The Yanomamö Said the Only Sensible Reason for War Was Women

Lex Fridman opens with a blunt question for David Buss, the University of Texas at Austin evolutionary psychologist often counted among the founders of the field: in the history of human civilization, what has mattered more, sex or violence? Mating strategies or military ones? Buss refuses the fork. Both matter. Humans are a sexually reproducing species, so everything has to go through sex. For anyone alive now to exist, every ancestor in an unbroken chain had to select a fertile mate, attract that person, be mutually chosen, stay together long enough, do the sexual work of reproduction, and keep the children alive.

Drop any link and the lineage ends. That is why, Buss argues, human mating psychology is so rich and so complicated. Survival, on this view, is only a means. Reproduction is the end that designed the machinery. The conversation that follows—three and a half hours on dating, jealousy, infidelity, pornography, and love—is an attempt to describe that machinery without flinching at the parts people would rather leave unnamed.

Violence still will not shrink. Buss says humans evolved in small groups with a fair amount of intertribal warfare. The harsh realization, from a purely reproductive standpoint, is that it has historically paid to conquer a neighboring group, kill the men, and take their resources—territory, tools, weapons, and women. The asymmetry is stark. Women have fought in wars, but Buss says there is not a single case in recorded history of women forming a war tribe, attacking another group of women, killing them, and capturing the men as husbands. In the ethnographic record, the male version of that pattern is common.

Napoleon Chagnon, who spent years with the Yanomamö, asked them why they went to war. They said to capture women, of course—the only sensible reason. When he explained that his own culture fought to spread democracy and ideas, they fell off their logs laughing. Why risk your life for anything else? Reputation complicates the joke. If a group is attacked and three women are stolen and there is no retaliation, the group looks exploitable, and other neighbors pile on. Attacks, counter-attacks, and retribution cycle like the Hatfields and McCoys. Reputation management, Buss says, is part of tribal war.

Inside groups, conflict is often ritualized. Yanomamö chest-pounding duels start twenty paces apart: one man runs in and punches the other in the chest; the recipient has to stand there, then returns the blow; last man standing wins. Get good at it and you break ribs. The rules about where the chest ends are conveniently loose. The Yanomamö also split men into unokai, those who have killed, and non-unokai, those who have not. Historically the unokai had higher status and more wives in a polygynous society. Buss notes that something like 83 to 85 percent of what anthropologists now call small-scale societies were polygynous. An anthropologist had just corrected his vocabulary: do not say traditional societies. Words, he adds, can hurt people and inspire them. They are funny, powerful things.

Fridman asks for the magic ingredient that gave rise to *Homo sapiens*: fire, cooking, collaboration, shared ideas, the contemplation of death? Buss will not isolate one factor. He knows Richard Wrangham, a former Michigan colleague, and thinks Wrangham's case for fire and cooking is serious. His own candidate is at least partly the uniqueness of the human mating system. Chimpanzees, our closest primate relatives and Wrangham's specialty, have essentially no long-term pair-bonded mating. A female comes into estrus, most of the sex happens in that window, and then it is over.

Humans evolved long-term pair bonding. It is only one strategy, Buss says, but a central one, and it arrives with male parental care. Chimpanzee males inseminate and then do little. Human males invest, in the modern environment sometimes for decades—Buss cannot resist a line about boomerang kids. Compared with the vast majority of mammals, we are a heavy male-parental-investment species. That combination, pair bonds plus fathers who provision, is a large part of what makes us strange.

Asked to define mating, Buss reaches for a category much wider than intercourse. It includes mate selection, preferences, attraction, retention, poaching, and expulsion. It includes the decision to stick it out and raise several children. It absolutely includes the emotion of love. As an undergraduate he was taught that love was an invention of a few Caucasian European poets a couple of hundred years ago. Cross-cultural evidence killed that story. Not every person in every culture falls in love, but some people in all cultures experience the emotion we call love.

Romantic love has phases. There is infatuation: obsessional thoughts, work that will not hold still, what Buss calls ideational intrusion. That state cannot last. Then comes what he apologizes for calling the phase of intense, almost frantic sexuality. People have other adaptive problems to solve, so that heat subsides. In many couples it becomes a warm attachment, still romantic, not brotherly—long-term cuddling, not a roommate arrangement.

