Where Does Human Violent Behavior Come From?

Comparing Human vs Animal Violent Behavior: Not Motivated by Need for Food

Introduction

People don’t usually eat or kill each other for survival. Yet, recent arbitrary killings, such as the tragic death of a young immigrant on a train, a political activist at a university, and the beheading of a motel manager over a workplace dispute, have made us question societal norms. These events prompt us to wonder about the origins of human violence. In contrast, killings in the animal kingdom that are not motivated by the need for food are rare but offer vital insights into the evolutionary, natural, and social drivers of violence.

This article explores cases of non-food killings among animals, including primates, cetaceans, carnivores, birds, and small mammals. It draws parallels to human acts of violence. These comparisons suggest that motives such as territoriality, reproductive advantage, dominance, and competition reduction are shared across multiple species. However, human behavior is layered and often amplified by additional social, cultural, and psychological complexities.

Orca attacking porpoises

Over the past month, several killings in the United States have gained national attention due to their victims, circumstances, and public impact. On September 10, 2025, conservative activist Charlie Kirk, co-founder of Turning Point USA, was shot and killed while speaking at Utah Valley University. This killing has been described as a political assassination, sparking heated debates about political violence in America. Around the same time, Chandra Mouli Nagamallaiah, an Indian-American motel manager in Dallas, was beheaded in front of co-workers after a workplace dispute. The brutality of this killing shocked the public and received extensive national coverage.

Earlier, on August 22, 2025, Iryna Zarutska, a Ukrainian refugee living in Charlotte, North Carolina, was stabbed to death on a light rail train platform. Her death became high-profile not only because of its public setting but also because she was a refugee who had fled the war in Ukraine, drawing both national and international coverage. Collectively, these cases represent some of the most prominent high-profile killings in the U.S. over the last month, each sparking discussions about political violence, workplace safety, and public security.

Comparative Analysis of Non-Food Killings

Across species, killings not motivated by food often arise from underlying drives such as dominance, reproductive advantage, or competition reduction. For instance, chimpanzees engage in coordinated raids on neighboring groups to expand territory and assert dominance (Wrangham, 2019). This behavior parallels human warfare and gang violence, where political, ethnic, or resource-driven motives fuel collective aggression. Similarly, lions and leopards commit infanticide by killing rival offspring to increase reproductive opportunities. This behavior mirrors human cases of step-parental violence or targeted killings aimed at eliminating rival family lines or consolidating power (Hrdy, 1979; Daly & Wilson, 1988).

Dolphins and orcas sometimes kill calves or smaller marine mammals without consuming them. These behaviors are attributed to play, practice, or displays of dominance. This is strikingly similar to human acts of violence committed for thrill, spectacle, or training. Examples include violent sports, hazing, or military exercises where aggression is ritualized rather than survival-driven (Pinker, 2011; Palagi et al., 2014). Likewise, crows, ravens, and meerkats may attack the young of competitors to reduce future rivalry. This reflects the human tendency toward career sabotage or political maneuvering designed to weaken opponents before they become threats.

In humans, these animal parallels are compounded by cultural, ideological, and social layers. Religious killings, for instance, extend the evolutionary drive of ingroup loyalty and outgroup hostility into the domain of sacred identities, making violence appear divinely sanctioned (Juergensmeyer, 2017). Political assassinations highlight another human extension—where killings are framed as serving ideological or nationalistic causes, much like territorial raids in chimpanzees but amplified by symbolic and institutional power (Kuperman, 2015). Hate crimes illustrate the intersection of biology and social construction: evolutionary predispositions toward threat detection are channeled into racially or ethnically motivated killings, sustained by social narratives that dehumanize outgroups (Dunbar & Shultz, 2007).

Thus, while animals exhibit non-food killings to secure survival, status, or reproduction, humans expand these motives through layers of culture, religion, and politics. By examining these continuities, we can better understand how leadership, followership, and organizational systems can either restrain or inflame violent impulses (Wrangham, 2019). Recognizing that violence is both biological and socially constructed highlights the importance of designing structures that mitigate destructive tendencies while fostering cooperation and stability.

Comparing non-food related animal violence vs human violence

The Amplification of Primal Instincts

Humans often distinguish themselves from other species by claiming to be “civilized.” Yet, this self-awareness complicates the morality of killings not motivated by food. Unlike animals, whose acts of aggression typically stem from evolutionary imperatives such as territory, reproduction, or competition, humans possess the cognitive capacity to reflect on their actions, weigh moral consequences, and construct legal and ethical systems to govern behavior (Pinker, 2011; Wrangham, 2019).

