Serendip is an independent site partnering with faculty at multiple colleges and universities around the world. Happy exploring!

Oh cruel world: the evolution of cruelty in human beings

Molly Tamulevich's picture

This semester, I designed and participated in a praxis class entitled Abuse and Relocation in Shelter Environments. My field work takes place at PACCA, the Philadelphia Animal Care and Control Association. After working with dogs in a poorly funded shelter in Mérida, Mexico last year, I thought that I would be mentally prepared to launch myself into work in the U.S. However, what I discovered in Philadelphia is that cruelty towards animals in this country parallels the cruelty I found in Mexico. Every week, I see new evidence of abuse and neglect: starvation, scars, open wounds and overwhelming fear. I have learned about mange, pit-bull fighting, animal branding and pressure sores, which are abscesses that appear when a bone begins to protrude from the skin of an emaciated animal. As I conduct research about animal abuse and the people who commit it, I wonder where cruelty originates. Is there a template for cruelty laid down in the human brain? Is it something that is unique to our species? Why do human beings find pleasure in deliberately inflicting pain on other living things?

. According to Victor Nell's article, Cruelty’s rewards: The gratification of perpetrators and spectators, cruelty is a, “behavioral by-product of predation.”(1). Nell sees cruelty as a socially supported, natural tendency which produces endorphins at the smell of blood and screams of suffering. Although predatory mammals are physically drained by the combination of pursuing, killing and protecting the carcass of their prey, meat eating is worth the effort because of increased dopamine levels in the predator's brain. Like a runner’s high, predator’s dopamine receptors are extremely energized when confronted with the challenging process of hunting and floods of energizing chemicals reward the predator's physical exhaustion. Predators connect this high with obtaining meat, a preferred food source and symbol of strength and virility. Predators in the wild hunt because, although it is dangerous and exhausting, it is ultimately a rewarding experience.

Nell argues that cruelty requires a theory of mind. Most animals cannot imagine themselves in the place of another animal and cannot understand that their actions cause that animal pain; in other words, they lack empathy. Humans, however, have a well developed sense of empathy, and with that in mind, they are fully conscious of the pain they inflict on others, be it physical, mental or emotional. With this awareness, many hunting and gathering societies perform rituals to thank the spirits of the animals they kill. Just because humans can empathize, doesn't mean that they lack endorphin rush that is present for every other predator. It makes sense that hunters enjoy the thrill of the hunt because their bodies respond to pleasurable chemical signals. Hunting lives in a grey area of cruelty. If human beings are conscious of the pain taking a life causes, are we under a moral obligation to give up eating meat? At one point, fur and skins kept human beings warm. Because cruelty free alternatives now exist, the use of fur as cruel is controversial, and seen by some as inhumane and barbaric.(2)

One cannot overemphasize the power and dominance gained from acts of hunting. The individual who controls the meat controls the power and this power gives the successful hunter access to status, power, and sex. . In chimpanzees, a dominant male will beg from a non-dominant male who has captured a monkey. Because meat is such a highly prized commodity, it will temporarily alter the heirichal pattern of power within the troop. Similarly, when sharing meat, males who participate in the hunt are more likely to receive a larger share of the meat than those who did not. (3) Chimpanzees will bargain for food with sexual opportunities, and therefore possession of meat benefits a male’s reproductive success. Similarly, by bargaining any resource, human beings elicite power. Money, sex, food and drink are all tools that separate the haves from the have nots.

At the junction between pain and power lies cruelty. The sight and smell of blood and the sound of screaming activates the release of endorphins in high concentrations. Participation in a blood sport, beating a child or a planned killing triggers endorphine release. Because of this, a crowd, at any type of fight, gets riled up very easily. The combatants give off signals which trigger ancient predatory instincts, signaling an imminent reward. A person who abuses an animal asserts their dominance over it. It is not a matter of hating the animal that triggers the abuser's cruel treatment. It is the high the abuser feels after physically exerting themselves over a weaker being.Because cruelty towards others inspires fear, the abuser may gain a certain status or power because others are afraid to challenge his or her dominance.

Is it possible that humans are the only animals capable of committing cruelty? According to De Waal, we are not. In Our Inner Ape, De Waal provides example after example of empathy and cruelty among chimps and bonobos. Empathy, the ability to understand and perceive the emotions of others is another trait that assumes theory of mind, and he argues that a wide range of animals from dogs and cats to chimpanzees and bonobos possess this trait. Waal describes a female bonobo's empathetic attempts to assist a stunned bird to fly again. She spread its wings with her fingers and tossed the bird into the air. When the bird fell to the ground, she sat with it until it recovered and could fly on its own. This compassion for a different species is not as remarkable as the fact that the bonobo tailored her efforts to fit what she had observed of birds, that they fly and that they spread their wings to do so. The bonobo demonstrates a high level of intelligence in realizing the plight of the "other," especially because it is unlike her.

Because bonobos possess empathy; they are aware of an animal's pain, which establishes that they are also aware of cruelty. Chimps posses this theory of mind as well. De Waal describes a game that a group of captive chimpanzees played in which they lured chickens to them with bread and then poked them with sharp wire for fun. The chimpanzees utilized thier physical and intellectual power over the weaker, less intelligent chickens to inflict pain upon them. The chicken's pain amused the chimps, illustrating the chimps' capacity for cruelty. Chimps also attack others in pairs, one holding the victim down and the other beating the helpless captive. In making their victim immobile in order to inflict more pain upon them, chimps exhibit a premeditated agenda to do harm. The infliction of pain releases endorphins in the chimps, rewarding them for their cruelty. In these ways, both chimps and bonobos exhibit traits that suggest a theory of mind, and because chimps, bonobos and humans are closely linked, this implies that human beings are born with the potential to enjoy the suffering of others.

Chimpanzees, who are active hunters, are more likely to use violence to resolve disputes. Bonobos, on the other hand, will eat meat opportunistically and are known for their use of sex to pacify members of the community.(4) Although it is controversial to ascribe such traditionally human traits to animals, it makes sense to observe chimp and bonobo society, as they are our closest living relatives . Assuming theory of mind, the correlation between hunting and cruelty in animals is only one theory to explain the origins of cruelty. However, considering that human being who adopt a vegan or vegetarian lifestyle often do so as an opposition to cruelty, what does that say about the morality of eating meat? When we know the pain meat eating, fur-wearing and animal fighting cause, is it cruel to continue to participate in these activities? By normalizing meat-eating, American culture assumes that humans will participate in this passive cruelty towards animals unless they take a stand against societal norms. Cruelty is a trait that evolved as a by-product of predation, but we can choose to indulge in it as much as we see fit. Unless there is a decreased empathy response in any given person, participation in cruelty is the choice of the individual.


(1) Nell, Victor. Cruelty's Rewards: The gratifications of perpetrators and spectators. BEHAVIORAL AND BRAIN SCIENCES (2006) 29, 211–257.


(3) De Waal, Frans. Our Inner Ape. 2005. Penguin Group. New York, New York.

(4)Stanford, Craig B. American Scientist Online. Volume: 88 Number: 2 Page: 110