Fridman wants a broader word. Looking at a landscape can feel like love: joy, beauty, a gratitude at being alive that echoes the chemicals of romance. Buss had not thought of it that way. He would reach for *awe*, the feeling in front of a sunset. He grants that a sense of beauty and a sense of sexual appeal intersect in fascinating ways. For the rest of the conversation, though, he is tracking the mating kind.

Mating is inherently competitive because desirable partners are in short supply relative to the number of people who want them. Even after mutual choice, the game is not over. That is why mate poaching exists, a strategy Buss has studied in the lab with David Schmitt. The uniquely human move is that we compete with words. People spend enormous effort building reputations, maintaining them, and trying to recover them after a fall. Language is a courtship signal—verbal fluency, later poetry—and it is a weapon.

One of Buss's early papers catalogued derogation of competitors: the ways people impugn a rival's status, character, and reputation to make them less desirable. Women and men both do it. Animal biologists study contest competition, the physical battle, and early mate-competition work followed those ostentatious fights. Buss says the overlooked domain is women competing through language, and how observant they are about subtle imperfections in rivals.

He tells a story from his youth. He spent a party talking to a very attractive woman. Leaving, his girlfriend said, casually, had he noticed her thighs were heavy? He had not. The next time he saw the woman, his attention went to her thighs. Why would verbal input change what a man can see with his own eyes? Two answers. Attention: a small deviation from symmetry, once named, gets magnified in the attentional field. Status: who you are with is a reflection of your own rank. In the 2016 Republican primary, Donald Trump told voters to look at his wife and then at Ted Cruz's, attacking Cruz's wife's appearance. With a large enough platform, a few sentences can move a status hierarchy.

Fridman pushes back: the pool of desirable mates stays small because *desirable* is socially defined, almost on purpose. Buss grants part of the point. Humans have adaptations for detecting differences. A Martian might think we all look alike, the way we think zebras do. In mating, friendship, and coalition choice, the differences are what matter. He once watched a Miss America pageant with a group who said, of Miss North Carolina, what a dog—among fifty women already picked as the most attractive in their states.

He still resists *socially constructed* when the phrase is taken to mean *arbitrary*. Social science used to say you cannot judge a book by its cover, that beauty is only skin deep. Physical appearance, Buss argues, carries a wealth of information: health, male formidability, female fertility. Cues to youth and health in women include clear skin, full lips, clear eyes, lustrous hair, a low waist-to-hip ratio, and symmetrical features. We are a bilaterally symmetrical species, and everyone deviates from perfect symmetry because of mutation load, environmental insults, and disease in development. Some tastes are culturally arbitrary—Māori lip tattoos, for example. The fertility and health cues are not.

A third human peculiarity belongs here. Chimpanzee males have no trouble knowing when a female is fertile: bright red genital swelling, olfactory cues, estrus. Humans have relatively concealed ovulation. There is a little evidence of subtle changes in women not on hormonal contraceptives, but ovulation is mostly hidden, which is remarkable given how close we are to chimps. Fridman asks if it is a bug. Buss thinks it is an adaptation in women, a feature. If a man cannot know when a woman is fertile, he has to stick around. Long-term pair bonding, on this view, co-evolved with concealed ovulation, and with a sexuality that runs through the whole cycle rather than a brief heat. Mating becomes a year-round part of human interaction in a way it is not for chimps.

What men and women want depends on whether the search is long-term or short-term. Long-term mating, Buss says, is a very complicated optimization problem, more so for women. In his human-sexuality course at UT Austin, back when there were chalkboards, he would ask a class of one to two hundred: what do women want in a long-term mate? Kind, understanding, intelligent, healthy, a good sense of humor, shared values. He would fill five blackboards and run out of space.

Magnitude matters as much as the trait list. Students wanted a partner generous with resources—until Buss asked about a man who hands his paycheck to the local wino. Not that generous: generous toward *me*, not indiscriminately. Ambitious and hardworking, but not a workaholic. Then the traits interact. Turn to the men and the chalk dies after a blackboard and a half. They cannot think of much else.

The overlap is real: intelligence, health, humor, an agreeable personality, someone not too neurotic or moody. The key differences sit in a few domains. For men, physical appearance and youth are the two big ones, prioritized more than women prioritize them. That is why love at first sight is mostly a male story. A man walks into a party, sees a woman across the room, and says he is going to marry her. Women rarely do that; most men do not either, but men are much more inclined. From a purely reproductive view, job one is selecting a fertile mate. Ancestors who chose postmenopausal partners did not become our ancestors. Fertility cannot be observed directly, so the mind computes from probabilistic cues. In short-term mating, appearance looms large for both sexes. Women care about looks in long-term choice too; many other traits simply rank above them.

