Aggression in men. Social roles or evolutionary roots?


In almost every society men are the ones who are overwhelmingly involved in wars, in all kinds of intergroup aggressions and intragroup homicide; they mobilize themselves in armies of violent fans, in criminal gangs, in bands of thugs, etc. These observations are as old as the world and have allowed us to create a clear distinction between male and female sexes regarding their predisposition to violence. Wars are a biosocial product of men and a field for male’s manifestation [Goldstein, 2001]. The same thing is true of crime and cruelty, which are closely linked to masculinity.

Canadian evolutionary psychologists Martin Daly and Margo Wilson, who specialize in studying the homicide phenomenon, have analyzed 35 homicide data sets from 14 countries, including some from primitive societies and some from different eras. Among these societies men committed homocide, on average, 26 times more frequently than women [Daly, Wilson, 1994]. Also, familicides (the killing of family members) are committed mostly by men. Some data have shown that men were involved in more than 90 percent of cases [Wilson, Daly, 1997, p. 160].

Men are also, in 70 percent of cases, the victims of homicides. In some societies, this percentage jumps to over 90 percent [Daly, Wilson, 1988; Berkowitz, 1993, p. 274, apud Buss, Duntley, 2002].

In the Russian Federation, in 1996, 86.6 percent of all serious crimes were committed by men. In the U.S., in 2004, 85 percent of total serious crimes were committed by men. Ninety-two percent of serial killers from the U.S. are men [1]. This statistical report is valid for most countries, regardless of their geographical location or size. In Republic of Moldova, for example, about 90 percent of crimes are committed by men [2].

A study in Switzerland, on prisoners convicted for violent offence, showed that 7.9% of the sample were female. Significant gender differences were found: Female offenders were more likely to be married, less educated, to have suffered from adverse childhood experiences and to be in poor mental health [Rossegger et al., 2009]. So women are a minority, an exception in violent offence statistics.

Let us analyze another dimension of violence – cruelty and animal abuse. One of the studies that approached this issue found the following male-to-female ratio, regarding violence to animals: beatings – 38 to 1, shooting – 16 to 1, torture – 20 to 1, burning – 17 to 1 [Gerbasi, 2004].

Why are men more aggressive than women? Several theories have been proposed, trying to explain this phenomenon, most of them being from social psychological theories. One of the most popular theories belongs to American social psychologist Leonard Berkowitz. According to him, men and women are educated, traditionally, to carry out different social roles. Berkowitz uses the following reasoning for his theory: Think of all the ways in which modern Western society teaches children that fighting is more suitable for men than to women. Folk literature and the media constantly present men, and not women, fighting. Parents buy toy guns for boys and dolls for girls. Parents are more willing to endorse and encourage the aggressive behavior of boys, and not of girls. Again and again, directly and indirectly, minors learn that men are aggressive, and women not [Berkowitz, 1993, p. 395].

The theory of “social roles” has created a new paradigm in gender policies and marks even today the way in which many civic and preschool education strategies are developed; it is presumed that girls and boys shall be educated and treated alike, non-discriminatory, and even the behavioral differences between them will disappear. However, although it contains in itself a good dose of truth (boys and girls were, traditionally, part of a different education), Berkowitz’s theory about learned social roles was subject to several critics, who have shown its vulnerabilities.

First of all, Berkowitz’s theory mirrored more the Western culture, but didn’t take into account the realities from other cultures (without cinema, literature, media, toy stores), where the behavioral patterns of boys still greatly differ from that of girls. It was noted, among other things, that homicides in North America (where it seems that the media fosters intense social roles) are marked by sex differences in a lesser degree than in many other societies [Daly, Wilson, 1989, p. 101-102, apud Buss, Duntley, 2002].

Second, it’s not the parents that impose behavioral styles to their children, but their reaction at the latter’s requests; toy guns are bought to boys and dolls to girls because these are usually the children’s preferences (in part genetically predetermined). And as parents respond to children’s preformed wishes, so do media offer a content which corresponds to behavioral patterns already existing on social level [Hoyenga, Hoyenga, 1993].

Let’s keep in mind that some experiments have confirmed the strong predilection of boys for toys considered “masculine” (various mechanisms, trucks), while girls are more flexible, spending relatively equal amounts of time playing with boy-favored toys and with more traditionally “feminine” toys such as dolls. Was made the connection between the body’s hormonal status (androgen) and respective preferences [Berenbaum, Hines, 1992]. Also, it was considered that these propensities are somewhat stereotyped, that boys face greater societal discouragement when they play with “girl toys” than girls do in the reverse situation [3].

