This article discusses the variation in sex ratios at birth among human populations and the possible explanations for this variation. One possible explanation is the timing of intercourse and its relationship to the frequency of intercourse, which can affect the timing of conception. The article presents evidence that the male/female sex ratios of 148 countries declined with total fertility rates and polygyny intensity and increased with contraception use in correlational analysis. These results were independent of mother's age and level of economic development. The predictive effect of polygyny and contraception disappeared when total fertility was added to the equation. The article also considers other possible explanations for the variation in sex ratios, such as genetics, hormones, nutrition, and social factors.

Can physiological variation in human populations be attributed to environmental variables? Arguing for the importance of phylogenetic comparative methods, the authors present the results of previous research by Holden & Mace (1997) on lactose intolerance as well as introduce new research on sex ratio at birth. The authors suggest that global variance in sex ratio at birth is an adapted response to the physiological costs of giving birth to boys in high fertility populations.

The present study attempts to replicate the Barber (2011) finding that more considerable security influences a country's disbelief in God. However, this research uses a more diverse sample and seeks to answer additional questions about religiosity and security than the previous work. The results are in line with all of the predictions and offer extra support to the uncertainty hypothesis.

This study investigates the relationship between historical utilization of the plow and modern sex ratios. The authors argue that in societies without the plow subsistence is generally egalitarian with both men and women contributing. However, the use of the plow requires more physical strength which, they argue, leads to a preference for boys and, thus, men. Therefore, in cultures that use the plow, this is reflected in male-biased sex ratios which are negotiated by way of practices like sex-selective abortions, infanticide, and/or differential access to resources based on sex.

What explains global variation in sex ratio at birth? To address this question, the authors present the results of their previous research on sex ratio at birth (2003), and additionally introduce new research on the correlations between sex ratio and marriage costs, such as a dowry or brideprice. Using a phylogenetic approach, the authors find that there is no correlation between sex ratio at birth and marriage payments. Analysis is restricted to the Old World.

This study provides the first tests of the relationships between population-level adolescent fertility rates and mortality risk at two different time points. The hypotheses are based in life-history theory, which predicts that human reproductive choices are shaped by mortality. The authors find that reproductive strategies are significantly predicted by both early (between ages 1-7) risks of mortality and current cues of mortality risk.

Researchers looked at four different demographic scenarios (altered mean vital rates (i.e., fertility and mortality), vital rate stochasticity, vital rate covariance, and periodic catastrophes) and their possible effects on the rapid population growth of contemporary human foragers and steady population decline of chimpanzees. They evaluated these variables and the various conditions that would favor a more sustainable zero population growth (ZPG) among 10 small-scale subsistence human populations (Agta, Ache, Hadza, Hiwi, Ju/’hoansi, Gainj, Tsimane, Yanomamo, Northern Territory Aborigines, and Herero) and five wild chimpanzee groups (Gombe, Kanyawara, Mahale, Ngogo, and Taï). The results state that the most effective modifications towards ZPG would include a combination of more than one of the four demographic scenarios tested, with the most realistic solution including both vital rate alteration and an increase in catastrophes.

This article explores how the evolutionary psychological perspective explains cultural universals and variations. This framework is then used to test whether wealth affects parents' preferences of sons or daughters on an individual and national level. Results suggest that wealthier individuals and wealthier nations prefer sons to daughters.

There is disagreement between existing theories on the relationship between leisure time and cultural complexity. This study tests Chick's (1986) hypothesis that simple and complex societies have more free time than those of moderate complexity. The relationship between cultural complexity and the economic productivity of children is also examined.

The study looks at 137 countries and examines the relationship between disbelief in God and increased security in health, economic development and security. The findings provide additional support for the uncertainty hypothesis as there is a positive relationship between a country's health or financial growth/security and the population's disbelief in God.