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.

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.

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.

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.

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.

Previous research into the origins of human violence and warfare has oftentimes been inconclusive and controversial. This paper examines two alternative theories as to the evolution of human violence using archaeological records on sharp force trauma (SFT) and blunt force trauma (BFT). The study is limited to 13 different California ethnolinguistic groups. Researchers find that violence is not predicted by sociopolitical complexity, but rather by environmental productivity. This supports the idea that in contexts of resource scarcity, the perceived benefits to engage in lethal aggression may outweigh perceived costs.

The authors evaluated an alternative theory to the traditional productivity theory. They posit that food surplus did not precede the emergence of hierarchy, rather, the productivity advantage of cereal cultivation over tubers and roots as the catalyst for state societies. Their theory found support with a sample of societies from the present-day, Classical Antiquity, Neolithic period and pre/post Columbian Exchange. The results suggest social complexity emerged with cereal cultivation, rather than agriculture alone.

In an attempt to explain communal conflict, this study investigated how customary institutions (i.e. legislatures, courts, and chiefs) may impact the communal conflict activity of groups in Africa. The authors suggest that customary authorities act as local enforcements to mitigate within-group conflict, therefore a higher number of customary institutions should decrease communal conflict. Using data from 143 politically relevant ethnic groups, the authors showed support for their hypothesis and demonstrated marginal support that more inclusive customary institutions would be associated with less communal conflict.

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

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