The papers in this volume present varying approaches to human aggression, each from an evolutionary perspective. The evolutionary studies of aggression collected here all pursue aspects of patterns of response to environmental circumstances and consider explicitly how those circumstances shape the costs and benefits of behaving aggressively. All the authors understand various aspects of aggression as evolved adaptations but none believe that this implies we are doomed to continued violence, but rather that variation in aggression (...) has evolutionary roots. These papers reveal several similarities between human and nonhuman aggression, including our response to physical strength as an indicator of fighting ability, testosterone response to competition, a sensitivity to paternity, and baseline features of intergroup aggression in foragers and chimps. There is also one paper tackling the phylogeny of these traits. The many differences between human and nonhuman aggression are also pursued here. Topics here include the impact of modern weapons and extremes of wealth and power on both the costs and benefits of fighting, and the scale to which coercion can promote aggression that acts against a fighter’s own interests. Also the implications of large-scale human sociality are discussed. (shrink)

The relation between testosterone levels and aggressive behavior is well established. From an evolutionary viewpoint, testosterone can explain at least part of the sex differences found in aggressive behavior. This explanation, however, is mediated by factors such as prenatal testosterone levels and basal levels of cortisol. Especially regarding sex differences in aggression during adolescence, these mediators have great influence. Based on developmental brain structure research we argue that sex differences in aggression have a pre-pubertal origin and are maintained (...) during adolescence. Evidence of prenatal, adolescent, and adult levels of testosterone in relation to aggression taken together, support Archer's argument for sexual selection as the driver of sex differences in aggression. (shrink)

This book seeks to resolve an issue that has divided psychoanalysts and other scholars of aggression for decades, namely the nature of aggression. The work expands and unifies the Freudian drive-based explanation of aggression into contemporary psychoanalytic theory and practice and brings Freudian theory into the 21st Century.

Human psychology contains adaptations to deploy aggression as one solution to many distinct adaptive problems. These include expropriating resources, defending against incursions, establishing encroachment-deterring reputations, inflicting costs on rivals, ascending dominance hierarchies, dissuading partner defection, eliminating fitness-draining offspring, and obtaining new mates. Aggression is not a singular strategy. Comprehensive theories must identify the of multiple adaptations for aggression.

Using fractal analyses to study events allows us to capture the scale-independence of those events, that is, no matter at which level we study a phenomenon, we should get roughly the same results because events exhibit similar structure across scales. This is demonstrably true in mathematical fractals but is less assured in behavioral fractals. The current research directly tests the scale-independence hypothesis in the behavioral domain by exploring the fractal structure of aggression, a social phenomenon comprising events that span (...) temporal scales from minutes of face-to-face arguments to centuries of international armed conflicts. Using publicly available data, we examined the temporal fractal structure of four scales of aggression: wars, riots, violent crimes, and body movement during arguments. Our results lend mixed support to the scale-independence hypothesis and provide insight into the self-organization of human interactions. (shrink)

Both genetic and environmental factors have key roles in determining aggressive tendencies. In particular, reaction to stress appears to be an important factor in precipitating aggressive episodes and individuals may vary in their ability to cope with stressful environments depending on their genetic make up. Evidence from humans and primates indicates that adverse rearing conditions may interact with variants in stress and neurotransmitter pathway genes leading to antisocial and/or violent behaviour. Common alleles of some serotonin pathway genes, including those involved (...) in its degradation (monoamine oxidase A, MAOA), or its re‐uptake into pre‐synaptic neurones (serotonin transporter, SERT) have been shown to confer functional variation. Examination of the interaction between the alleles of such polymorphisms (in particular those affecting MAOA) and environmental stressors suggest that they may provide protection against, or increase sensitivity to, abusive upbringing; an observation that may explain part of the variability in developmental outcomes associated with maltreatment. BioEssays 29: 227–236, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

Archer provides seemingly compelling evidence for his claim that sexual selection explains sex differences in human aggression better than social role theory. I challenge Archer's interpretation of some of this evidence. I argue that the same evidence could be used to support the claim that what has been selected for is the ability to curb aggression and discuss implications for Archer's theory.

