Lots of books apply Darwin's theories to society:
Guns, Germs, and Steel by Jared Diamond is one of my favorites. And, it is a book well respected among most scientists. It plays out like "survival of the fittest enviornmental factors".
Even before that, the Darwinian behavior of memetics was popularized in the end of Richard Dawkins' book The Selfish Gene, which helps us build better models of how societial ideas can form and spread.
Recently, Michael Shermer published Mind of the Market, which, in part, applies Darwin's theories to economics. The results are models that could better predict economic markets, as they emerge in various societies. (Though, this angle is still in its early stages of development.)
Those are just a few examples, off the top of my head.