Tokens enable cooperation without identification or memory

Indirect reciprocity enables cooperation between strangers when (i) individuals can be recognized and (ii) reputations can be remembered. Here, we show that neither condition is necessary. If reputation is embodied in a recognizable token issued by an arbiter, donors can base their decisions on token possession rather than memory. By allowing for multiple tokens, such an externalized reputational system promotes more cooperation than existing models of indirect reciprocity. This advantage arises from greater robustness to noise and comes despite the absence of individual identification or shared memory. Our results identify a previously overlooked class of mechanisms-object-based reputation-within evolutionary models of cooperation. Since such tokens already possess the structure required for later transfer, they may offer a conceptual bridge between reputation systems and token-based exchange or money.