Offensive realism, a theory of international relations, holds that states are disposed to competition and conflict because they are self-interested, power maximizing, and fearful of other states. Moreover, it argues that states are obliged to behave this way because doing so favors survival in the international system. Debate continues as to whether modern states actually do, or should, behave in this way, but we are struck by a different question. In this article, we ask whether the three core assumptions about behavior in offensive realism—self-help, power maximization, and outgroup fear—have any basis in scientific knowledge about human behavioral evolution. We find that these precise traits are not only evolutionarily adaptive but also empirically common across the animal kingdom, especially in primate and human societies. Based on these findings, we hypothesize that states behave as offensive realists predict not just because of anarchy in the modern international system but also because of the legacy of our evolution. In short, offensive realism may really be describing the nature of the human species more than the nature of the international system. If our hypothesis is correct, then evolutionary theory offers the following: (1) a novel ultimate cause of offensive realist behavior; (2) an extension of offensive realism to any domain in which humans compete for power; and (3) an explanation for why individual leaders themselves, and not just states, seek power. However, a key insight from evolution is that the primacy of self-help, power maximization, and outgroup fear does not necessarily condemn individuals or groups to competition and conflict; rather, these traits can in themselves give rise to cooperation and alliances.

Group violence, despite much study, remains enigmatic. Its forms are numerous, its proximate causes myriad, and the interrelation of its forms and proximate causes poorly understood. We review its evolution, including preadaptations and selected propensities, and its putative environmental and psychological triggers. We then reconsider one of its forms, ethnoreligious violence, in light of recent discoveries in the behavioral and brain sciences. We find ethnoreligious violence to be characterized by identity fusion and by manipulation of religious traditions, symbols, and systems. We conclude by examining the confluence of causes and characteristics before and during Yugoslavia's wars of disintegration.

Background. Institutions are hard to define and hard to study. Long prominent in political science have been two theories: Rational Choice Institutionalism (RCI) and Historical Institutionalism (HI). Arising from the life sciences is now a third: Evolutionary Institutionalism (EI). Comparative strengths and weaknesses of these three theories warrant review, and the value-to-be-added by expanding the third beyond Darwinian evolutionary theory deserves consideration.

Question. Should evolutionary institutionalism expand to accommodate new understanding in ecology, such as might apply to the emergence of stability, and in genetics, such as might apply to political behavior?

Methods. Core arguments are reviewed for each theory with more detailed exposition of the third, EI. Particular attention is paid to EI's gene-institution analogy; to variation, selection, and retention of institutional traits; to endogeneity and exogeneity; to agency and structure; and to ecosystem effects, institutional stability, and empirical limitations in behavioral genetics.

Findings. RCI, HI, and EI are distinct but complementary.

Conclusions. Institutional change, while amenable to rational-choice analysis and, retrospectively, to criticaljuncture and path-dependency analysis, is also, and importantly, ecological. Stability, like change, is an emergent property of institutions, which tend to stabilize after change in a manner analogous to allopatric speciation. EI is more than metaphorically biological in that institutional behaviors are driven by human behaviors whose evolution long preceded the appearance of institutions themselves.

A high capacity for visual perception distinguishes Homo sapiens from other primates. This human ability to detect social cues and retain visual records of social networks has been tested mostly with static facial images in laboratory settings. However, media consumption has become closely entangled with the way social life is navigated. Therefore, the study reported here tested demographic differences (gender and education) in visual information processing of social and nonsocial objects featured in audiovisual news content. Women recognized (accuracy) and recalled (salience) social images better than men. On the other hand, men were more skilled at recognizing, but not recalling, nonsocial images. Participants with lower educational levels recognized and recalled fewer images than individuals with higher educational levels. Interactions between demographic variables and time suggest that memory records for social images are more stable than those for nonsocial images. Memory may have survival-relevant importance, serving navigational functions that vary across environmental demands, resulting in differences across demographic groups.