The Goodness Paradox: How Humans Became Both Unusually Kind and Unusually Lethal

Wrangham does not quite say that humans are less violent than chimpanzees. He splits violence in two. Proactive aggression is planned: the attackers have already decided whom to strike, when to strike, and how to get away. Reactive aggression is impulsive and defensive, exploding within seconds of a threat. The striking fact about humans, compared with chimpanzees and bonobos, is a huge drop in that second kind.

He judges the gap with imperfect but vivid numbers. The human comparison is people living as hunter-gatherers in an Australian community with heavy alcohol abuse and a lot of domestic violence, about as bad, he says, as an ordinary society gets on this score. Researchers have solid counts of how often people actually hit one another. Set against several chimpanzee and bonobo sites, the apes still hit, chase, and charge between 500 and 1,000 times more often. The difference is two to three orders of magnitude.

Aristotle already noticed that humans behave in many ways like domesticated animals. People object by pointing to the world wars. Wrangham's answer is that those were proactive: gangs making deliberate decisions to attack when they hoped to kill and leave, which is how armies prefer to work. On death rates from coalitionary proactive violence, humans and chimpanzees look similar. We are not downregulated there. What is extraordinary is the quiet of everyday life inside the group.

Chimpanzees do practice a kind of tribal warfare. It was first observed in 1974, after Jane Goodall's Gombe study had been following chimps wherever they went for about five years. Until then, bananas at a feeding station had taught her a great deal, but not what happened at the edges of the range. Two forms of hostility then became obvious. One is ordinary: parties shouting at each other across a border. The other is not.

A party moves silently to the territorial edge and searches for members of a neighboring group. What they want is a lone individual. Wrangham has been with chimps who heard what they thought was a single call, touched one another, looked, and charged. Mid-charge the place erupted with a volley of calls; it had been one animal calling from a larger party. The attackers hit the brakes and fled home. If they do find someone alone and can sneak up, they hunt.

The damage is terrible and usually ends in an immediate kill, or in a victim crawling away to die hours or days later. Across about fifty observations from many sites, the average attack is eight males on one. Three to one happens, but it is getting risky. Eight means one male on each limb and four left to tear the thorax, rip off the testicles, and twist an arm until it breaks, with no weapons. If both sides discover several opponents, both retreat. "Nobody wants to get hurt," Wrangham says. "What they want to do is to hurt others."

The discovery wrecked Konrad Lorenz's 1960s claim, in *On Aggression*, that warfare is restricted to humans and that animals do not deliberately kill their own kind. Wolves, lions, hyenas, chimpanzees, and humans all do, and always when they feel safe: humans with weapons, animals with an overwhelming coalition. Lorenz, a wolf enthusiast, had watched captives roll over and offer the neck without a bite. In the wild, neighboring packs hunt each other, and as much as 50 percent of adult wolf mortality is other wolves.

Wrangham did his PhD at Gombe in the early 1970s, studying feeding while a handful of students watched the first intergroup kills. He describes Goodall as independent, courageous, and loyal to observation, unwilling to go beyond the data until it piled into a confident picture. She also paid tremendous attention to individuals. When she reported personality differences among the Kasakela chimps to Cambridge, her advisors said there was no research tradition for that and she should treat the animals as the same. Sixty years later, personality is a rich part of animal behavior. She stuck to her guns.

The method is stubbornly concrete because chimps are so like us that projection is easy. Define a hit, a bite, a gentle touch. Write every instance down. Tally how often A directs each act at B, C, D, and E. From those frequencies you extract relationships: relatively friendly, relatively competitive, even two standard deviations above the mean on friendliness. Friendship with a capital F becomes measurable, comparable across individuals, communities, and species. You never stop at "they seem rather aggressive."

The emotional trap is real. Goodall once offered ripe fruit to David Greybeard; he took it and squeezed her hand as if to say thank you, then, Wrangham thinks, gave it back. Infants were allowed to approach, tickle, and play. Some of those infants later used the knowledge that humans are physically weak. Frodo, as an adult, attacked people regularly and was dangerous enough to kill. He did kill: he took a human baby off a mother's hip on a path. In Uganda, Wrangham's team still drills students not to touch. One person did. It is a very bad idea, not because of that day's violence, but because chimps who learn our weakness can take advantage of it.