But an ingenious experiment performed on macaca-rhesus (Macaca mulatta) demonstrated that we are dealing with something deeper than mere stereotypes. Faced with the choice, male rhesus monkeys also clearly preferred ”masculine” toys. Obviously, in case of these monkeys, cannot talk about the influence of any sexist stereotype or social pressure [Hassett et al., 2008]. It is an instinctual behavior pattern.

It is more than that. American primatologists Sonya Kahlenberg and Richard Wrangham have observed an interesting phenomenon in juvenile chimpanzees. They, in particular females, carries a small stick for hours, while eating, walking or resting. Researchers have assumed that these juvenile females practice a form of play-mothering. Need to mention, that they observed this behavior within a single population, and it is possible that this is a isolated behaviour, culturally formed and transmitted only in this community of chimpanzees [Kahlenberg, Wrangham, 2010].

Overall, there are reasons to inference that sexually differentiated object preferences (inclusive dimorphic toy preferences in children) arose early in human evolution, prior to the emergence of a distinct hominid lineage. This implies that sexually dimorphic preferences for features may have evolved from differential selection pressures based on the different behavioral roles of males and females. Only later intervened social and cultural factors [Alexander, Hines, 2002]. That is why the most apposite conclusion from all these data is that sex differences in children’s toy preferences appear to be multiply determined; innate influences are augmented by social encouragement, particularly in boys [Hines, Alexander, 2008].

Regarding the manifestation of aggression in humans, biological side is much stronger. Controversy about social or biological origins of male aggressiveness was partially solved by a research carried out in 2007 on the babies. Contrary to the differential socialization hypothesis, already at the age of 17 months boys show a higher proportion (5%) of acts of physical aggression than girls (1%). These behavioral differences appears before any social influences have affected it in some way [Baillargeon et al., 2007]. So, inner causes of instinctual nature increased male aggression from the earlier stages of development.

According to mothers reports, boys engaged in more physical aggression than girls. In contrast, indirect aggression was more common among girls, especially during elementary school (6–11 years old). When adolescents (12–15 years old) were asked to rate their own physical and indirect aggression, physical aggression was much higher for boys, but indirect aggression was equivalent for both boys and girls [Archer, Côté, 2005; Côté, 2007].

Boys also maintain a stronger propensity toward physical aggression than do girls. In the NLSCY sample, 62% of the children following a high stable trajectory of aggression from ages 2 to 11 were boys. Conversely, more of the children on the low trajectory were girls (56%) [Côté et al., 2006, apud Tremblay et al., 2008, p. 11-12].

In addition, was found that when witness their parents quarrels and physical aggression, children react differently, according to gender. Girls keep their feelings inside and withdraw while boys tend to project their emotions and their aggression outward [Holmes et al., 2014].

Of course, in the families with high levels of gender inequality, the difference in aggression between boys and girls will be higher than in families with low levels of gender inequality. However, this effect is small in comparison to the direct effect of a child’s biological sex [Nivette et al., 2014]. In other words, the biological impact is still stronger than the effect of the social factors.

Also important in this regard are the findings of social psychologists who have noted that the social emancipation of women in recent decades has barely influenced or enhanced the expressiveness of aggressive behavior in women, which is additional proof that the higher degree of masculine aggressiveness is, first of all, due to genetic factors. Sex differences predetermine, on a genetic level, the differences in aggressive behavior [Wilson, Herrnstein, 1985].

According to American psychologist Anne Campbell, who is concerned with sex differences in aggression with special emphasis upon female aggression, there are pronounced differences in fear between male and females, especially of physical danger. In other words, women are in general more easily frightened. In women, the amygdala (the brain structure responsible for the emotional response) show heightened reactivity to threatening stimuli. Campbell highlights that, from an evolutionary perspective, the intensity of female aggression is constrained by the greater centrality of mothers, rather than fathers, to offspring survival. That explains women’s lower involvement in a range of risky activities such as extreme sports, dangerous driving and criminal activities. This does not mean, however that women aren’t actively implementing in other competitive strategies [Campbell, 2006, 2013].

In a study on the real magnitude of psychological sex differences, a size that came out clearly in evidence was namely that related to the manifestation of aggression. For men greater physical aggression is typical, while women use so-called indirect aggression (without displaying direct hostility) [Del Giudice, 2009, p. 273-274]. Earlier studies had shown that it’s specific for women to use verbal aggression in intrasexual competition (between women) and there rarely are cases of physical assault; practically, women use mainly language in competitive strategies [Buss, Dedden, 1990, apud Fitzgerald, Whitaker, 2009, p. 469].

It is interesting that although men and women have equal opportunities to behave aggressively in online communication (cyberbullying), it was found that males were slightly more likely to cyberbully than females, and males showed higher levels of cyberbullying during later adolescence than females [Barlett, Coyne, 2014].

