Thriving on Selfishness; April 2009; Scientific American Magazine; by Marina Krakovsky; 2 Page(s)

It¿s the altruism paradox: If everyone in a group helps fellow members, everyone is better off¿yet as more work selflessly for the common good, cheating becomes tempting, because individuals can enjoy more personal gain if they do not chip in. But as freeloaders exploit the do-gooders, everybody¿s payoff from altruism shrinks.

All kinds of social creatures, from humans down to insects and germs, must cope with this problem; if they do not, cheaters take over and leech the group to death. So how does altruism flourish? Two answers have predominated over the years: kin selection, which explains altruism toward genetic relatives¿and reciprocity¿ the tendency to help those who have helped us. Adding to these solutions, evolutionary biologist Omar Tonsi Eldakar came up with a clever new one: cheaters help to sustain altruism by punishing other cheaters, a strategy called selfish punishment.