Wrangham's interest in violence crystallized at Gombe when the first intergroup infant kill and the hunting expeditions appeared. At the time, chimps, gorillas, and bonobos still looked like three similar forest apes, with humans off to the side. Even before genetics showed the special human-chimpanzee link, Goodall's chimps were already making tools, hunting and sharing meat, living under male political coalitions, and killing neighbors. Until then, Wrangham says, you could cheerfully treat humans as a species apart. After that, the psychology of war stopped looking like a recent cultural invention, or a matter of sin and the devil.

What chimps teach is that both species evolved a tendency to use violence when it pays. There is no free-floating instinct to kill. There is an instinct to use violence adaptively. Individuals do not benefit from a fight they might lose, so killing clusters in groups. Some communities are more violent than others depending on how often a large male party meets a lone victim, which is ecology. A judicious reading of history, Wrangham argues, fits the same pattern: war is commonplace because it is not an accident of civilization.

He will not pretend to know whether chimps grasp death as philosophy. Motivation, he says, is more like sex: males are not usually thinking about babies. They want to kill this individual, and taking the victim's perspective might only inhibit them. Selection, in that frame, has favored enthusiasm for killing enemies. Fridman cites the long human appetite for public executions. Wrangham's crucial word is tribe. People are not drawn to violence for its own sake so much as to harm those outside a social boundary. In some hunter-gatherer accounts, a stranger was shot on sight. What counted as human was the people who spoke your language.

Wrangham thinks violence is what created Homo sapiens, if sapiens means the gracile form: shorter face, smaller teeth, reduced brow ridge, thinner cranium. Bones from Morocco dated to about 315,000 years already show the start of that trend. He puts the beginning of the process at 300,000 to 400,000 years ago, with later skulls looking more and more modern. Those changes are the anatomical signature of reduced reactive violence. Among primates, humans are unique in having no alpha male who personally beats every other male.

Christopher Boehm's picture, which Wrangham elaborates, is that any man who tries to bully his way to the top is taken down by a coalition of beta males. That, Wrangham and Fridman agree, is a fair sketch of how human societies still work, and "I suppose that's what democracy is." Alpha males in other primates are specialists in reactive violence against status challenges. A famous Russian experiment that bred the tamest wild foxes produced, in a few generations, shorter faces, smaller teeth, feminized males, and smaller brains. The same suite appears in sapiens relative to earlier ancestors.

So sapiens is, in Wrangham's telling, the species in which selection against alpha males incidentally suppressed reactive aggression. Beta males discovered they could kill anyone who refused their values: females, young males, the next would-be tyrant. Two kinds of norms followed. Some are good for the group, such as thou shalt not murder. Some are good for males, such as males eating first when good food comes in. Conventional anthropology, he says, is oddly reluctant to credit warfare for sapiens replacing Neanderthals within about 3,000 years of entering Europe some 43,000 years ago. Larger groups, better weapons, and projectile technology are the obvious candidates. Interbreeding does not prove they only made love. "I think they made love and war," and the love need not have been gentle.

Wrangham splits sexual violence into between-group and within-group. The world has been slow to admit that sexual violence is routine in war. To him it is another case of power corrupting: frightened, elated, dehumanized soldiers meeting dehumanized women and getting carried away by opportunity. Gang rape followed by murder is hard to call adaptive in modern war, but it can sit on an older pattern that paid in less extreme conditions. Modern battle, in which a hierarchy sends men into a fight they may well not survive, is the opposite of a hunter-gatherer raid designed to get away with it. That, he says, is a novel evolutionary experience.

Inside groups, the statistically important form is intimidation and rape within ongoing relationships, not stranger assault. It can look odd that a man would coerce someone he already lives with. The point is not only sex. Relative power in the relationship has continuing significance for domestic life and for whether the man gets his way. Sexual aggression becomes a tool to regain and enlarge that power. Parallel patterns show up in other primates: even in groups where females mate with many males, a male may target one female, and the more aggressive he is, the more she conforms when he wants to mate.

