> Actually, the successful game theory strategy is "tit for tat" > > which would be quivalent to: "an eye for an eye" >
Sure, but the "tit for tat" can just as easily mean "one good deed deserves another" Ultimately, the successful game theory strategy is to "win" (increase fitness and/or resources, survive...) whether that be accomplished via competition, cooperation, or arguably even "altruism" (raising probability that some "stranger" will in the future bail you out of a bind by acting in kind now). It may all be seen ultimately as "selfish", but if by poking out the eye of a fellow clansman that just managed to poke one of yours out, you then ruin the depth perception of a clan spearman who is otherwise watching your and your families "back", well..