Our commentary focuses on the interaction between Grossmann's fearful ape hypothesis (FAH) and the human self-domestication hypothesis (HSDH), also taking into account language acquisition and evolution. Although there is considerable overlap between the two hypotheses, there are also some discrepancies, and our goal is to consider the extent to which HSDH can explain the phenomena identified by FAH without invoking fearfulness as directly adaptive.

This book explores the role of aggression in primate social systems and its implications for human behavior.

Darwin's and Freud's theories cohere in explaining human group conflict.

Darwin's and Freud's theories cohere in explaining human group conflict.

. Human ceremonial ritual is considered as an evolved behavior, one of the principal effects of which is the promotion of intragroup cohesion by decreasing or eliminating intragroup aggression. It is seen as a major determinant of what Victor Turner calls communitas in human social groups of varying extension. The frequent paradoxical effect of ritual's promoting extragroup aggression at the same time that it diminishes intragroup aggression is considered. A neuroevolutionary model of the development and (...) social effects of ritual behavior is presented, being derived from both ethology and recent neurophysiological studies in humans. (shrink)

In Studying Human Behavior, Helen E. Longino enters into the complexities of human behavioral research, a domain still dominated by the age-old debate of “nature versus nurture.” Rather than supporting one side or another or attempting..

Can exposure to media portrayals of human violence impact an individual’s ethical decision making at work? Ethical business failures can result in enormous financial losses to individuals, businesses, and society. We study how exposure to human violence—especially through media—can cause individuals to make less ethical decisions. We present three experiments, each showing a causal link between exposure to human violence and unethical business behavior, and show this relationship is mediated by an increase in individual hostility levels as (...) a result of exposure to violence. Using observational data, we then provide evidence suggesting that this relationship extends beyond the context of our experiments, showing that companies headquartered in locations marked by greater human violence are more likely to fraudulently misstate their financial statements and exhibit more aggressive financial reporting. Combined, our results suggest that exposure to human violence has significant and real effects on an individual’s ethical decision making. (shrink)

Intraspecific aggression (IA), in service to dominance, has far deeper roots in animal behavior and human evolution than does predation. The reinforcing properties of such aggression are most likely to be a major source of human cruelty.

Worldwide there are substantial differences within and between countries in aggression and violence. Although there are various exceptions, a general rule is that aggression and violence increase as one moves closer to the equator, which suggests the important role of climate differences. While this pattern is robust, theoretical explanations for these large differences in aggression and violence within countries and around the world are lacking. Most extant explanations focus on the influence of average temperature as a factor (...) that triggers aggression, or the notion that warm temperature allows for more social interaction situations in which aggression is likely to unfold. We propose a new model, CLimate, Aggression, and Self-control in Humans, that helps us to understand differences within and between countries in aggression and violence in terms of differences in climate. Lower temperatures, and especially larger degrees of seasonal variation in climate, call for individuals and groups to adopt a slower life history strategy, a greater focus on the future, and a stronger focus on self-control. The CLASH model further outlines that slow life strategy, future orientation, and strong self-control are important determinants of inhibiting aggression and violence. We also discuss how CLASH differs from other recently developed models that emphasize climate differences for understanding conflict. We conclude by discussing the theoretical and societal importance of climate in shaping individual and societal differences in aggression and violence. (shrink)

