Why doesn't crime pay better?

Why aren't we all criminals?
Why weren't trusting homonids driven to extinction a million years ago?

Prisoner's Dilemma Tournaments

In a typical business transaction there are four possible outcomes:

Both parties are honest-- each benefits moderately
A cheats B-- A benefits greatly, B does not benefit
B cheats A-- B benefits greatly, A does not benefit
Both parties cheat-- each benefits slightly

If every turtle interaction is an instance of this game, we expect to see cheaters dominating coopoerators.

Vindictiveness

A is vindictive if he has a tendency to punish cheaters, even at a personal cost.
Adding vindictiveness to the transaction tips the balance back toward the trusters.