Games Eton 8ehav 9819-33. 27. Leimar 0, Hammerstein P (2001) Evolution of cooperation through indirect reci- procity. Prot R Sot 8 268745-753. 28. Pandianathan K. Boyd R (2003) A tale of two defectors: The Importance of standing for evolution of indirect reciprocity. f Theor Biol 229:11S-126. 29. Suzuki S. Akiyama