The evolutionary origins of deception and its functional role in our species is a major focus of research in the science of human origins. Several hypotheses have been proposed for its evolution, often packaged under either the Social Brain Hypothesis, which emphasizes the role that the evolution of our social systems may have played in scaffolding our cognitive traits, and the Foraging Brain Hypothesis, which emphasizes how changes in the human dietary niche were met with subsequent changes in (...) cognition to facilitate foraging of difficult-to-acquire foods. Despite substantive overlap, these hypotheses are often presented as competing schools of thought, and there have been few explicitly proposed theoretical links unifying the two. Utilizing cross-cultural data gathered from the Human Relations Area Files (HRAF), we identify numerous (n = 357) examples of the application of deception toward prey across 145 cultures. By comparing similar behaviors in nonhuman animals that utilize a hunting strategy known as aggressive mimicry, we suggest a potential pathway through which the evolution of deception may have taken place. Rather than deception evolving as a tactic for deceiving conspecifics, we suggest social applications of deception in humans could have evolved from an original context of directing these behaviors toward prey. We discuss this framework with regard to the evolution of other mental traits, including language, Theory of Mind, and empathy. (shrink)

I argue that the magnitude and nature of sex differences in aggression, their development, causation, and variability, can be better explained by sexual selection than by the alternative biosocial version of social role theory. Thus, sex differences in physical aggression increase with the degree of risk, occur early in life, peak in young adulthood, and are likely to be mediated by greater male impulsiveness, and greater female fear of physical danger. Male variability in physical aggression is consistent (...) with an alternative life history perspective, and context-dependent variability with responses to reproductive competition, although some variability follows the internal and external influences of social roles. Other sex differences, in variance in reproductive output, threat displays, size and strength, maturation rates, and mortality and conception rates, all indicate that male aggression is part of a sexually selected adaptive complex. Physical aggression between partners can be explained using different evolutionary principles, arising from the conflicts of interest between males and females entering a reproductive alliance, combined with variability following differences in societal gender roles. In this case, social roles are particularly important since they enable both the relatively equality in physical aggression between partners from Western nations, and the considerable cross-national variability, to be explained. (shrink)

