Gossip and reputation make sure that what comes around - a person who is cruel will find that the others are cruel hack to him, and a person who is kind will find others are kind in return. Gossip paired with reciprocity allow karma to work here on earth, not in the next life. As long as everyone plays tit-for-tat augmented by gratitude, vengeance, and gossip, the whole system should work beautifully.

p. 55 - The Happiness Hypothesis: Finding Modern Truth in Ancient Wisdom (2005)