ABSTRACT
In this chapter and elsewhere (Shackelford & Buss, 1996a, 1996b), I define a relationship betrayal as any instance in which an expected benefit is actively withheld, awarded to parties outside of the focal relationship, or both. Every human relationship is subject to betrayal. Marital partners sometimes commit sexual and romantic infidelities. Best friends occasionally whisper secrets into unintended ears, violating trust. Parents sometimes sexually violate their own children. Betrayal is a significant element of the human “adaptive landscape” (Buss, 1991). Why do we betray those closest to us? When is betrayal likely to occur? Who is most likely to betray us? These are significant questions, yet framed as such they are unanswerable, unless we ask these questions for specific relationship contexts. The actions or events that constitute a betrayal in one relationship context may not constitute a betrayal in another such context (Buss, 1990; Shackelford & Buss, 1996a). I argue in this chapter that to understand betrayal-when, why, and to whom it occurs-we must understand the design of the human mind. To the extent that different relationship contexts
posed different adaptive problems for ancestral humans, different solutions to these adaptive problems will have been selected for and thereby incorporated into the psychological apparatus of the human mind. An evolutionarily in formed perspective on relationship betrayal provides a unique insight into this darker side of human nature.