This paper highlights the evolutionary biological epistemology in Freud psychoanalytic theory. The concepts of aggressive and sexual drives are fulcrum of the psychoanalytic epistemological system, concerning the motivational/emotional roots of mental functioning. These biological roots of mental functioning, especially with regard to aggressive drive, have gradually faded away from psychoanalytic epistemology, as we show in the paper. Currently, however, Neurosciences, and in particular Affective Neuroscience (Panksepp 1998), can contribute to increase the knowledge of the biological roots of human mental (...) functioning. The motivational/emotional systems studied by Affective Neuroscience can give a new epistemological foundation to the aggressive drive concept in psychoanalytic theory. Over the course of human evolution motivational/emotional systems have assumed the role of organizers of social relationships and also of mental functioning. In this regard, among the various types of aggression (ANGER in Panksepp taxonomy 1998), that we consider in our paper is inter-male aggression, also named Dominance motivational/emotional system, which regulates social interactions between sexually mature adults. This type of aggression acts in complementary connection with FEAR motivational/emotional system, that regulate Submissive behaviour and Social defeat, the latter one of the more important stressors. The interaction between aggressiion and FEAR motivational/emotional systems gives rise to Agonistic behaviour or Dominance/Submission motivational/emotional system, as we propose in our paper. There is now a large literature that identifies in the dynamic of Agonistic behaviour one of the main factors of mental illness. When social interactions activate the Agonistic behavior, the subject can perceive himself as "destined to victory" or "destined to defeat", activating either behaviours and emotions connected to the Involuntary Defeat Strategy or Involuntary Dominant Strategy, that we can find in many types of mental disorders, e.g. mood disorders or anxiety disorders. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Reviewed by:Studying Human Behavior: How Scientists Investigate Aggression and Sexuality by Helen LonginoRebecca KuklaReview: Helen Longino, Studying Human Behavior: How Scientists Investigate Aggression and Sexuality, University of Chicago Press, 2013In Studying Human Behavior: How Scientists Investigate Aggression and Sexuality, Helen Longino meticulously examines a wide variety of research programs devoted to studying human behavior, specifically aggression and sexual orientation. She teases (...) apart the methodologies of the various approaches, examining their epistemic structure, the assumptions they must hold fixed, the research questions they enable and those they necessarily occlude, their underlying ontologies, the interests that motivate them, the ideological investments they help buttress, and the practical and political uses they serve. By the end of the book she has made clear that the so-called ‘nature-nurture’ debates invoke a hopelessly simplistic and distorting dualism when it comes to any interesting question about the etiology of a behavior. This is a readable, informative, rigorous, and elegantly organized new work from a leading scholar who has had a major hand in turning the interplay among science, ethics, and social interests into a topic of rigorous philosophical study.In the first part of the book, Longino devotes a chapter or substantial section to each major methodological approach to studying aggression and sexual orientation, including (using her labels): quantitative behavioral genetics, social-environmental approaches, molecular behavioral genetics, neurobiological approaches, and several ‘integrative’ approaches (such as developmental systems theory) that focus on the interactions and dynamics between causal factors over time rather than trying to isolate one causal contribution. She also briefly discusses human ecology, which takes the unit of study to be the behavior of a population, studied in its material environment, rather than the behavior of an individual.Longino shows elegantly how each of these research programs is equipped to reveal certain specific kinds of truths about behavior, while making other important dimensions of the phenomena invisible. Many of her examples are technical and detailed, but I can recap a few relatively simple and powerful examples: (1) Behavioral researchers have no shared understanding of what an ‘environment’ is or which features of it we need [End Page E-97] to measure. Whatever operationalization of ‘environment’ is used within a study or set of studies, this operationalization is not itself scientifically validated, but merely presupposed (33). Thus how much of a behavior shows up in a study as due to the ‘environment’ depends on just what we measure. On the behavioral genetic approach this will include everything other than genes, but on, say, the neurobiological approach this will be everything other than neural structure. But these are quite different senses of ‘environment’ with different scopes, and there’s no good reason to think they are easily commensurable. (2) ‘GxExN’ researchers use techniques to study the etiology of behavior that were developed expressly for studying disorders (112). This work thus presupposes that we can understand whatever behavior is under study on the disorder model, and will yield no well-formed results to the extent that this model does not fit. But it is at best non-obvious that a disorder model is unproblematic when it comes to aggression or—especially!—sexual orientation. (3) Most of the research programs Longino covers treat the behaving individual as the unit of analysis and study, as opposed to, for example, human ecologists’ focus on whole populations. But as she demonstrates, this affects what kinds of causes we can study, because patterns at the population level may not be detectable using the kinds of measures that can be manipulated at the individual level. Furthermore, some kinds of behaviors may require more than one participant to exist at all; for instance, the very same thing that counts as an aggressive act within one interaction may be a peaceful act in another (175).Longino does a lovely job of showing what sorts of social interests are served and buttressed by which kinds of research. For example, social-environmental approaches will, in virtue of their methodology, focus on social factors that are manipulable, and this makes them particularly amenable to generating suggestions for social interventions. Such research thus better serves the ends of those who are looking to implement... (shrink)

This first part of a two‐part article illustrates how research in evolutionary biology and psychology illuminates questions arising in philosophy—specifically questions about the origins of severe, systemic aggression that arise in the mimetic theory of René Girard. Part I looks at: (i) how old the systemic practice of severe aggression is, (ii) how much results from humanity's mimetic/social and competitive nature and how much from ecological, resource, and cultural conditions, and (iii) if ecological and cultural conditions are important, (...) might we adapt them toward greater cooperativity today? After briefly reviewing mimetic theory, the article looks at evolutionary psychology and biology, including fossil and archeological evidence. Findings suggest that severe, systemic aggression might be relatively recent and that its occurrence depends on ecological/resource/socioeconomic conditions additional to our mimetic/social nature. Thus, distinguishing the conditions that prod aggression from those that support pro‐social behavior might aid us in structuring society today. (shrink)

Variability of aggression: human aggressive behavior varies on a number of dimensions. We argue that this variability is best understood through an interdisciplinary evolutionary approach.

