Sex At Dawn

Evolution and Human Nature

• Forget what you’ve heard about human beings having descended from the apes. We didn’t descend from apes. We are apes. Metaphorically and factually, Homo sapiens is one of the five surviving species of great apes, along with chimpanzees, bonobos, gorillas, and orangutans (gibbons are considered a “lesser ape”). We shared a common ancestor with two of these apes—bonobos and chimps—just five million years ago. That’s “the day before yesterday” in evolutionary terms.
• Evolutionary theory, in other words, offers explanations of how bodies came to be as they are.
• In his best-selling survey of EP, The Moral Animal, Robert Wright puts it succinctly, saying: “We are built to be effective animals, not happy ones. (Of course, we’re designed to pursue happiness; and the attainment of Darwinian goals—sex, status, and so on—often brings happiness, at least for a while.) Still, the frequent absence of happiness is what keeps us pursuing it, and thus makes us productive.”
• Genetically, the chimps and bonobos at the zoo are far closer to you and the other paying customers than they are to the gorillas, orangutans, monkeys, or anything else in a cage. Our DNA differs from that of chimps and bonobos by roughly 1.6 percent, making us closer to them than a dog is to a fox, a white-handed gibbon to a white-cheeked crested gibbon, an Indian elephant to an African elephant or, for any bird-watchers who may be tuning in, a red-eyed vireo to a white-eyed vireo.
• Evolutionary biologist Richard Dawkins, for example, might be a bit less certain in his gloomy assessment of human nature: “Be warned that if you wish, as I do, to build a society in which individuals cooperate generously and unselfishly towards a common good, you can expect little help from biological nature. Let us try to teach generosity and altruism, because we are born selfish.”10 Maybe, but cooperation runs deep in our species too.
• Human groups tend to respond to food surplus and storage with behavior like that observed in chimps: heightened hierarchical social organization, intergroup violence, territorial perimeter defense, and Machiavellian alliances. In other words, humans—like chimps—tend to fight when there’s something worth fighting over. But for most of prehistory, there was no food surplus to win or lose and no home base to defend.
• I sometimes try to imagine what would have happened if we’d known the bonobo first and chimpanzee only later or not at all. The discussion about human evolution might not revolve as much around violence, warfare, and male dominance, but rather around sexuality, empathy, caring, and cooperation. What a different intellectual landscape we would occupy! FRANS DE WAAL, Our Inner Ape
• Evolutionary theorists love to seek explanations for species’ most outstanding features: the elk’s antlers, the giraffe’s neck, the cheetah’s breakaway speed. These features reflect the environment in which the species evolved and the particular niche it occupies in this environment. What’s our species’s outstanding feature? Other than our super-sized male genitalia (see Part IV), we’re not very impressive from a physical perspective. With less than half our body weight, the average chimp has the strength of any four or five mustachioed firefighters. Plenty of animals can run faster, dive deeper, fight better, see farther, detect fainter smells, and hear tonal subtleties in what sounds like silence to us. So what do we bring to the party? What’s so special about human beings? Our endlessly complex interactions with each other. We know what you’re thinking: big brains. True, but our unique brains result from our chatty sociability. Though debate rages concerning precisely why the human brain grew so large so quickly, most would agree with anthropologist Terrence W. Deacon when he writes, “The human brain has been shaped by evolutionary processes that elaborated the capacities needed for language, and not just by a general demand for greater intelligence.” In a classic feedback loop, our big brains both serve our need for complex, subtle communication and result from it. Language, in turn, enables our deepest, most human feature: the ability to form and maintain a flexible, multidimensional, adaptive social network. Before and beyond anything else, human beings are the most social of all creatures. We have another quality that is especially human in addition to our disproportionately large brains and associated capacity for language. Perhaps unsurprisingly, it is also something woven into our all-important social fabric: our exaggerated sexuality.
• Think about that. No group-living nonhuman primate is monogamous, and adultery has been documented in every human culture studied—including those in which fornicators are routinely stoned to death. In light of all this bloody retribution, it’s hard to see how monogamy comes “naturally” to our species. Why would so many risk their reputations, families, careers—even presidential legacies—for something that runs against human nature? Were monogamy an ancient, evolved trait characteristic of our species, as the standard narrative insists, these ubiquitous transgressions would be infrequent and such horrible enforcement unnecessary. No creature needs to be threatened with death to act in accord with its own nature.
• Some species, in some conditions, have simply found that generosity is the best way to reduce risk in an uncertain ecological context. Homo sapiens appears to have been such a species until relatively recent times.
