We often think of playing fair as an altru­istic behavior. We're sac­ri­ficing our own poten­tial gain to give others what they deserve. What could be more self­less than that? But new research from North­eastern Uni­ver­sity assis­tant pro­fessor of phi­los­ophy Rory Smead sug­gests another, darker origin behind the kindly act of fairness.Smead studies spite.