The article discusses the challenge of storing and transmitting accumulated cultural knowledge over generations, particularly for forager societies, who use storytelling as a way to encode their knowledge. The authors hypothesize that myth-telling rules exist in these societies to ensure high-fidelity transmission of the stories, and predict that such rules mandate proficient storytellers, low-distraction conditions, multiple individuals and generations present, error prevention and correction, audience attention maintenance, discouragement of rule violations, and incentivization of rule compliance. The authors searched forager ethnographic records for descriptions of myth performance and coded them for these features. Results indicate that rules regulating myth performance are widespread across forager cultures and reduce the likelihood of copy errors. These findings suggest that anthropogenic ratchets played a role in the emergence of cumulative culture.

Aiming to respond to the question "How has knowledge in forager oral narrative been maintained accurately for dozens of generations?", this study explores the myth transmission rules among forager societies. The first hypothesis anticipates that these rules constrain transmission and contexts similarly across forager societies. The authors suggest that these rules are information technology aids to minimize the chances of errors and loss of information. Related to this, the authors formulate eight hypotheses of what these rules will mandate during myth transmission: 1) skilled storytellers to pass down stories, 2) minimal low-distractions, 3) numerous people 4) multiple generations, 5) measures that identify and correct mistakes, 6) measures that maintain the audience's attention, 7) measures that sanction rule violations, and 8) measures that encourage rule compliance. There is enough evidence to support 7 out of the total of 9 hypotheses. These results show the relevance of studying the rules concerning myth and knowledge transmission across generations.

Researchers examined and coded motor skills used in coalitional play fighting in hunter-gatherer societies to investigate if it was a product of agriculture/industry, or occurred more broadly in non-agricultural populations. Sampling 100 societies from the Ethnographic Atlas, researchers found at least one predictor of such motor patterns showing coalitional play fighting amongst all hunter gatherer groups with information, and multiple predictors among most of the 46 groups. Researchers theorize this coalitional play fighting was training for intergroup aggression such as lethal raids.

The authors explore coalitional play fighting (in which teams of at least two play against each other to achieve a goal) across hunter-gatherer societies, with the theory that play of this type may be a mechanism for assessing strength and utility for future defense or warfare. When played against other communities, they propose coalitional play fighting can also serve to gauge strength of potential allies or formidability of potential enemies. In order to test their theories, they predict that, despite the large energy cost and risk of sports associated with coalitional play fighting, these types of games will be widespread in hunter-gatherer societies. In addition, they predict that of those exhibiting coalitional play fighting, many will play against other communities. In support of their hypotheses, they find that 54% of hunter-gatherer societies examined exhibit coalitional play fighting, of which 81% play against other communities.

The association between hunting and sign language is examined. It is hypothesized that sign language develops as a form of nonverbal communication to aid hunters in the coordinated stalking of game. Ethnographic evidence supports this hypothesis. A second hypothesis is also tested concerning the relationship between population size and non-verbal communication, however sampling procedures provided an inadequate test of this hypothesis.

This article offers an exploratory study of the fitness costs of warfare on women. The author examines stories of inter-group conflict cross-culturally and finds that warfare exerts significant selection pressure on women, such as killing or capturing women, or killing their offspring or mate. The author suggests that future research should examine female cognition in relation to these selective pressures.

Researchers coded 473 texts from 53 cultures on suicidal behavior in the Probability Sample Files looking for evidence to support a new theoretical framework called the Costly Apology Model (signaling "I am genuinely remorseful for my actions, and you can trust that I will not do it again," (7)) to explain suicidal behavior that occurs after someone violates one or more social norms. This is theorized to be distinct behavior from the Bargaining Model (signaling "My fitness is genuinely being threatened, and I need your support." (7)) which could explain suicidal behavior after someone suffers harm from another, and from the Inclusive Fitness Model, where suicide occurs as a fitness behavior when an individual cannot reproduce or has a high cost to the fitness of their kin. .

This book chapter tests new and pre-existing theories (Horton, Field, Bacon et al.) for the cause of variation in drinking across cultures. Folktale content is used to test psychological variables more directly than has been done previously. Folktale content is analyzed programmatically with an acknowledged error level of up to one-third. Results lend support to Field's 1962 theory that loose social organization facilitates drinking.

The authors of this exploratory study tested predictions from five different theoretical models for the evolution of ethnoscientific expertise. They claim support for three of the models. They then compared cultural variables and their five models to three different knowledge domains: conceptual (unable to be easily observed), motor (easily observable), and medicinal. Their results indicate that their cultural transmission model is associated with the motor knowledge domain and that their proprietary knowledge model is associated with the medicinal knowledge domain.

The capacity for cumulative cultural evolution has often been invoked to explain the great diversity of habitats occupied by humans. This theory of cultural evolution emphasizes the gradual accumulation of technologies and cultural practices over many generations, and predicts that larger populations will generate more complex cultural adaptations than smaller, isolated ones. Here, the authors investigate the marine foraging tool repertoires of 10 Oceanic societies to determine whether population size and intergroup contact affect the cultural processes by which tool kits evolve.