• It makes perfect Darwinian sense to suppose that prehistoric humans would choose the path that offered the best chance of survival—even if that path required egalitarian sharing of resources rather than the self-interested hoarding of resources many contemporary Western societies insist is basic human nature. After all, Darwin himself believed a tribe of cooperative people would vanquish one composed of selfish individualists. Are we preaching far-fetched flower-power silliness? Hardly. Egalitarianism is found in nearly all simple hunter-gatherer societies that have been studied anywhere in the world—groups facing conditions most similar to those our ancestors confronted 50,000 or 100,000 years ago. They’ve followed an egalitarian path not because they are particularly noble, but because it offers them the best chance of survival.
• Sarah Blaffer Hrdy, author of Mothers and Others, laments, “Infant-sharing in other primates and in various tribal societies has never been accorded center stage in the anthropological literature. Many people don’t even realize it goes on. Yet…the consequences of cooperative care—in terms of survival and biological fitness of mother and infant—turn out to be all to the good.”
• The holy grail of evolutionary psychology is the “human universal.” The whole point of the discipline is to tease out intrinsically human patterns of perception, cognition, and behavior from those determined on a cultural or personal level: Do you like baseball because you grew up watching games with Dad or because the sight of small groups of men strategizing and working together on a field connects to a primordial module in your brain? That’s the sort of question evolutionary psychologists love to ask and aspire to answer.
• Human nature is made of highly reflective material. It is a mirror—admittedly marked by unalterable genetic scratches and cracks—but a mirror nonetheless. For most human beings, reality is pretty much what we’re told it is. Like practically everything else, jealousy reflects social modification and can clearly be reduced to little more than a minor irritant if consensus deems it so.
• Yet most foragers don’t believe themselves to be impoverished, and there’s every indication that life wasn’t generally much of a struggle for our fire-controlling, highly intelligent ancestors bound together in cooperative bands. To be sure, occasional catastrophes such as droughts, climatic shifts, and volcanic eruptions were devastating. But most of our ancestors lived in a largely unpopulated world, chock-full of food. For hundreds of thousands of generations, the omnivore’s dilemma facing our ancestors lay in choosing among many culinary options. Plants eat soil; deer eat plants; cougars eat deer. But people can and do eat almost anything—including cougars, deer, plants, and yes, even soil.
• Richard Dawkins, author of The Selfish Gene, coined the term meme to refer to a unit of information that can spread through a community via learning or imitation the way a favored gene is replicated through reproduction.
• Were we really born in the best possible time and place? Or is ours a random moment in infinity—just another among uncountable moments, each with its compensating pleasures and disappointments? Perhaps you find it absurd to even entertain such a question, to assume there’s any choice in the matter. But there is. We all have a psychological tendency to view our own experience as standard, to see our community as The People, to believe—perhaps subconsciously—that we are the chosen ones, God is on our side, and our team deserves to win. To see the present in the most flattering light, we paint the past in blood-red hues of suffering and terror. Hobbes has been scratching this persistent psychological itch for several centuries now. It is a common mistake to assume that evolution is a process of improvement, that evolving organisms are progressing toward some final, perfected state. But they, and we, are not. An evolving society or organism simply adapts over the generations to changing conditions. While these modifications may be immediately beneficial, they are not really improvements because external conditions never stop shifting.
• Nonhuman primates offer intriguing evidence of the “soft power of peace”—and not just horny bonobos, either. Frans de Waal and Denise Johanowicz devised an experiment to see what would happen when two different macaque species were placed together for five months. Rhesus monkeys (Macaca mulatta) are aggressive and violent, while stump-tails (Macaca arctoides) are known for their more chilled-out approach to life. The stump-tails, for example, make up after conflict by gripping each other’s hips, whereas reconciliations are rarely witnessed among rhesus monkeys. Once the two species were placed together, however, the scientists saw that the more peaceful, conciliatory behavior of the stump-tails dominated the more aggressive rhesus attitudes. Gradually, the rhesus monkeys relaxed. As de Waal recounts, “Juveniles of the two species played together, groomed together, and slept in large, mixed huddles. Most importantly, the rhesus monkeys developed peacemaking skills on a par with those of their more tolerant group mates.” Even when the experiment concluded, and the two species were once again housed only with their own kind, the rhesus monkeys were still three times more likely to reconcile after conflict and groom their rivals.
• Sheldon Cohen and his colleagues studied the sleep habits of 153 healthy men and women for two weeks before putting them in quarantine and exposing them to rhinovirus, which causes the common cold. The less an individual slept, the more likely he or she was to come down with a cold. Those who slept less than seven hours per night were three times as likely to get sick.
