For most of human evolution, accumulated cultural knowledge has been stored in memory and transmitted orally. This presents a daunting information management problem: how to store and transmit this knowledge in a portable format that resists corruption. One solution–widespread among foragers–is to encode knowledge in narrative. However, this strategy depends on accurate performance of the story. Significantly, some forager cultures have rules regulating myth performance, although the extent of this phenomenon is unknown. We hypothesize that these rules subserve high-fidelity transmission across generations. Accordingly, we predicted that, across forager cultures, myth-telling rules will mandate: (P1) transmission by the most proficient storytellers (P2) under low-distraction conditions with (P3) multiple individuals and (P4) multiple generations present, and the application of measures that (P5) prevent, identify, and/or correct errors, (P6) maintain audience attention, (P7) discourage rule violations and/or (P8) incentivize rule compliance. To test these predictions, we searched the forager ethnographic record for descriptions of myth performance, and coded them for prescriptions/proscriptions regarding narrator age, performance context, audience composition, narrative delivery, and audience comportment, as well as sanctions associated with rule transgression or compliance. Results indicate that rules regulating myth performance are widespread across forager cultures, and are characterized by features that reduce the likelihood of copy errors. These findings help elucidate the role that anthropogenic ratchets played in the emergence of cumulative culture.