Males have long gotten away with more than females in these conflicts. Punishment for a husband killing a wife has historically been lighter than the reverse; adultery rules tilt the same way. Wrangham traces that double standard to the beta-male takeover 300,000 to 400,000 years ago, when breeding males began imposing their norms. When Jordan Peterson says we are not a patriarchal society, Wrangham hears a legalistic claim. Formal law is more even-handed than a century ago, and women vote. De facto, he says, society still supports men better than women in these conflicts. A woman with many sexual partners is treated more rudely than a man with many. Human nature, including the male pressure women find unpleasant, does not vanish when the statute book changes.

Is Genghis Khan a deep sample of human nature or a rare exception? Wrangham finds it easy to imagine that most men could have become Genghis Khan. A streak of psychopathy is possible, but the decisive ingredient is position. Once you are immensely powerful, willingness to do terrible things for yourself and your group rises sharply. Stalin and Mao, in his reading, do not show obvious psychopathy in their early histories. As big leaders they become psychopathic in the moral sense: they stop considering the harm done to victims. Lord Acton's line is not only that power corrupts. The next sentence, often forgotten, is that great men are almost always bad men.

Fridman pushes a different emphasis: the most destructive men convince themselves. The idea is what is psychopathic. Stalin believed communism was good for the world, so killing some people for a global victory looked like a bargain. Wrangham is not fully convinced. Stalin murdered communists, including Kirov and Trotsky, rivals on his own side. What he feared was challenge. Wrangham also notes the export of Ukrainian wheat and the mass starvation that followed, done to sell grain and build Soviet power. They agree, though, that the dance is not only personal. "We are fiercely tribal," Wrangham says, "and the tribalism resides particularly in male psychology." Assemble males who share a tribal identity, and they can exert force with little concern for the damage.

Almost all cognitively complex animals live inside tribal boundaries. Baboons do not kill across groups because thirty versus fifty is too risky, yet they still know whose side they are on, and winners get more land, more safety, and better reproduction. Fridman asks whether tribalism is a feature or a bug. From natural selection's point of view it is a feature: it evolved because it benefited those who practiced it. If a bug means something the species would be better without, Wrangham says yes, and then adds that by that standard males themselves are a bug. Fridman, who trains in martial arts, objects that controlled conflict can be productive. Wrangham will grant that ideas can clash on a log without a bomb. He thinks it is ridiculous to call violence a good thing, and he cites Steven Pinker's evidence that death rates from violence have declined, even counting the world wars of the twentieth century.

Wrangham is a member of groups that would like to see weapons go, but he sees no reasonable future clearly in view. Orwell's stalemate of two or three immortal superpowers does not look evolutionarily stable. The world has 170 or 190 nations, dominated by a few, arms pointed at one another, and the hope that talks can prevent a conflagration forever seems wildly optimistic. A single world government terrifies him for its abuse potential, and he cannot see how to get there without a war. Fridman offers cryptocurrency as a technical way to pry monetary power out of any one government and let ad hoc societies fork. Wrangham finds that interesting. The future, he says, may well emerge from some surprising direction like that.

He is surprised, mainly, that nuclear accident has not already happened. Accounts of misread intentions and apparent launches are close enough. A nastier regularity is that the longer powerful states go without war, the worse the next war tends to be. After 1945, formal dominance was reset; in the peace, de facto rank drifts as economies and militaries rise and fall. China left the war low-status and is now high-status. In chimpanzees, that mismatch predicts conflict. Mutually assured destruction, though, fits a psychology that is crystal clear in other animals: do not fight if you will get hurt. That is likely why the United States and Russia have not used nuclear weapons since 1945. If accidental launch can be solved, MAD might nest in human psychology. The challenge has not really been faced, he says, with Taiwan and the Pacific as the obvious flashpoint.

Asked for a hopeful case, Wrangham will not write a full optimistic script. Surprises come from odd directions; perhaps robotics, or chips in brains that share information instantly, will undermine the motive for conflict. Fridman wants to keep the magic of life, not sedate the species. Wrangham's thought experiment is to stop producing males, because lust for power is concentrated there. He has nothing against men as individuals and credits male art and music, but he doubts that is uniquely male, and evolutionary theory says males benefit more from winning conflicts. Reproductive technology may soon let women breed without men. The fatal problem is tribalism: some country would refuse, and then, because they kept males, they would take over. Empathy cannot simply be taught against evolutionary psychology. The famously peaceful society he mentions in Thailand required teaching, including punishment. "It requires work."

