The theory of natural selection is farther-ranged than just animal evolution.
Any sort of system that can be considered more or less fit based on outside interaction, is influenced, to some extent, by natural selection. A society can be judged based on the numbers it attracts and its power, wealth, and territory compared to other societies.
Our society has evolved to attract people to join it, and, naturally, to attack those who oppose it. Any society that welcomes dissent and proponents of change isn't going to be around very long. There are several ways our society protects itself:
Capitalism: Our economic system forces people to make themselves useful to the society or face starvation. If a person wants to exist in a simpler way, say living off the land, he or she is attacked in the form of economic restrictions to access of land, advertsing providing desires for things that require money to obtain, and mandatory taxes, even if the person lives witout money.
Law: The law exists, supposedly, to protect the individuals of the society. The real purpose, of course, is to protect the society itself. Any act that may threaten a society is, in some way, against the law.
Meaning: By abstracting the process of survival to a simple game, society removes the one thing that gives humans an obvious purpose in life. A replacement is offered, in the form of consumerism or religion, but, these things are, of course, controlled by society.
Our society takes on a life of its own, with its own interests. It does what it must to protect itself. These interests sometimes run counter to our own, which is why it is sometimes necessary to take a stand contrary to the popular belief. A society does not not live independantly. It exists within each of us, making it all the more insiduous.