Genetics is the cornerstone of modern biology and understanding genetics is a critical aspect of scientific literacy. Research has shown, however, that many high school graduates lack fundamental understandings in genetics necessary to make informed decisions or to participate in public debates over emerging technologies in molecular genetics. Currently, much of genetics instruction occurs at the high school level. However, recent policy reports suggest that we may need to begin introducing aspects of core concepts in earlier grades and to successively develop students' understandings of these concepts in subsequent grades. Given the paucity of research about genetics learning at the middle school level, we know very little about what students in earlier grades are capable of reasoning about in this domain. In this paper, we discuss a research study aimed at fostering deeper understandings of molecular genetics at the middle school level. As part of the research we designed a two-week model-based inquiry unit implemented in two 7th grade classrooms (N=135). We describe our instructional design and report results based on analysis of pre/post assessments and written artifacts of the unit. Our findings suggest that middle school students can develop: (a) a view of genes as productive instructions for proteins, (b) an understanding of the role of proteins in mediating genetic effects, and (c) can use this knowledge to reason about a novel genetic phenomena. However, there were significant differences in the learning gains in both classrooms and we provide speculative explanations of what may have caused these differences.

State indiscriminate violence against civilians has been viewed as counterproductive for the government. This conclusion hinges on the assumption that indiscriminate violence aggrieves civilians against the government even when the rebels provoke the state by using civilians as human shields. An alternative view suggests that civilians recognize if the rebels exploit them as human shields and blame the rebels if such provocation occurs. We ask: do civilians evaluate all state indiscriminate violence in the same way or do they think of state indiscriminate violence differently when it is provoked by insurgents? Accounting for the covariate differences between individuals with and without personal experience of warfare in the survey data from postwar Ukraine, we find that personal exposure to violence shapes one’s blame attribution for provoked state attacks on civilians. Individuals unexposed to violence tend to take into account whether the government was provoked by the rebels. By contrast, individuals with personal experience of warfare tend to blame the government for indiscriminate attacks regardless of rebel provocation. This finding has implications for counterinsurgency scholarship and policy. It is likely that the difference between unexposed and exposed to violence civilians emerges in geographically isolated conflicts. If so, targeting of civilians may have different effects on the escalation of insurgency in geographically concentrated as opposed to widespread cases of violence.

Hammond and Axelrod use an evolutionary agent-based model to explore the development of ethnocentrism. They argue that local interactions permit groups, relying on in-group favoritism, to overcome the Nash equilibrium of the prisoner’s dilemma and sustain in-group cooperation. This article shows that higher levels of cooperation evolve when groups are dropped from the model, breaking the link between ethnocentrism and cooperation. This article then generalizes Hammond and Axelrod’s model by parameterizing the underlying geographical assumptions they make about the evolutionary environment. This more general model shows that their findings are sensitive to these assumptions and that small changes to the assumed geography of reproduction significantly affect the probabilities of finding “ethnocentric” behaviors. The model presented here indicates that it is not local interactions, per se, but settings where interactions are highly likely to be with close relatives that lead to “ethnocentrism” as modeled by Hammond and Axelrod.

This article uses an agent-based model and Selectorate Theory to explore the micro-foundations of the systemic democratic peace. Leaders engage in an international bargaining game that can escalate to conflict. Upon resolving the dispute, leaders distribute winnings to domestic constituencies and stand for reselection. The model’s assumptions about selectorate size in a democracy versus an autocracy make democratic leaders more accountable than autocrats and endogenously generates the dyadic democratic peace. The model shows no evidence of an autocratic peace, as mixed dyads are less likely to go to war than autocratic dyads. I further show that democratic leaders invest more resources in wars than predicted by the Nash equilibrium and also more than autocrats. This overinvestment by democratic leaders results in democracies winning more wars than autocrats. This model thus reinforces previous findings that democratic leaders respond to domestic reselection incentives by using more resources in conflict to gain a war-fighting advantage and help ensure victory. Finally, consistent with empirical results, I show that increasing the percentage of democracies in the system does not have a linear effect on the amount of conflict in the system. Below a certain threshold, increasing democracy has no effect on conflict, while after this threshold conflict decreases.