This paper examines the relationship of productive variation in land between ethnic groups to determine if an increased range of producible goods will increase trade, thus decreasing language diversity between neighboring groups. The author initially found that high-variation in land production lessened the diversity of language between ethnic groups in that area. To further test this correlation, the author found that high-productive variation increased trade and exogamous marriage and decreased inter-ethnic conflict. Based on these findings, the author suggests that neighboring ethnic languages co-evolved through the economic benefit of inter-ethnic trade and social interaction.

Theories about the relationship between warfare, militarism, male dominance and authoritarianism are tested.

This study tests the weaning food availability hypothesis, that both the introduction of foods other than breastmilk and the cessation of breastfeeding will vary by society's subsistence type. This hypothesis has implications for demography, as accelerated weaning can lead to increases in both mothers' fertility (due to decreased birth intervals) and infant mortality (due to the presence of pathogens in new foods).

This study tests for a relationship between subsistence type and fertility using phylogenetic and statistical analyses. The authors find a clear relationship between dependence on agriculture and fertility among non-permanently settled groups.

This study focuses on the relationship between pathogen prevalence and mate selection. Results show that increased pathogen prevalence is significantly associated with an increased importance in the physical attractiveness of potential mates.

"An exchange theory of social behavior is advanced to explain intersocietal differences in sex codes…[Results indicate] modest support for the thesis that the location of power and resources as they influence social interaction and exchange are contributory forces in accounting for the level of sexual permissiveness found in society" (1).

This study presents a sociological theory of marriage type based on socioeconomic organization. Results suggest that intensive agriculture, more stratification, greater political integration, a fixed settlement pattern, a larger population, and greater labor specialization tended to be correlates of monogamy.

This study uses a multiple regression analysis to examine the relationship between society type and several variables of societal organization. Results suggest that limited family type is more likely to be found in complex societies.

This study looks at the relationship between the presence of love magic in a society and sexual anxiety. Results show support for the hypothesis that love magic is positively correlated with sexual anxiety.

This study first reviews two explanations of menstrual taboos: taboos as an aspect of social rigidity and a psychogenic interpretation of menstrual taboos. The authors chiefly advocate a sociogenic explanation of menstrual taboos.