What women want in the short term is still a live fight inside evolutionary psychology. The traditional answer, associated with Steve Gangestad, Martie Haselton, Randy Thornhill, and others, is that women go for cues to good genes in the short term and cues to resources in the long term. Markers of good genes in that literature include symmetrical features and masculine ones: a strong jaw, a high shoulder-to-hip ratio. Buss began to doubt the story because much of women's short-term mating is not one-night stands. It is affairs.

If the question is why women have affairs, the good-genes camp says: take genes from one man while keeping investment from the husband. The problem is that when women have affairs, more than 70 percent fall in love with or become attached to the affair partner. For men the figure is about 30 percent. From an engineering standpoint, if you are trying to keep one man's investment while secretly collecting better genes, falling in love is a disaster. "It's bad engineering," Buss says. He offers an alternative: the mate-switching hypothesis. Affairs are a way to leave a cost-inflicting partner, re-enter the market, or trade up. He puts his money on mate switching. His colleagues put theirs on good genes. He thinks the good-genes evidence is looking shakier than it first did.

Divorce and breakups occur in all cultures, so we are not especially good at lifelong monogamy. One issue is longevity: for more than 99 percent of evolutionary history people did not live to seventy or eighty, so we did not necessarily evolve to stay paired for decades. Long-term pair bonding is still a critical strategy. So is switching. If a partner becomes cost-inflicting, or is injured so badly that, in a hunter-gatherer world, he can no longer hunt or provision children, staying is a problem. Buss thinks we have adaptations to divest and trade up under certain conditions, and that those conditions differ for men and women.

Fridman, joking about "bro psychology forums," asks which muscle group matters. Buss points to a relatively high shoulder-to-hip ratio, physical fitness that is well toned but not muscle-bound—women do not, he says, find Mr. Olympia bodies attractive—and a height a bit above average, an inch or two over the local mean. Extreme body obsession can read as narcissism. Resources have always mattered to women: can he acquire them, and will he share them with her and the kids? In small-scale societies that often meant hunting skill. Steve Pinker's phrase, which Buss likes, is that people store meat in the bodies of other people: share when you succeed, collect when you fail. Cash economies, evolutionarily recent, let people stockpile wealth and explode inequality in a way ancestral life did not.

Fridman asks whether the objectification of bodies in media is a problem we should suppress, the way we try to suppress violence. Buss calls the modern flood an evolutionary mismatch. We evolved in small groups, comparing ourselves with a handful of real competitors. Social media bombards visual and mating psychology with thousands of images that are not representative of actual rivals: photographed, Photoshopped, highly selected. Baz Luhrmann's sunscreen speech had the line: do not read beauty magazines, they will only make you feel ugly. Buss thinks that is roughly true, and that the comparison process hurts women's self-esteem. In Western samples, male and female self-esteem start out similar; after puberty, women's drops as appearance becomes more important in mate competition.

The dishonesty may be the sharper problem than objectification as such. Studies originally associated with Paul Rozin, since replicated, show another distortion. Ask men their ideal female figure on a thin-to-plump scale and they pick the midpoint. Ask women their own ideal, and they pick thinner. Ask what they think men want, and they put it in the same thin spot as their own ideal. Women misperceive how thin men want them to be, a gap the fashion industry widens because clothes hang better on very thin models. Eating disorders such as anorexia and bulimia are nine to ten times more common in women than in men.

On gender as a pure social construct, Buss refuses a clean biology-versus-not split: biology is the study of life, and culture is something humans have an evolved capacity for. There are still universal psychological sex differences. One of the largest is the people-versus-things dimension—wanting work that involves social interaction versus mechanical objects or code—with an effect size of more than a standard deviation, in every culture. In the most gender-egalitarian countries, such as Sweden and Norway, some of these differences get larger when people have free occupational choice. The biggest sex differences sit in mating and sexuality, with a crucial asterisk: overlapping distributions, not male breasts versus female ones. Some women put all their weight on a man's looks; some men treat looks as irrelevant. Desire for sexual variety is a large, cross-cultural gap. Margaret Mead's Samoan men who painted their faces were not wearing makeup to look young and healthy. They were wearing war paint to look ferocious and mark a coalition. Same pigment, different function.