Parallels in anatomy between humans and domesticated mammals suggest that for the last 300,000 years, Homo sapiens has experienced more intense selection against the propensity for reactive aggression than any other species of Homo. Selection against reactive aggression, a process that can also be called self-domestication, would help explain various physiological, behavioral and cognitive features of humans, including the unique system of egalitarian male hierarchy in mobile hunter-gatherers. Here I review nine leading proposals that could potentially explain why (...) self-domestication occurred in H. sapiens, whether by selecting in favor of cooperation and tolerance or by selecting against aggressiveness. To account for the domestication syndrome, proposals must explain what led to a decline in fitness of highly aggressive males, and why the explanatory factor applies only to H. sapiens rather than to other species of Homo. The proposed explanations invoke genetic group selection; group-structured culture selection (also known as cultural group selection); social selection by female mate choice; social selection by male partner choice; increased self-control; cooperative breeding; high population density; use of lethal weapons; and language-based conspiracy. Most proposals face difficulties in accounting for the origins and/or maintenance of self-domestication. I conclude that the evolution of language-based conspiracy, which is a form of collective intentionality, was the key factor initiating and maintaining self-domestication in H. sapiens, because it is the most convincing mechanism for explaining the selective pressure against individually powerful fighters. Sophisticated language enabled males of low fighting prowess to coordinate in executing physically aggressive and domineering alpha males. This system is known today as a leveling mechanism in small-scale societies. Group-structured culture selection possibly accelerated the process. (shrink)

Male aggression against females in primates, including humans, often functions to control female sexuality to the male’s reproductive advantage. A comparative, evolutionary perspective is used to generate several hypotheses to help to explain cross-cultural variation in the frequency of male aggression against women. Variables considered include protection of women by kin, male-male alliances and male strategies for guarding mates and obtaining adulterous matings, and male resource control. The relationships between male aggression against women and gender ideologies, male (...) domination of women, and female sexuality are also considered. (shrink)

Chimpanzee and hunter-gatherer intergroup aggression differ in important ways, including humans having the ability to form peaceful relationships and alliances among groups. This paper nevertheless evaluates the hypothesis that intergroup aggression evolved according to the same functional principles in the two species—selection favoring a tendency to kill members of neighboring groups when killing could be carried out safely. According to this idea chimpanzees and humans are equally risk-averse when fighting. When self-sacrificial war practices are found in humans, therefore, (...) they result from cultural systems of reward, punishment, and coercion rather than evolved adaptations to greater risk-taking. To test this “chimpanzee model,” we review intergroup fighting in chimpanzees and nomadic hunter-gatherers living with other nomadic hunter-gatherers as neighbors. Whether humans have evolved specific psychological adaptations for war is unknown, but current evidence suggests that the chimpanzee model is an appropriate starting point for analyzing the biological and cultural evolution of warfare. (shrink)

We propose that human self-domestication favored the emergence of a less aggressive phenotype in our species, more precisely phenotype prone to replace (reactive) physical aggression with verbal aggression. In turn, the (gradual) transition to verbal aggression and to more sophisticated forms of verbal behavior favored self-domestication, with the two processes engaged in a reinforcing feedback loop, considering that verbal behavior entails not only less violence and better survival, but also more opportunities to interact longer and socialize (...) with more conspecifics, ultimately enabling the emergence of more complex forms of language. Whereas in the case of self-domestication sexual selection has been proposed to work against physical aggression traits, in the case of verbal insult the selection has been proposed to work in favor of verbal aggression. The tension between these two seemingly opposing forces gets resolved/alleviated by a tendency to replace physical aggression with verbal aggression, and with verbal behavior more generally. This also helps solve the paradox of the Self Domestication Hypothesis regarding aggression, more precisely why aggression in humans has been reduced only when it comes to reactive aggression, but not when it comes to proactive aggression, the latter exhibiting an increase with the advent of modern language. We postulate that this feedback loop was particularly important during the time period before 50 kya, arguably between 200 kya and 50 kya, when humans were not fully modern, neither in terms of their skull/brain morphology and their behavior/culture, nor in terms of their self-domestication. The novelty of our approach lies (i) in giving an active role to early forms of language in interacting with self-domestication processes; (ii) in providing specific linguistic details and functions of this early stage of grammar (including insult and humor); (iii) in supplying neurobiological, ontogenetic, and clinical evidence of a link between (reactive) aggression and (reactive) verbal behavior; (iv) in identifying a variety of proxies of the earlier stages in evolution among cognitive disorders; and (v) in identifying specific points of contact and mutual reinforcement between these two processes (self-domestication and early language evolution), including reduction in physical aggression and stress/tension, as well as sexual selection. (shrink)