Despite this, history is replete with examples of killings driven not by survival but by ideology, hatred, or spectacle. These acts are often justified through religion, politics, or cultural narratives rather than necessity (Juergensmeyer, 2017). The paradox is that while humans elevate themselves as “civilized,” the deliberate, premeditated, and often symbolic nature of such killings demonstrates an amplification, rather than a transcendence, of primal instincts. In this sense, consciousness does not eliminate violence but provides humans with the tools to rationalize, institutionalize, and even glorify it. This intentionality sets human non-food killings apart from animal behaviors.

Territory and Resource Protection

Among primates, chimpanzees engage in lethal intergroup raids, targeting rivals to expand territory and secure resources (Wilson et al., 2014). These attacks are highly coordinated, with males banding together to inflict fatal violence on neighboring groups. The evolutionary logic behind such aggression lies not in immediate sustenance but in long-term access to resources, reproductive opportunities, and enhanced group survival.

Human parallels are striking. Warfare, colonial expansion, and modern gang conflicts frequently arise from the same underlying motives of controlling land, ensuring dominance, and projecting power. In both species, the killing of rivals serves as a calculated strategy for reducing competition and securing advantages that extend beyond individual survival to collective prosperity (Wrangham, 2019).

Similarly, wolves have been observed killing coyotes or domestic dogs, not for food but to eliminate potential competitors within their ecological niche (Berger & Gese, 2007). This competitive suppression highlights a broader evolutionary principle: violence as a means of reducing or eliminating future threats to access resources. Humans replicate this behavior through ethnic cleansing, political assassinations, and organized crime turf wars. Here, the goal is not immediate consumption but the long-term consolidation of dominance and security (Pinker, 2011).

In both animals and humans, such acts reveal the evolutionary weight of survival through the domination of space and the exclusion of rivals. What distinguishes humans, however, is the cultural, ideological, and institutional framing of these killings, which amplifies their impact and moral complexity (Juergensmeyer, 2017).

Reproductive Advantage

Infanticide among lions and leopards illustrates a reproductive strategy in which males kill offspring sired by rivals. This brutal yet adaptive strategy accelerates access to mating opportunities (Packer & Pusey, 1983). By eliminating dependent cubs, new dominant males shorten the interval before females return to estrus, thus increasing their own reproductive success. This behavior highlights the evolutionary underpinnings of reproductive competition, where the drive to pass on one’s genes supersedes kinship bonds with unrelated offspring.

Similar behavior is found in other species, including primates, rodents, and even birds. These examples suggest that lethal violence tied to reproduction is not an anomaly but a recurring strategy shaped by natural selection to enhance individual fitness (Hrdy, 1979; van Schaik & Janson, 2000).

In humans, the direct killing of a rival’s offspring for reproductive advantage is exceedingly rare due to cultural, legal, and ethical prohibitions. Yet, the biological roots of reproductive competition remain evident in other forms of violence. Crimes of passion, intimate partner violence, and jealous homicides often stem from perceived threats to mating opportunities, fidelity, or lineage (Daly & Wilson, 1988).

For instance, stepchildren are statistically at higher risk of abuse and homicide compared to biological children. This disturbing pattern is sometimes explained as a byproduct of reproductive competition and reduced genetic investment (Daly & Wilson, 1985). Moreover, rivalries over romantic partners can escalate into assaults or murders, echoing the same competitive logic observed in lions and leopards, though filtered through human social structures (Wilson & Daly, 1993).

While human societies have developed complex moral and legal codes to suppress such impulses, these acts underscore the persistence of evolutionary motives beneath the veneer of civilization (Wrangham, 2019).

Dominance and Power

Cetaceans, such as bottlenose dolphins and orcas, have been documented killing porpoises and marine mammal calves without consuming them. Researchers suggest these killings may serve functions beyond immediate survival. They may be a form of practice for hunting, an outlet for social play, or demonstrations of dominance within their pods (Dunn, 2019; Patterson et al., 1998). Such acts reinforce social hierarchies and provide individuals with opportunities to display skill or aggression, elevating their standing among peers.

Humans exhibit parallel behaviors in which violence functions as a performance rather than a necessity. Examples include bullying, hazing rituals, gang initiations, and even gratuitous homicides committed for thrill-seeking or notoriety (Palagi et al., 2014; Pinker, 2011). In these cases, the act of violence signals dominance, reinforces group cohesion through shared aggression, or elevates the perpetrator’s social status.

For instance, violent initiation rites in fraternities, gangs, or extremist groups echo the dominance displays of dolphins and orcas. They transform aggression into a public performance of loyalty, toughness, or power (Volkan, 2014). Likewise, certain thrill killings or mass shootings are carried out with the intent of gaining recognition, instilling fear, or crafting an identity through violence (Leary et al., 2003). In both cetaceans and humans, killing becomes a grim performance that transcends survival, embedding aggression into social meaning, hierarchy, and identity.