Status matters because it buys resources and influence. With Patrick Durkee, Buss mapped status criteria in fourteen cultures: trustworthiness, intelligence, wisdom, and knowledge look universal; some criteria are sex-differentiated and loop back into mating, because successful mating raises status and high status opens access to more desirable mates. Cash wealth is an infinitely fungible resource, recent in evolutionary time, which is why someone like Elon Musk can buy a media platform. Buss traces men's overrepresentation in power partly to women's mate preferences: over evolutionary time, preferring men with status and resources selected men to claw up hierarchies, even at the expense of friends and kin. He is not blaming women. He is describing co-evolution. Mating, he will not reduce civilization to "trying to get laid," but he thinks Ernest Becker's *Denial of Death* misses a sex difference: men more than women want a lasting legacy because it affects their lineage.

The Johnny Depp–Amber Heard defamation trial is in progress as they talk; Buss has not watched it, only read reports, and will not referee a relationship from years later. He has studied intimate partner violence, and he says the nastiness is sometimes asymmetrical and sometimes a downward spiral of insult and hitting that becomes symmetrical. Emotional instability—neuroticism, anxiety, lability—is the personality trait most predictive of breakups, divorce, and conflict. It can feel exciting. It is bad for long-term happiness. The Israeli biologist Amos Zahavi proposed that inflicting costs, even a kiss as a disease vector, can be a test of a bond: if you tolerate this, you must be committed. Buss's practical advice is to stress-test a serious relationship. Go on vacation, ideally to a foreign country, get a flat tire, and see how you treat each other when things go wrong.

Jealousy gets a whole book, *The Dangerous Passion*. Buss thinks it is a feature, not a bug: long-term pair bonding requires an adaptation sensitive to threats, because a desirable partner is still a target for poachers and for the partner's own dissatisfaction. Jealousy alerts you and motivates vigilance—in the modern world, that can mean phones, monitoring, even stalking, or it can mean upping attention and resources. Male sexual jealousy is also the leading cause of spousal abuse and a path to homicide. Buss has studied homicidal ideation aimed at people who poach, or successfully poach, a mate. A subtler trigger is a mate-value discrepancy: two sixes pair up, her career takes off, and jealousy fires even if she is loyal. People then either provision benefits or inflict costs. Both sexes, especially women, may read a total absence of jealousy as a lack of commitment. Sometimes they evoke it on purpose, another bond test.

Humans, Buss says, evolved as a pair-bonded species, which is not the same as lifelong monogamy. People pair-bond serially, have affairs, and do some short-term mating. They have a menu of strategies, constrained by mate value: an eight or a ten has options a one or two does not, including polyamory. Whether polyamory is actually rising or only more discussed is unclear. People in those relationships often describe jealousy as an emotion that has to be tamed, and they write explicit contracts—outside city limits, weeknights only, sex without emotional involvement—to keep it at bay. Put to a Sophie's choice, men are much more likely to say sexual infidelity would upset them more; about 85 percent of women say emotional infidelity is the worse blow. A former student's analysis of the show *Cheaters* found women asking "Are you in love with her?" and men asking whether sex had happened. The pattern has been replicated in Sweden and China.

With Cindy Meston, Buss catalogued 237 reasons humans have sex, from the obvious (it feels good, it relieves stress) to the petty (so he will take out the garbage) to the spiritual (to get closer to God) to revenge on a partner or a rival. Fantasies, unconstrained by norms, are a window into sexual psychology. Fetishes are overwhelmingly male, perhaps because early sexual experiences classically condition men to nearby cues. The evolutionary sketch is the investment asymmetry: a woman pays with pregnancy, a man can in principle reproduce from one act, so men are selected to be sexually conditionable to anything associated with sex. A woman in Austin, Buss says, could probably find a willing partner on Sixth Street in ten minutes. A man, unless he is Johnny Depp or extremely charming, would have a harder time.

About 80 percent of pornography consumers are men. Buss sees mixed effects. Men can acquire unrealistic expectations about bodies and sexual acrobatics—one unnamed husband, trained on enhanced breasts in porn, was disappointed by his wife's merely medium ones. Porn can also bleed off sexual energy that might have gone into real relationships, and some men spend hours a day on it, which Buss thinks can dull even ambition. Fridman adds that the metaverse's pleasures still miss rejection, growth, and the dance of an actual person. There is no replacement, Buss says, for exploring your sexuality with a real human being.

