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 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.

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. .

In asking whether or not there are meaningful universals in music, researchers compiled two catalogs – the Natural History of Song (NHS) Ethnography which contains ethnographic descriptions of song performances collected from eHRAF World Cultures, and the NHS Discography, which contains field recordings of performances of dance, healing, love, and lullaby. Using these two corpora, the study tests a variety of hypotheses about the universality and variability of both music behavior and music form. Specifically, whether there are meaningful universals in meaning and sound. The catalog of published sound recordings was analyzed by machine summaries, listener ratings, and manual transcriptions, which revealed that there were identifiable features of songs which could then predict their primary function cross-culturally. The results as a whole revealed that the existence of music is a cultural universal, and that the variation within music can be characterized by three factors assessing the formality, arousal, and religiosity of the song events. They also found that musical behavior varies more within societies than between them.

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.

Archaeologists often interpret found portable artifacts (e.g. dolls, miniature weapons) as ritual objects. But it is argued that they might instead reflect children's play activities. This descriptive study analyzes the artifacts and context of children's play using the literature and the ethnographic record of 82 hunter-gatherer societies. Six signs of the presence of children, that might survive in archaeological record are noted, which may suggest that many "ritual activities" are children's activities.

This article builds upon gender inequality theory to examine childhood gender inequality in preindustrial societies. Multivariate and cluster analysis are used.

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.

Acerbi, Kendal, and Tehrani examine the relationship between population size and cultural complexity as measured by a non-technological cultural domain: folktales. Three measures of complexity for folktales are analyzed, 1) number of tale types, 2) number of narrative motifs, and 3) number of traits in variants of two international folktales. Findings suggest that the relationship between cultural complexity and population may depend on the domain, as different domains vary in cultural maintenance and transmission.