It is true that in domestic violence exist a relatively high rate of women who assaulting family members, children, spouses. They can exercise even a physical aggression. A sociological study in the UK revealed, surprisingly, that in reality, about 40% victims of intimate partner violence are men. Most often, such cases remain unreported [3]. Other studies have confirmed the high degree of aggression which women can demonstrate particular in relation to their life partner, from the desire to have control upon them. So, women also can be classed as “intimate buy diflucan online terrorists” [Bates et al., 2014].

Other authors think that women are violent when they want to separate from partner or in process of defending themselves from male bullying and abuse [Flynn, 1990]. So, women defend himself, not attack.The nature of this aspect of aggressive behavior yet must to be disclosed and explained. We can interpret it as an exception that proves the rule; in the overwhelming majority of other dimensions of human behavior, men are who manifest violent, especially if we consider physical violence.

Most relevant in explaining the genesis of aggression in men proved to be the approaches from an evolutionary perspective. Thus, the fact that men are more aggressive and stronger than women can be explained through intrasexual competition (between males). Men have inherited these skills from our evolutionary ancestors, because, in general, in the living world, gaining a higher hierarchical status, resources, protecting the family and obtaining competitive advantages in conquering women involves increased physical contest and increased aggressiveness [Buss, Duntley, 2006; Gat, 2010]. Similarly, in many animal species, including primates, males have the biological role of being guardians of the territory and of banishing the intruders or of protecting the group from predators, and these functions imply that males exhibit a higher level of aggression than females [Wilson, 1975].

The fact that males are more aggressive and more violent is reflected by their anatomy itself; in many animals species they are heavier, more muscular, better armed with means of attack and defense. In humans, for example, the arms of men are, on average, 75% more muscular than those of women; and the top of a male body is 90% more stronger that the top of a female body [Bohannon, 1997; Abe et al., 2003, apud Goetz, 2010, p. 16].

One study has shown that the very strongest female athletes are barely above the median of hand-grip strength for men. The top 75th percentile of female athletes are below the bottom 25th percentile of men (ses the graphic below). In general, the more muscular men and women are, the stronger they are. But even the most muscular women can barely beat the least muscular men [Leyk et al., 2007].

Men Are Stronger Than Women

Also, men are taller, they have denser and heavier bones, their jaw is more massive, their reaction time is shorter, their visual acuity is better, their muscle/fat ratio is greater, their heart is bulkier, their percentage of hemoglobin is higher, their skin is thicker, their lungs bigger, their resistance to dehydration is higher etc. In other words, from all points of view, men are more suited for battle than women, and these skills are native, they were selected and evolutionary polished [Sell et al., 2012, p. 33]. In men the nose is 10% higher than in women, as an adaptation for a better supply of oxygen to the male body muscles; differences in the development of the nose are already observable in puberty [Holton et al., 2014].

Gender differences exist even in the neurological development. In particular, the amygdala, where emotions generally arise, develops about eighteen months sooner in girls than in boys in early adolescence. In recent years, a large number of studies appear on differences in brain function in men and women [5], [6], [Jensen, Nutt, 2015].

Men also have a specific hormonal status; testosterone, for example, is directly responsible for inducing a competitive and even criminal behavior. According to Evolutionary Neuroandrogetic Theory, male sex hormones (androgens) are correlated with the increased ability of males to acquire resources, hierarchical position and sexual partners [Ellis, 2003, 2004].

All these anatomical, hormonal, behavioral and evolutional factors demonstrate the biological, instinctual inclination of men in being more combative. Therefore, on individual and social level, men are involved in acts of violence and crime. The social environment only cultivates and points out these predispositions towards fighting and aggression.

© Dorian Furtuna, ethologist


1. …? ??????????? ????????? ? ???????? // ??????? ?.?.”?????????? ???????????? ????????”. 2008 /
2. Statistica gender // Biroul Na?ional de Statistic? al Republicii Moldova /
3. Born This Way? Gender-Based Toy Preferences in Primates // AnimalWise. 01.26.2012 /
4. More than 40% of domestic violence victims are male, report reveals. Campaign group Parity claims assaults by wives and girlfriends are often ignored by police and media // by Denis Campbell. The Observer. Sunday 5 September 2010 /
5. Teen girls have different brains: Gender, neuroscience and the truth about adolescence. It’s indisputably true that in adolescence there are real differences in some brain functions with males, females // Dr. Frances E. Jensen and Amy Ellis Nutt. Salon. Saturday, Jan 3, 2015 /
6. Neuroscience of sex differences //

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