This paper seeks to identify how different practices of food sharing are related to one another, and the degree to which societies in North and South America may share practices with one another. The authors attempt this by using ethnographic literature to break sharing activities down into their constituent, multi-stage parts, and then comparing the prevalence of these parts and their relationships to one another. The study finds that the presence or absence of a distributor in a sharing activity, and who that distributor is, has a significant effect on how sharing is carried out. On the other hand, linguistic relationships between groups seem to have little impact on their sharing practices, and geographic proximity between groups only seems to have a significant effect on sharing practices in North America.

This study, primarily a review on the evolution of the human diet, also includes a small study on the distribution of meat-eating and its relationship with climate and cultural factors, namely subsistence type. The authors find that societies with subsistence strategies that prioritize fishing, hunting, or pastoralism also tend to consume more animal products, whereas those that focus on agriculture have more plant-based diets. The authors argue that these small-scale societies have a healthier approach to diet than industrialized societies regardless of their subsistence type or meat consumption.

The second and third parts of this book classify the economic systems of foraging and agricultural societies in the SCCS based on correlations between their institutions of property an distribution. These economic types are then examined for relationships with other social, political, demographic, and environmental factors in order to draw tentative conclusions regarding the origins of the Agricultural and Industrial Revolutions. The fourth part of the book uses cross-national data to examine similar associations in industrial/service economies, and is not included here.

The present research investigates food sharing and labor sharing practices of 98 nonindustrial societies. The aims are to: 1) document the frequency and scope of sharing, and 2) test the theory that greater sharing is adaptive in societies subject to more resource stress (including natural hazards).

This study examines three theories of the origin of the plow. The author rejects the universalist approach on the basis that not all cultures that are aware of the plow adopt its use. Findings provide partial support for a theory focused on population density, particularly the importance of fallowing practices and labor productivity. The author’s own ecological approach, pointing to a culture’s staple food as a crucial variable, also receives empirical support.

Inter-group variation is greater in humans than in any other animal, and scholars continue to debate the cause of this diversity. Two competing explanatory models of human variation emphasize either (1) ecological differences and "evoked" culture or (2) population-level effects of cultural transmission. The former emphasizes mechanisms that operate within a single generation, while the latter emphasizes cumulative cultural history operating over many generations. To test these competing models, the authors measured the relative power of ecological variables as compared to culture history to predict behavioral variation in 172 western North American tribes. Culture history is subdivided into culture phylogeny (based on language phylogeny) and spatial distance.

This book investigates individual and group responses to death and the problems that death can create in a society. Several hypotheses regarding grief and mourning, as well as their variation with other societal variables, are supported with cross-cultural tests.

Building on previous research concerning murder and suicide, this study investigates 18 forms of aggression and explores how they might be engendered by certain child-training practices. Results show a weak connection between most forms of aggression and child-training practices, but non-literate societies do show a positive correlation between murder and suicide. The author develops a theory positing that experience of social blockage will be related to outwardly-directed aggression, whereas social loss will be related to inwardly-directed aggression.

This study explores the evolution of family systems in non-industrial agricultural societies based on environmental conditions. First, the authors conduct a multi-evolutionary simulation for each family system: absolute nuclear families (nuclear with unequal inheritance), egalitarian nuclear families (nuclear with equal inheritance), stem families (extended families with unequal inheritance), and community families (extended families with equal inheritance). Second, they use Spearman's rank correlation analyses to assess the relation between the 186 non-industrial societies and the types of inheritance relationships, either parent-child (nuclear or extended) or inter-sibling (strongly biased or equal). The results show that the four core family systems are related to wealth and land resources. Other relevant findings are that low polygyny is related to agricultural societies, higher poverty levels to extended families, and accelerated wealth accumulation to strongly biased inheritance.

The authors examine degree of intensiveness (kin-relatedness) among foraging and agropastoralist societies, predicting that hunter-gatherers will pursue more extensive kinship networks in order to maximize residential options in the case of unpredictability or uneven geographic distribution of food resources. Support is found for the hypothesis, and it is suggested that while extensive fission-fusion dynamics are beneficial in foraging systems, the increase in cooperation in large-scale agricultural settlements is aided by norms which encourage kin marriage and relatedness.