Nonlinear Dynamics, Mathematical Biology, And Social Science
Joshua M. Epstein
Westview Press
If you were ever at all comfortable with integral calculus and differential equations, for example if you took these in college, then J. Epstein's book is a wonderful breezy read through a smorgasbord of social science and biology.  The book covers a series of his mathematical lectures on combat, arms races, revolutions, drug epidemics, ecosystems, etc..  All the while, he weaves threads of connectivity between the topics.  

This is not a book of proofs.  Rather, it reminds me of what the book Freakonomics might have been like if it had equations.  [By the way, I wish everyone in the world could get to page 82 of this book, to gain an insight into the ideas of herd immunity and decentralized totalitarianism.]  Although the book does linear and nonlinear treatments throughout, the final chapter/lecture delves more deeply into understanding the issues of nonlinear models.  Unfortunately, I am now left with a thirst I cannot slake, the thirst for the next few chapters after I've finished the book.  Joshua, when can I get the next one??