• Just as eyeglasses have allowed survival and reproduction for people with visual incapacities that would have doomed them (and their genes) in ancestral environments, sexual monogamy permits fertility-reducing mutations to proliferate, causing testicular diminishments that would never have lasted among our nonmonogamous ancestors.
• The strongest explanation for the prevalence and intensity of the Coolidge effect among social mammals is that the male drive for sexual variety is evolution’s way of avoiding incest. Our species evolved on a sparsely populated planet—never more than a few million and probably fewer than 100,000 of us on Earth for most of our evolutionary past. To avoid the genetic stagnation that would have dragged our ancestors into extinction long ago, males evolved a strong appetite for sexual novelty and a robust aversion to the overly familiar. While this carrot-and-stick mechanism worked well to promote genetic diversity in the prehistoric environment, it’s causing lots of problems now. When a couple have been living together for years, when they’ve become family, this ancient anti-incest mechanism can effectively block eroticism for many men, leading to confusion and hurt feelings all around.

Sexual Behavior and Biology

• To see ourselves as we are, we must begin by acknowledging that of all Earth’s creatures, none is as urgently, creatively, and constantly sexual as Homo sapiens.
• Men offer goods and services (in prehistoric environments, primarily meat, shelter, protection, and status) in exchange for exclusive, relatively consistent sexual access. Helen Fisher called it The Sex Contract.
• This is how standard evolutionary theory posits that men evolved to be dirty, lying bastards. According to the standard narrative, the evolved behavioral strategy for a man is to cheat on his pregnant wife while being insanely—even violently—jealous of her. Charming. Although the survival odds of any children resulting from his casual encounters would presumably be lower than those of the children he helps raise, this investment would still be wise for him, given the low costs he incurs (a few drinks and a room at the Shady Grove Motor Lodge—at the hourly rate). The woman’s mixed strategy would be to extract a long-term commitment from the man who offers her the best access to resources, status, and protection, while still seeking the occasional fling with rugged dudes in leather jackets who offer genetic advantages her loving, but domesticated, mate lacks. It’s hard to decide who comes out looking worse.
• Various studies have demonstrated that women are more likely to cheat on their husbands (to have extra-pair copulations, or EPCs) when they are ovulating and less likely to use birth control than they are when not fertile. Furthermore, women are likely to wear more perfume and jewelry when ovulating than at other points in their menstrual cycle and to be attracted to more macho-looking men (those with physical markers of more vigorous genes).
• Either way, as depicted in the standard narrative, human sexual prehistory was characterized by deceit, disappointment, and despair. According to this view, both males and females are, by nature, liars, whores, and cheats. At our most basic levels, we’re told, heterosexual men and women have evolved to trick one another while selfishly pursuing zero-sum, mutually antagonistic genetic agendas—even though this demands the betrayal of the people we claim to love most sincerely. Original sin indeed.
• “the chimpanzee resolves sexual issues with power; the bonobo resolves power issues with sex.”
• And Fisher assures her readers that, like human beings, bonobos “walk arm in arm, kiss each other’s hands and feet, and embrace with long, deep, tongue-intruding French kisses.”
• Given the prominent role of chimpanzee behavior in supporting the standard narrative, how can we not include the equally relevant bonobo data in our conjectures concerning human prehistory? Remember, we are genetically equidistant from chimps and bonobos. And as Fisher notes, human sexual behavior has more in common with bonobos’ than with that of any other creature on Earth.
• Does all this frivolous sex make our species sound “animalistic”? It shouldn’t. The animal world is full of species that have sex only during widely spaced intervals when the female is ovulating. Only two species can do it week in and week out for nonreproductive reasons: one human, the other very humanlike. Sex for pleasure with various partners is therefore more “human” than animal. Strictly reproductive, once-in-a-blue-moon sex is more “animal” than human. In other words, an excessively horny monkey is acting “human,” while a man or woman uninterested in sex more than once or twice a year would be, strictly speaking, “acting like an animal.”
• Forget the billions pouring in from porn. Forget all the T&A on TV, in advertising, and in movies. Forget the love songs we sing on the way into relationships and the blues on the way out. Even if we include none of that, the percentage of our lives we human beings spend thinking about, planning, having, and remembering sex is incomparably greater than that of any other creature on the planet.
• Experts inadvertently encourage us to confuse the two. Helen Fisher’s Anatomy of Love, a book referenced earlier, is far more concerned with shared parental responsibility for a child’s first few years than with the love joining the parents to one another. But we can’t blame Fisher, as the language itself works against clarity. We can “sleep with” someone without ever closing our eyes.