*The Goodness Paradox* names the fact that humans sit at extremes of both violence and nonviolence. We are one of the few animals that use coalitionary proactive violence to kill our own species in large numbers. We are also extraordinarily repressed in reactive violence. Chimpanzees are high on both. Bonobos are lower than chimpanzees on both, yet still hundreds of times more reactively aggressive than humans. We kept proactive killing high and drove reactive aggression down, which is why we can be so calm with strangers and still be one of the worst killing-machine species that has ever existed.

Political philosophy spent centuries in a fight between Hobbes and Rousseau, or rather their followers. Hobbesians say we are naturally horrid and need a Leviathan. Rousseau is read as saying we are naturally good until culture ruins us. In the last few decades, anthropologists such as Christopher Boehm and Bruce Knauft have said the obvious: we are both. Wrangham thinks we can now say why. We come from ancestors elevated on proactive aggression, hunters and killers of animals and of each other. Then we downregulated reactive aggression. Once alpha males are gone, a group can stop living on a hair trigger and share tools, food, ideas, and care for the sick.

That cooperation, whatever the military details, is his candidate for why sapiens groups of scores replaced Neanderthal bands of perhaps fifteen or twenty, isolated enough to inbreed, even fathers with daughters. Married men in recent hunter-gatherer ethnographies still police unmarried men with camp rules: stay in the firelight, or go live in the bush for months, because the men with wives do not want horny bachelors sneaking around. The origin is not pretty. The product is a species that can sit together without exploding, and then, when it feels safe, kill on a scale no chimpanzee ever managed.

*Catching Fire* is about the genus Homo, specifically Homo erectus, not sapiens. Around two million years ago, a line of australopithecines, chimpanzees standing upright with chimp-sized brains, big jaws, and raw diets, produced erectus. Mouth, jaw, teeth, and, to judge from ribs and pelvis, gut all shrank. Climbing adaptations disappeared, which means erectus slept on the ground. Wrangham has slept in the African bush; he would not lie out on a moonless Serengeti night among predators without fire. Modern human guts are about two-thirds the size expected for a raw-food ape. Between two million years ago and now he sees no later anatomical jump that matches the invention of cooking. The erectus package is exactly what you would expect: softer food, smaller guts, and a commitment to the ground.

The leap from fire to cooking is not a stroke of genius. Every animal tested, including naive great apes, prefers cooked food to raw. Animals are always hunting for easier digestion: more sugar, free amino acids, softer texture, fewer toxins. If food rolls into a fire, five minutes later it tastes better. The real leverage is time and energy. The human brain is about 2.5 percent of body weight and burns about 25 percent of calories. Gorillas may chew seven or eight hours in some seasons and then wait for a full stomach to empty; they are already near a rate limit, and their brains are smaller relative to body size than a chimpanzee's. Cooking raises net energy and cuts chewing from something like half the day in our ancestors to about an hour now. The surplus is hours, not a few calories.

Wrangham's guess is that males spent those hours hunting. Chimpanzees hunt two or three times a month for about twenty minutes. Humans may hunt twenty times a month for about six hours: high risk, high gain. Raw meat is loved and slow. After a monkey kill, the strongest chimpanzee retreats up a tree while others beg; blood drops onto leaves that low-ranking females and young race to lick. Sometimes the owner drops the meat and goes back to fruit because fruit becomes energy faster. Cooking removes that bottleneck. Then, late in the story, sapiens brains start shrinking, at least by 30,000 years ago. Domesticated animals lose about 15 percent of brain size without a clear loss of cognitive ability. Wrangham reads it as a younger, more pedomorphic brain. Children lack wisdom, not raw learning. We also have smaller brains than Neanderthals. Fridman jokes that size is not everything.

Fridman boils the story down to two moments: fire with erectus, then beta males killing the alpha so cooperation and language could exist. Wrangham's amendment is that chimpanzees already kill males inside the group, but not as a systematic coup against the alpha, because without language you cannot know who will show up. Against outsiders, everyone already hates those guys. The alpha has allies. Language good enough for conspiracy starts a feedback loop of tolerance and richer speech. Under a dictator, Fridman notes, millions are terrified as individuals because nobody knows whom they can talk to. The beauty of the human mind, Wrangham says, is not a separate selection for poetry at sunset. It grows on platforms: more energy for larger brains, cooperation amid leftover conflict, and sexual selection as people show off to be chosen.