Competition Reduction

Crows, ravens, and other corvids sometimes kill the young of other species. This behavior is thought to reduce future competition rather than provide nourishment (Kilham, 1989). Similarly, in meerkat societies, dominant females have been observed killing the pups of subordinate females. This ensures that limited resources are directed toward their own offspring (Young & Clutton-Brock, 2006). These acts demonstrate a proactive strategy of competitive exclusion. By eliminating potential rivals early, individuals or groups improve their chances of long-term survival and reproductive success.

While the violence may appear excessive when viewed outside its evolutionary context, such behaviors underscore the importance of competition as a driving force in natural selection. This shapes not only survival but also social hierarchies and access to scarce resources.

Humans mirror these strategies through symbolic and, at times, literal acts of competition reduction. In organizational settings, rivals may be discredited, excluded from opportunities, or sabotaged to prevent them from rising in influence or threatening one’s own position (Buss, 2016). In politics, character assassinations, smear campaigns, and systemic disenfranchisement serve the same function as corvid nest predation or meerkat infanticide. They weaken competitors before they can mature into formidable threats.

In more extreme cases, history reveals literal eliminations of rivals through purges, assassinations, or genocidal campaigns motivated by the desire to secure dominance and remove challengers (Volkan, 2014). Though human societies frame these actions in ideological, cultural, or organizational terms, the underlying motive—reducing competition to enhance one’s own survival or advancement—resonates strongly with patterns observed in animal behavior.

Animals and humans all evolved in the same biological world, although humans think they are better than animals. Yet we are more similar than different, especially when it comes to violent behavior. – Dr. Chris Fuzie, Ed.D.

Survival of the Fittest

Siblicide, as seen in birds such as eagles and herons, represents a striking form of non-food killing. In this behavior, stronger siblings eliminate weaker nestmates to secure scarce resources such as food, space, or parental care (Mock & Parker, 1997). This behavior reflects the harsh realities of survival in environments where parental provisioning cannot sustain all offspring. By ensuring that the strongest chick monopolizes resources, siblicide can maximize reproductive success for the parents, even at the cost of one or more offspring.

This lethal competition within kin groups highlights the evolutionary pressures that prioritize the survival of the fittest, even when genetic relatedness would suggest cooperation (Drummond, 2001). In this way, siblicide reveals the darker side of sibling dynamics in nature, where kinship does not guarantee solidarity when survival is at stake.

In humans, sibling rivalries rarely escalate to lethal outcomes. However, the underlying dynamics of competition for resources, recognition, and inheritance mirror the principles observed in avian siblicide. Psychological research has long noted that siblings compete for parental attention, social approval, and family resources. These rivalries sometimes persist into adulthood in disputes over inheritance or family authority (Sulloway, 1996).

In extreme historical cases, sibling competition has led to violent conflict, particularly in monarchies or dynastic systems where succession and power were at stake. Examples include the fratricides recorded in the Ottoman Empire (Peirce, 1993). Modern expressions are more symbolic, manifesting as legal battles over estates, career competition between siblings, or strained relationships rooted in perceived favoritism. These human parallels underscore that while cultural norms and legal frameworks generally suppress lethal outcomes, the evolutionary roots of sibling competition remain visible in both subtle and overt struggles for dominance, recognition, and resources within kin groups (Salmon & Hehman, 2014).

Conclusion

Non-food killings across species underscore the deep evolutionary roots of violence. In the animal kingdom, killings often arise from competition for territory, reproductive advantage, dominance, or the reduction of rivals. These motives enhance survival and fitness (Wrangham, 2019). While these primal motives are mirrored in human societies, they are magnified through cultural, technological, and social structures.

Human violence frequently emerges from religious conflicts, political alliances, and ideological extremism. Here, identity and belonging become rallying points for aggression (Juergensmeyer, 2017). Hate crimes, for example, demonstrate how evolutionary predispositions toward ingroup protection and outgroup hostility are amplified through social constructs of race, ethnicity, or religion (Dunbar & Shultz, 2007).

Unlike other species, humans institutionalize and ritualize violence, embedding it in systems of governance, nationalism, and cultural narratives (Pinker, 2011). Political assassinations, religiously motivated killings, and acts of terror highlight how evolutionary motives for dominance and competition intersect with uniquely human layers of ideology and belief (Kuperman, 2015). These expressions of violence are not merely biological impulses but are co-shaped by leadership, followership, and collective organization. Leaders may incite or restrain aggression, while followers can either amplify destructive behavior or redirect it toward cooperative action.

Recognizing these continuities across species highlights the dual role of human systems: they can either suppress or channel primal impulses. By understanding violence as both biological and social, societies gain greater capacity to design institutions, norms, and leadership structures that mitigate destructive behaviors while fostering cooperation and stability (Pinker, 2011). Ultimately, acknowledging the evolutionary roots of violence allows for more intentional development of cultural and organizational practices that favor peace, justice, and resilience.

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