• When we read that the politician “made love” with the prostitute, we know love had little to do with it. When we report how many “lovers” we’ve had, are we claiming to have been “in love” with all of them? Similarly, if we “mate” with someone, does that make us “mates”? Show a guy a photo of a hot-looking woman and ask him if he’d like to “mate with her.” Chances are good he’ll say (or think), “Sure!” But chances are also high that marriage, children, and the prospect of a long future together never entered into his decision-making process.
• We begin with body-size dimorphism. This technical-sounding term simply refers to the average difference in size between adult males and females in a given species. Among apes for example, male gorillas and orangutans average about twice the size of females, while male chimps, bonobos, and humans are from 10 to 20 percent bigger and heavier than females. Male and female gibbons are of equal stature. Among mammals generally and particularly among primates, body-size dimorphism is correlated with male competition over mating. In winner-take-all mating systems where males compete with each other over infrequent mating opportunities, the larger, stronger males tend to win…and take all. The biggest, baddest gorillas, for example, will pass genes for bigness and badness into the next generation, thus leading to ever bigger, badder male gorillas—until the increased size eventually runs into another factor limiting this growth. On the other hand, in species with little struggle over females, there is less biological imperative for the males to evolve larger, stronger bodies, so they generally don’t. That’s why the sexually monogamous gibbons are virtually identical in size.
• Along these same lines, women have also reported that their partners tend to be more vigorous in bed—reporting deeper, more vigorous thrusting—after a separation or if infidelity is suspected.
• Researchers have confirmed what porn producers already know: men tend to get turned on by images depicting an environment in which sperm competition is clearly at play (though few, we imagine, think of it in quite these terms). Images and videos showing one woman with multiple males are far more popular on the Internet and in commercial pornography than those depicting one male with multiple females.
• And despite all the bad press they get, men last far longer in the saddle than bonobos (fifteen seconds), chimps (seven seconds), or gorillas (sixty seconds), clocking in between four and seven minutes, on average.
• Frequent orgasm is associated with better cardiac health as well. A study conducted at the University of Bristol and Queen’s University of Belfast found that men who have three or more orgasms per week are 50 percent less likely to die from coronary heart disease.
• “Without sperm warfare during human evolution, men would have tiny genitals and produce few sperm…. There would be no thrusting during intercourse, no sex dreams or fantasies, no masturbation, and we would each feel like having intercourse only a dozen or so times in our entire lives…. Sex and society, art and literature—in fact, the whole of human culture—would be different.”
• 150 years after On the Origin of Species was published, isn’t it time to accept that our ancestors evolved along a sexual trajectory similar to that of our two highly social, very intelligent, closely related primate cousins? With any other question we have about the origins of human behavior, we look to chimps and bonobos for important clues: language, tool use, political alliances, war, reconciliation, altruism…but when it comes to sex, we prudishly turn away from these models to the distantly related, antisocial, low-I.Q. but monogamous gibbon? Really?
• Although many theories claim the human female has “hidden ovulation,” it’s not really hidden at all, if you know how and where to look. Martie Haselton and her colleagues found that men shown photographs of the same thirty women—some taken around ovulation and others not—were quite good at judging when the women were “trying to look more attractive,” which in turn corresponded to the women’s menstrual status. These authors found that women tend to dress more fetchingly when they are more likely to be fertile. “Moreover,” writes Haselton, “the closer women were to ovulation when photographed in the fertile window, the more frequently their fertile photograph was chosen.” Other researchers have found that men preferred women’s bodily smells near ovulation and that women tend to behave more provocatively in various ways when they’re likely to be fertile (they wear more jewelry and perfume, go out more, are more likely to hook up for casual sexual encounters, and are less likely to use condoms with new lovers).
• The human female’s sexual behavior is typically far more malleable than the male’s. Greater erotic plasticity leads most women to experience more variation in their sexuality than men typically do, and women’s sexual behavior is far more responsive to social pressure. This greater plasticity could manifest through changes in whom a woman wants, in how much she wants him/her/them, and in how she expresses her desire. Young males pass through a brief period in which their sexuality is like hot wax waiting to be imprinted, but the wax soon cools and solidifies, leaving the imprint for life. For females, the wax appears to stay soft and malleable throughout their lives.