Sex differences in aggressive behavior are probably adaptive but the costs and benefits of risky aggression to women and men may be different from those suggested in Campbell's target article. Moreover, sex differences are more likely to reflect differences in the costs of aggression to females and males rather than differences in its benefits.

Archer presents a traditional view of intrasexual competition. Knowledge of a species' social structure provides a more complete picture. Human males compete against individuals with whom they may cooperate later in inter-group aggression. By contrast, females compete against individuals for a mate's continued support. Females' aggression may aim at eliminating the competition, whereas males simply may attempt to dominate others.

Human aggression has two important dimensions: within-group aggression and between-group aggression. Archer offers an excellent treatment of the former only. A full explanation of sex differences in aggression will fail without accounting for our history of inter-group aggression, which has deep evolutionary roots and specific psychological adaptations. The causes and consequences of inter-group aggression are dramatically different for males and females.

The ultimate causes of sex differences in human aggressive behavior can lie mainly in evolved, inherited mechanisms that differ by sex or mainly in the differing placement of women and men in the social structure. The present commentary contrasts Campbell's evolutionary interpretation of aggression sex differences with a social structural interpretation that encompasses a wider range of phenomena.

Despite mounting evidence that abusive supervision triggers interpersonal aggression, much remains unknown regarding the underlying causal mechanisms within this relationship. We explore the role of turnover intentions as a mediator in the relationship between abusive supervision and subsequent supervisor-rated interpersonal aggression. We use a sample of 324 supervisor–subordinate dyads from nine organizations and find support for this mediation effect. Furthermore, we find that power-distance orientation and perceived human resource support climate, as important boundary conditions, independently interact with (...) abusive supervision to weaken this positive impact on turnover intentions, thereby reducing interpersonal aggression. We also find via turnover intentions that abusive supervision intensifies interpersonal aggression among high power-distance-oriented individuals when the HR support climate is perceived to be low. Theoretical and practical implications are discussed. (shrink)

ABSTRACT The word, aggression, refers in general usage to unjustified attack, and any serious writer who uses it extensively in some figurative or newly‐coined technical sense should leave his meaning in no doubt. Unfortunately some ethological writers fail to do this and deceive themselves into the bargain. They somewhat naively claim to find aggression built into the fundamental nature of animals, a kind of instinct which cannot be resisted, indeed which must figure in their social cohesion. If the (...) word really retains the moral connotation which I have indicated, then much animal biology is vitiated. Not only are animals misjudged, but, since conclusions are then applied to our human selves, we too are misjudged and recommended to adopt false moral principles. It is possible that ensuing armchair pseudo‐cures may be responsible for a real increase in human violence. (shrink)

Theological anthropology can be enriched by paying attention to insights into human behavior taken from sociobiology. The capacity for reflective self‐consciousness enables the human animal to respond to basic instincts and drives in unprecedented ways. Humans follow gender‐specific sexual strategies, display aggressive behavior, and respond to physical pain as do other animals. Yet human beings have the intellectual ability to express these tendencies uniquely in either destructive or constructive ways. The human being, unlike any other animal, (...) must reckon with sexual ethics, the problem of violence, and the meaning of suffering. In developing the basic concepts of theological anthropology—good creation, natural evil, fall, sin, and image of God—sociobiological research can lead to more adequate understanding of the human. (shrink)

According to I3 Theory, individuals enact aggressive behaviors when (a) instigating triggers are severe, (b) impelling forces are strong, and/or (c) inhibiting forces are weak. Archer's analysis of human sex differences in aggression could be bolstered by a careful analysis of male-female discrepancies in reactivity (or exposure) to instigating triggers, proneness toward impelling forces, and/or proneness toward inhibiting forces.