Asked about incels and a Wikipedia tally of mass murders linked to that subculture, Buss says sex and violence are linked in several ways, not only there. Ted Bundy, charming and not short of female attention, began his killing after rejection by a high-status woman; that is an n of one. Buss has not studied incel communities in detail, but an incoming graduate student has. His advice is blunt: many of the things women want—compassion, understanding, ambition, resources, fitness—are improvable. Raise your mate value instead of turning hostile toward women. Evolution, he adds, built in desires that can never be fully met. Men's desire for sexual variety is much greater than women's; unless you are a king with a harem, it makes men miserable. Hugh Grant, with Elizabeth Hurley, was still caught with a prostitute. That is the variety appetite, not a puzzle about Hurley's looks.

Each of sex, sex differences, and evolution is controversial; their intersection is especially so. Buss would rather be scientifically correct than politically correct. He has no political agenda beyond discovering human nature. Early in his career, after a talk in Michigan's sociology department, a female professor told him not to publish because women had it hard enough. He thinks suppression of knowledge about sex differences is naive and dangerous. Men and women are not psychological clones, especially in mating, sexuality, and violence—the more extreme the violence, the more it is a male monopoly. No one has tried to cancel him yet. He studies what is, not what ought to be, and he would prefer many of the findings not to be true. Sweden and Norway now have among the lowest homicide rates on earth; a few hundred years ago their ancestors were killing one another constantly. Like callus-producing skin, some mechanisms can sit quiet if the environment stops rubbing. Leaders, he notes more cynically, also exploit dehumanizing narratives to march people into atrocities.

Buss's advice to the young is not about careers. It is about mating, and he thinks high school should require a course on relationships—not the banana-and-condom hour, but how to select a mate, how to know you are in a bad one, and how to leave. The science is incomplete, but there are heuristics. In male-to-female partner violence, early warning signs include insisting on knowing her location at all times and cutting her off from friends and family. Women are most in danger of being killed by an ex in the first three to six months after a breakup; "meet me one last time" is a dangerous invitation. Mate with someone of similar mate value, and, harder, similar future trajectory. Compatibility on religion, politics, and values is not a luxury. Emotional instability will mean conflict; know what you are signing up for.

Internet dating expands the pool beyond friends of friends and bars. It also feeds the illusion that someone slightly more attractive and compatible is always one swipe away, a recipe for decision paralysis. Photos of face and body swamp every other cue, which is fine for a sex partner and a distortion for a long-term one. We evolved to respond to visual input, not to a bio that says "I like to go fishing." Fridman argues that screen appearance is not live appearance: wit, shyness, body language, and the weirdness of a person do not survive the profile. Buss's advice is simple. If you feel a connection, meet in real life. Stress-test it.

Love, after all that calculation, is an evolved emotion that helps solidify long-term pair bonds. The leading hypothesis is that it is a commitment device. Telling someone they exceed your thresholds on intelligence and looks is a terrible pickup line. "I love you," I cannot stop thinking about you, this feeling is not under control—that is a signal you will not dump an eight for an 8.5. Most humans have the capacity; culture can cloister it, as in some arranged-marriage systems. Historical China, Buss says, showed higher breakup and lower child production in arranged than in chosen marriages, though the pattern is not universal. He is not afraid of death. He is not eager to leave the party. His wife died prematurely of cancer; eight months of watching her die made mortality more familiar and less frightening. He likes Richard Dawkins's line that we are all going to die and we are the lucky ones, and Nabokov's image of life as a chink of light between two eternities of darkness.

What is the meaning of life? Fridman says love, in a wide sense, and creating beauty. Buss doubts any of this will mean anything in five billion years. In the meantime, meaning is the activation of a rich evolved psychology, most of which sits quiet at any moment: romantic love, friendship, being in a coalition, even the darker circuits. Men who have been through war often have a bond stronger than peacetime friendship. Studying homicidal ideation was, for him, as revealing as studying sexual fantasies. Asked whether they have ever thought of killing someone, 91 percent of men say yes and about 84 percent of women say no—until, ten minutes later, a story about public humiliation comes out. Mate poachers, infidelity, and status loss are predictable triggers. The joy of the science, and of a conversation like this one, is unlocking mechanisms that would otherwise stay dormant.