Well, in the real world I don't believe in Good, Evil, Ghosts, Spirits, G_d or gods, demons, an afterlife, or the human soul. However, in fiction I like all of the above, and in human social interactions many of the above beliefs are very useful, whether they reflect a core reality or no. It's all very well if you believe on an abstract level that both you and the people you deal with daily are meat machines, but as soon as you start believing that on an emotional level and (more importantly) acting accordingly, your ability to engage in healthy and necessary social interactions falls to bits. As to Selfishness, I wouldn't say it's a better strategy for genetic or personal survival than altruism. Historically, our best survival strategy was the formation of pair-bonds and group alliances, both of which require social interaction and some level of personal sacrifice (the root of altruism). Parents that fail to care for their children have reduced the chances that those children will survive long enough to pass on their genes; people that fail to form friendships and alliances with others have reduced their own chances of survival, and those of their children. Even apparently reward-free altruistic acts, such as caring for the sick and elderly, can improve the survival chances of the individual and that individual's offspring through group dynamics. Eve the cave-woman cares for her sick relative, gaining nothing directly in return; however, the social allies of that sick relative may now feel some obligation towards Eve and her children, increasing the strength of Eve's ties to the group and increasing the aid that she can hope to receive in the future. Even apparently self-destructive altruistic actions may be very pro-survival from a genetic point of view. If Adam the hunter-gatherer risks his life to save a drowning child not related to him, he has inflicted an obligation upon the child's parents, strengthened his ties to his group, increased his group status, and helped to preserve variety in the group's gene pool. He may die, but the increase in the chances of genetic survival (the survival of his blood-line) may be worth the risk. At the same time, selfishness is also a useful and necessary survival strategy. It grants an immediate pay-off in increased resources, in exchange for the risk of social stress. Considering how dependant humans have been on their immediate families and family-groups/tribes for survival throughout our evolutionary history, this risk is something to be taken seriously. A human forced out of the group due to excessive selfish and anti-social behavior has historically been much less likely to survive or pass on his genes. Both altruistic and selfish survival strategies may be pursued simultaneously, and generally are. "The Ant and the Peacock" by Helena Cronin and "The Anatomy of Love" by Helen Fisher are both good reads on this topic, and a lot of Robert Sapolsky's stuff relates back to it (though he is more concerned with health issues).