It has sometimes been said that it is useless to try to prevent wars since man has an ineradicable combative instinct. The term instinct is very ambiguous in its application to humans, and it may be interesting to see what occurs amongst the insects, many of whose species show the highest development of instinctive behaviour.Many insect species are predatory, but if they depend on other distinct species, the relation is analogous to hunting or to a crude form of agriculture. Aggressive (...) behaviour to be comparable with war must concern the different members of one species. There are many laboratory experiments which illustrate the effects of competition when a population begins to exceed the capacity of its food supply. In Flour beetles, for instance, the adult beetles and the larvae eat any egg or pupae which they happen to meet in their ceaseless burrowing through the flour. There is thus a fixed population density at which eggs are eaten as fast as they are laid. In Grain weevils, the effect of crowding is to reduce the rate at which eggs are laid by the females who appear to suffer from overstimulation when crowded. Other effects, usually harmful, may be produced by the accumulation of the products of respiration or of digestion. Finally, if the food supply is too small, there will be death from starvation. If, for instance, too many blowfly eggs are added to a piece of meat, the flies produced will either be small, weak, and infertile or, if the excess has been too great, the larvae may all starve when half grown. Thus, a piece of meat which could have produced 100 normal flies may produce none at all if a tenfold excess of eggs is laid on it. (shrink)

In this volume, the third in his trilogy on the philosophical and legal aspects of war and conflict, Larry May locates a normative grounding for the crime of aggression - the only one of the three crimes charged at Nuremberg that is not currently being prosecuted - that is similar to that for crimes against humanity and war crimes. He considers cases from the Nuremberg trials, philosophical debates in the Just War tradition, and more recent debates about the International (...) Criminal Court, as well as the hard cases of humanitarian intervention and terrorist aggression. His thesis refutes the traditional understanding of aggression. At Nuremberg, crimes against humanity charges were only pursued if the defendant also engaged in the crime of aggression. May argues for a reversal of this position, contending that aggression charges should be pursued only if the defendant's acts involve serious human rights violations. (shrink)

Coalitions and alliances are core aspects of human behavior. All societies recognize alliances among communities, usually based in part on kinship and marriage. Aggression between groups is ubiquitous, often deadly, fueled by revenge, and can have devastating effects on general human welfare. Given its significance, it is surprising how little we know about the neurobiological and hormonal mechanisms that underpin human coalitionary behavior. Here we first briefly review a model of human coalitionary behavior based on (...) a process of runaway social selection. We then present several exploratory analyses of neuroendocrine responses to coalitionary social events in a rural Dominican community, with the objective of understanding differences between in-group and out-group competition in adult and adolescent males. Our analyses indicate: (1) adult and adolescent males do not elevate testosterone when they defeat their friends, but they do elevate testosterone when they defeat outsiders; (2) pre-competition testosterone and cortisol levels are negatively associated with strength of coalitionary ties; and (3) adult males usually elevate testosterone when interacting with adult women who are potential mates, but in a striking reversal, they have lower testosterone if the woman is a conjugal partner of a close friend. These naturalistic studies hint that reciprocity, dampening of aggression, and competition among friends and allies may be biologically embedded in unique ways among humans. (shrink)

Quantitative genetic studies of human aggressive behavior only partly support the claim of social role theory that individual differences in aggressive behavior are learnt rather than innate. As to its heritable component, future studies on the genetic architecture of aggressive behavior across different contexts could shed more light on the evolutionary origins of male-female versus male-male aggression.