A rainforest belt along the equator, spanning some twenty-two countries, still holds Africa's three apes. Gorillas split first, about ten million years ago, perhaps as recently as eight, and likely remain close to that ancestor: the largest apes, more dependent on herbs and stems than fruit, living in stable groups with one alpha male. Before Dian Fossey was murdered, Wrangham spent a week or two at her camp. A young female, Simba, stared at his two companions, then touched his forehead with her knuckles. Digit, a young male interested in her, later charged down the path, sidestepped the two women, and knocked Wrangham about five yards into the bushes. He loves the deliberateness of it, and the way gorillas hold your eye as if trying to read your mind. Chimps and bonobos never do.

Six or seven million years ago the human line left the forest and became australopithecines; the chimpanzee-bonobo ancestor stayed. One branch crossed the Congo a million or two years ago and became bonobos. Chimpanzee communities of twenty to two hundred share a territory that males defend while females wander and raise young independently. Females mate with every male, repeatedly, as if to leave a memory: I mated you, so do not be mean to this baby. Wrangham's favorite chimp scene is quiet. Hugh and Charlie, perhaps brothers, exhausted after an eleven-kilometer day, spent the next day in one tree. Charlie finished his seed branch, groomed Hugh, got bored, and moved Hugh's branch behind his own back. Hugh finished his mouthful, groomed Charlie until he could reach the branch, and took it back. A polite request, and it worked.

Bonobos look like self-domesticated chimpanzees: reduced male-female difference, shorter faces, smaller teeth, smaller bodies, smaller brains. They are far more peaceful; the data now show a statistical difference in aggressive killing. They are famously erotic. Females have especially large swellings and excitedly rub clitorises together, apparently to orgasm, often around social tension, before or after, as a way to confirm friendship and cut the chance of a fight. Conflict resolution through sex. "Make love, not war" is the usual slogan, and for once Wrangham lets it stand.

Wrangham loves nature and is pessimistic about saving it. Whenever habitat protection collides with a little extra food for someone's children, humans tend to win. The trend in habitats and numbers runs the wrong way, with occasional local rescues. He puts the moral limit bluntly: we are essentially a single tribe, and no one will die twenty people to save an elephant. The practical path is to make the best remaining places, often existing national parks, valuable enough that keeping them serves human survival. In Uganda his colleagues fight for Kibale National Park, the country's largest chimpanzee population, plus elephants, birds, butterflies, plants, and visitors. That may mean much higher ecotourism fees, done right, plus climate and rainfall arguments, plus, sometimes, aesthetics. Rich countries, he says, must invest far more, at home and in the tropics.

African population trends, including the possibility that Nigeria becomes the world's most populous country within a century, point toward massive conversion to farmland. Wrangham once heard E.O. Wilson on the prospect of Earth as a single human feedlot. Wilson's call to devote half the planet to nature is wildly ambitious and optimistic, but without a goal of that scale, Wrangham doubts much will be saved. Fridman offers Central Park: green space on some of the world's most expensive land, proof that preservation can happen even for beauty and respect for origins. We are lucky, Wrangham adds, still to have chimpanzees, bonobos, and gorillas. We could spend billions looking for bacteria on Mars. We should spend billions keeping substantial populations of the relatives who still teach us what we are. From space, he recalls Hermann Müller's image: the whole of life would look like a kind of rust on the planet.

The meaning of that rust, for Wrangham, is that there is no meaning. The real mystery is why there is a universe at all. That "why" propagates through galaxies, star systems, planets, proteins, cells, complex bodies, and a clever fish crawling onto land. Then fire: some clever man or woman lit it, and now we are here. He finds that story more interesting than the religious ones. Fridman tries a virus analogy: maybe civilizations, like pathogens, fail if they are too peaceful or too violent. Wrangham does not take the bait. He sees no evidence that being too peaceful is a problem. There are many ways to die without violence, and violent death is premature death. He does not mind people dying. He minds people dying young. He is not afraid of his own death, only frustrated. He enjoys life. He does not want to leave the party.