The Goodness Paradox: The Strange Relationship Between Virtue and Violence in Human Evolution


Already in the preface, Richard Wrangham’s The Goodness Paradox put a smile on my face. Wrangham there advocates the position that humans are naturally capable of both good and bad. In my own philosophical-naturalist musings, I’ve always operated from that principle, so evident in history it’s distressing that so many evolutionary biologists, not to mention humanists, have taken the position that humans are inherently one or the other.

Wrangham sets out his strongest case on this divisive issue at a scientific level. His extensive parsing of the latest research is crucial. He, too, starts out by citing notorious examples of human goodness and badness, including in the same person, concluding emphatically, “The potential for good and evil occurs in every individual.”

Humanists will appreciate that  Wrangham carefully considers methodological issues before diving into the evidence. The value of research on primate behavior to assessing human evolution is highly debated. Even human variation raises the question of whether there is a “human nature” at all. Throughout, he questions research results to distinguish what is solely characteristic of other species and what can be analogized to humans.

Central to his substantive argument is the distinction between two types of aggression or tendency toward violence. One type is reactive, the other is proactive. Studies show that different species of hominines and certain other animals display different ranges of aggressiveness of each type.

Reactive aggression is the spontaneous response to threat or provocation. Humans have relatively less reactive aggression than primates. Proactive aggression is planned and deliberate, typically, but not always manifesting in tribal, civil, and international war. Humans are particularly aggressive in this proactive sense, exhibiting a far more butcherous aggression in war than primates. Of course, that proactive aggression is directed at “other” groups of humans. That said, some individual and groups of humans are naturally more proactively aggressive than others.

Wrangham cites a great example to illustrate the difference between reactive and proactive aggression:

The anthropologist [Sarah] Hrdy noted that to pack hundreds of chimpanzees into close quarters on an airplane would be to invite violent chaos, whereas most human passengers behave sedately even when they are crowded. As Dale Peterson observed, however, intense screening is needed to ensure that a secret enemy will not carry a bomb on board. The contrast illustrates the difference between our low propensity for reactive aggression and our high propensity for proactive aggression.

Critically, the early evidence suggests there is indeed no genetic connection between propensity for reactive and proactive types of aggressiveness. Human domestication of other animals shows that reactive aggressiveness in a species can be reduced without affecting the proactive aggressiveness of the species. Housecats, for example, are comfortable with humans but retain their instincts for killing for food and fighting for territory.

Wrangham argues that because humans have low propensity for reactive violence, they were domesticated. Implicitly, he equates low propensity for reactive violence with domestication, although one can quibble with the label. He covers the history of the idea of humans as having been domesticated, including how the concept was twisted into eugenics and Nazi views of Aryan superiority.

But the big question is, who domesticated humans? Wrangham disregards supernatural explanations in favor of the assertion that humans self-domesticated. Like a good naturalist, he examines the evidence. Evidence concerning domestication of other animals by humans shows that certain anatomical changes come with domestication. Compared with their wild cousins, they become smaller in stature, have smaller teeth, show less size difference between male and female, and have smaller brains. These changes are called the “domestication syndrome.” He then identifies similar changes in Homo sapiens between about 30,000 and 12,000 years ago. Wrangham argues this time period is when humans self-domesticated.

That framework calls for an explanation of how humans self-domesticated. He begins exploring that question by acknowledging that “domestication” is an inapt term, because it implies that a domesticator is necessary. He covers the evidence that a number of non-human animal species that could not have come from a domesticator in fact exhibit a low reactive propensity for violence. The best example is bonobos, who have a common ancestor with chimpanzees. Their genetic lines diverged between nine hundred thousand and 2.1 million years ago. Now, bonobos in the wild engage in little reactive violence, while wild chimpanzees exhibit a lot of behavior in that category. Bonobos and Homo sapiens have characteristics associated with the domestication syndrome; chimpanzees do not.

The idea that humans have self-domesticated is, in turn, central to Wrangham’s thesis about the evolution of goodness. He cites reams of scientific studies showing that humans in hunter-gatherer societies tend to have moral standards that, as I read it, require either family or group elders of socially disruptive individuals to impose what he calls “capital punishment.” Capital punishment is central to Wrangham’s construct of how humans self-domesticated: small groups of humans devised social norms and mechanisms to kill individuals who engaged in excessive reactive violence against members of their own tribe. In the process, they cut violent humans out of the breeding pool over thousands of years.

Reading this, I realized for the first time that imprisonment and judicially ordered capital punishment (now mostly discredited) in contemporary society inherently restricts the reproduction of offenders deemed violent and anti-social. It puts the systemic racist bias of the US criminal justice system against racial minorities, especially Black men, in a new, even more pernicious light.

Wrangham argues that the reduced tendency for reactive violence, however it came about, was accompanied by increased in-group tolerance. Indeed, human infants generally recognize fairness and approve punishing those who are unfair. That corresponded to the development of codes of conduct for behavior toward group members.

Specifically, Wrangham points to evidence that mostly only males benefited from self-domestication. The reduction in reactive violence enabled men to cooperate against the alpha male. Collaborative men in the group replaced the dominance of the reactively violent alpha male with a democratic sharing of power among themselves. In my research, this is borne out by evidence of possibly the earliest account of democracy occurring among warriors in ancient Babylon deciding collectively nearly 5,000 years ago whether to wage war against a neighboring tribe. However, women and children, not to mention men who violated the norms established by the male control group, were subservient.

As with my example from Babylon, Wrangham sets a larger context of existing hunter-gathering humans in which human males and, at times, females apply a moral code that can include killing of socially unacceptable individuals. He asserts an ambitious agenda of showing that killing specifically resulted in the domestication of humans. In the end, the course of his argument relies on a broader level of social enforcement of moral codes through various means that include execution. I will leave to the individual reader to conclude whether the evidence Wrangham cites is sufficient to that cause.

The clear control by cooperative males of the rest of human society enabled greater group power and cohesion. Language was a hugely valuable new trait that enhanced the establishment of group norms and their enforcement. Enforced conformity allied with more lethal killing ability that came with new weapons and the tactical advantage of language empowered humans to exterminate hominine competitors. Naturally, the troubling legacy of that power is the savagery of internecine warfare in the common era.

Indeed, Wrangham argues that occasionally human societies have failed to control their most aggressive members. When they have gained control of the structures of modern societies, they have instigated conflict with cataclysmic consequences. In the era of President Donald Trump’s reactive and proactive aggressiveness, the book has its most profound implications. As much as the republican form of government in the US has led to consolidation of power to the benefit of the rich, it has generally precluded highly aggressive individuals from becoming president. However, the pluralistic reorganization of the two-party system has allowed someone like Trump to be nominated and, against a candidate unprepared to deal with his aggressiveness, win the most powerful position in the world.

Wrangham’s words of wisdom bear witness to our present circumstances: “To avert episodes of violence we should constantly remind ourselves of how easily a complex social organization can decay, and how hard it is to construct.” Just as Thomas Jefferson advocated a revolution every twenty years, all peace-loving, egalitarian people must collaborate to challenge highly aggressive individuals who would undermine cohesion and tolerance to the detriment of the greater good.