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.

The role of trees has long been limited to being sources of firewood or food in the archeological record. This article, however, aims to investigate the economic, cultural, and spiritual roles of trees through a comparative ethnographic analysis of 13 hunter-gatherer societies. The authors find that the relationships between trees and hunter-gatherers are deep and complex; trees are used for shade, protection, recreation, place-makers, and inhabitation and are often considered social and sacred beings.

Using a sample of 60 societies from eHRAF, this study explores the cross-cultural commonalities and differences in human-pet dynamics. The authors focus on understanding the range of functions of pets and the positive or negative treatment of pets. In addition, they test whether human investment in pets is a significant challenge of evolutionary theory. First, the results support that there are distinct functions of pets, challenging the common view of contemporary function of pets as emotional surrogates. Secondly, the data collected show an ambivalent treatment of pets across cultures, including small-scale societies. Finally, the research does not support the idea that human investment in pets sacrifices their reproductive success.

The authors use ethnographic data to try to shed light on the prevalence of missing phalanges in Upper Paleolithic cave images. Searching eHRAF World Cultures, they found evidence of finger amputation in 121 societies. These accounts cast doubt on two common theories: 1) that cave images reflect sign language or 2) counting systems. Researchers argue the intentional removal of fingers could be sorted into the 10 following categories: sacrifice (for deities), mourning (for grief), identity (for group membership), medical (to heal sickness), marriage (status marker), punishment (for deeds), veneration (for worship), offering (post mortem for deities), trophy (an enemies fingers), and talisman (assist with magic). They argue that sacrifice was the most likely reason for the missing finger images in Upper Paleolithic caves.

This article explores determinants of non-classical polyandry, which the authors assert is more common than is usually conveyed. Results indicate that societies with non-classical polyandry tend to be small scale and egalitarian, practice hunting and gathering or horticulture, and have a male-skewed sex ratio. Overall polyandry is thought to add to the reproductive fitness of both men and women.

Lullabies are often touted as universal to all human cultures, regardless of time and place. In order to test this axiom, this article examines all 186 societies in the Standard Cross-Cultural Sample, and codes them for the presence or absence of lullabies. The result ultimately hinges on the meaning of the word “lullaby”: when lullabies were defined as a strict and culturally conserved repertoire of songs sung to soothe infants, they were found to be neither a statistical nor even a “near” universal. However, when lullabies were defined as any type of singing used to soothe children, they were a near universal, with 96.8% of societies in the sample coded as having lullabies.

Prior research by Oswalt (1973, 1976) and Torrence (1983, 2001) has suggested that risk of resource failure is a significant predictor of toolkit complexity and diversity among hunter-gatherers. In this paper, the same relationship is tested among small-scale herding and farming groups. However, no significant correlation is discovered between any measure of resource risk and any measure of toolkit complexity. The researchers suggest that this absence may be the result of greater reliance on non-technological diversification methods among farmers (i.e. spatial diversification, mixed farming, intercropping), or of other unaccounted-for sources of risk (i.e. intergroup raiding and warfare).

The authors examine a world-wide sample of cultures to assess whether the romantic-sexual kiss is a human universal. They also test for an association between romantic-sexual kissing and social complexity.

Using a sample of 80 countries and political regions, the present study examines the effect parasite stress has on people's trust towards ingroup and outgroup members. The findings do not offer support of there being a concave relationship between parasite stress and ingroup member trust. The results do indicate that there is a U-correlation between trusting outgroup members and parasite stress.

Researchers investigated the variation of land tenure systems across forager societies using the economic defensibility model. The study attempted to explain the variation in tenure systems across 30 hunter-gatherer societies. Using data on defense and sharing of resources among groups, and indicators of resource density, resource predictability, and competition for resources, the researchers were unable to explain the variation. This study highlights the vast range of diversity and complexity of foragers subsistence strategies, and proposes that it may be more telling to conceptualize tenure systems among hunter-gatherer societies as assemblages of multiple property regimes. While there was no overall evidence that environmental variables of resource density and predictability explain variation in tenure systems, researchers did find that increasing population density, and greater competition for resources leads to greater territoriality.