ABSTRACT
This chapter considers the type of cooperation among humans in situations in which the temptation to defect exists. It addresses how effective signals and symbols evolve to facilitate cooperation. Two kinds of symbols are important in facilitating human cooperation: cultural and reputational symbols. The chapter argues that the ability of humans to use signals and craft symbolic systems facilitates cooperation in nonrepeated interactions and stimulates the development of complex social organizations. The ability of humans to detect those signals and to behave contingently based on the detected signals is the fundamental biological mechanism that supports human cooperation at a remarkable scope and scale. Biological signals, such as facial expressions, body language, eye movement, and tone of voice, can be reasonably reliable under certain conditions. Over time, the use of artificial symbols to establish, to convey, and to detect reputation has brought forth the possibility of human cooperation on unprecedented scales.
