Reply to McNally and Tanner: Generosity evolves when cooperative decisions must be made under uncertainty
- Andrew W. Deltona,b,1,
- Max M. Krasnowa,b,1,
- Leda Cosmidesa,b, and
- John Toobya,c
- aCenter for Evolutionary Psychology and
- Departments of bPsychological and Brain Sciences and
- cAnthropology, University of California, Santa Barbara, CA 93106
We thank McNally and Tanner (1) for their considered critique of our article (2). Our article addressed the puzzle of why humans, in one-shot interactions, often choose to incur costs to allocate benefits to others, with no possibility of recouping these losses (i.e., “irrational” generosity) (2). This empirical pattern challenges standard models of economic and evolutionary rationality, and has prompted the development of ever-more-cumbersome explanations (e.g., group selection, gene–culture coevolution, cultural group selection)—models fragilely dependent on many hard-to-verify assumptions. In our article, we demonstrated that the well-documented selective regime of direct reciprocity produces agents willing to cooperate in apparently one-shot encounters, when the …
↵1To whom correspondence may be addressed. E-mail: andy.delton{at}gmail.com or max.krasnow{at}gmail.com.
