genes and human beings, for example, not always being aligned.
Dawkins takes the reader on a tour through a number of topics, such as reciprocity, gender preferences and age differences and applies this model to explain various occurrences in nature. By the middle of the book, I found that I was able to apply his model before reading his explanation, as it is intuitive and easy to understand.
He makes his case using a great number of fascinating examples from the animal (and sometimes plant) kingdom, ensuring the reader is never bored.
My chief quibble with the book is that Dawkins sounds a little bit too sure about some things that we probably can't be sure about.
I highly recommend The Selfish Gene