Sam Harris: Evolution Doesn't Imply Selfishness.

Many people imagine that the theory of evolution entails selfishness as a biological imperative. This popular misconception has been very harmful to the reputation of science. In truth, human cooperation and its attendant moral emotions are fully compatible with biological evolution. Selection pressure at the level of “selfish” genes would surely incline creatures like ourselves to make sacrifices for our relatives, for the simple reason that one’s relatives can be counted on to share one’s genes: while this truth might not be obvious through introspection, your brother’s or sister’s reproductive success is, in part, your own...

...The work of evolutionary biologist Robert Trivers on reciprocal altruism has gone a long way toward explaining cooperation among unrelated friends and strangers. Trivers’s model incorporates many of the psychological and social factors related to altruism and reciprocity, including: friendship, moralistic aggression (i.e., the punishment of cheaters), guilt, sympathy, and gratitude, along with a tendency to deceive others by mimicking these states.