• Every woman knows her menstrual cycle can have profound effects on her eroticism. Spanish researchers confirmed that women experience greater feelings of attractiveness and desire around ovulation, while others have reported that women find classically masculine faces more attractive around ovulation, opting for less chiseled-looking guys when not fertile. Since the birth control pill affects the menstrual cycle, it’s not surprising that it may affect a woman’s patterns of attraction as well. Scottish researcher Tony Little found women’s assessment of men as potential husband material shifted if they were on the pill. Little thinks the social consequences of his finding may be immense: “Where a woman chooses her partner while she is on the Pill, and then comes off it to have a child, her hormone-driven preferences have changed and she may find she is married to the wrong kind of man.”
• Psychologist Richard Lippa teamed up with the BBC to survey over 200,000 people of all ages from all over the world concerning the strength of their sex drive and how it affects their desires. He found the same inversion of male and female sexuality: for men, both gay and straight, higher sex drive increases the specificity of their sexual desire. In other words, a straight guy with a higher sex drive tends to be more focused on women, while higher sex drive in a gay guy makes him more intent on men. But with women—at least nominally straight women—the opposite occurs: the higher her sex drive, the more likely she’ll be attracted to men and women. Lesbians showed the same pattern as men: a higher sex drive means more women-only focus. Perhaps this explains why nearly twice as many women as men consider themselves bisexual, while only half as many consider themselves to be exclusively gay.
• Those who claim this just means men are more likely to be repressing some universal human bisexuality will have to consider sexologist Michael Bailey’s fMRI scans of gay and straight men’s brains while they viewed pornographic photos. They reacted as men tend to do: simply and directly. The gay guys liked the photos showing men with men, while the straight guys were into the photos featuring women. Bailey was looking for activation of the brain regions associated with inhibition, to see whether his subjects were denying a bisexual tendency. No dice. Neither gay nor straight men showed unusual activation of these regions while viewing the photos. Other experiments using subliminal images have generated similar results: gay men, straight men, and lesbians all responded as predicted by their stated sexual orientation, while nominally straight women (“I contain multitudes”) responded to just about everything. This is just how we’re wired, not the result of repression or denial.
• Recall Schopenhauer’s famous quote, “Mensch kann tun was er will; er kann aber nicht wollen was er will.” (One can choose what to do, but not what to want.) Desire, particularly male desire, is notoriously unresponsive to religious dictate, legal retribution, family pressure, self-preservation, or common sense. It does respond to one thing, however: testosterone.
• A 2005 survey of 12,000 adolescents found that those who had pledged to remain abstinent until marriage were more likely to have oral and anal sex than other teens, less likely to use condoms, and just as likely to contract sexually transmitted diseases as their unapologetically non-abstinent peers. The study’s authors found that 88 percent of those who pledged abstinence admitted to failing to keep their pledge.
• No, what makes heterosexual men seek a constant stream of different women doing the same old things is the Coolidge effect. If you’ve never been to a porn gateway website, you’ll be astounded by the variety and specificity of the offerings there: everything from “unshaved Japanese lesbians” to “tattooed redheads” to “overweight older gals.” It’s a simple, unavoidable truth almost everyone knows to be true but few dare to discuss: variety and change are the necessary spice of the sex life of the human male. But an intellectual understanding of this aspect of most men’s inner reality doesn’t make accepting it any easier for many women.
• Married men consistently show lower levels of the hormone than single men of the same age; fathers of young children, even less. Men who are particularly responsive to infants show declines of 30 percent or more right after their child is born. Married men having affairs, however, were found to have higher testosterone levels than those who weren’t. Additionally, most of the men having affairs have told researchers they were actually quite happy in their marriages, while only one-third of women having affairs felt that way.
• Indeed, quoting Symons, “A man’s sexual desire for a woman to whom he is not married is largely the result of her not being his wife.” Novelty itself is the attraction. Though they’re unlikely to admit it, the long-term partners of the sexiest Hollywood starlets are subject to the same psychosexual process. Frustrating? Unfair? Infuriating? Humiliating on both sides? Yes, yes, yes, and yes. But still, true.
• As their testosterone levels decline with age, many men experience a diminishment of energy and libido, an intangible distance from the basic pleasures of life. Most attribute this blurred distance to stress, lack of sleep, or too much responsibility, or they just chalk it up to the passage of time. True enough, but some of this numbing could be due to ebbing testosterone levels. Recall the man who had no testosterone for a while. He felt he’d lost “everything I identify as being me.” His ambition, passion for life, sense of humor…all gone. Until testosterone brought it all back. Without the testosterone, he said, “you have no desire.”
• How many men have mistaken this hormone high for a life-altering spiritual union? How many women have been blindsided by a good man’s seemingly inexplicable betrayal? How many families have been ripped apart because middle-aged men misinterpreted the surge of vitality and energy resulting from a novel sexual partner as love for a soul mate—or convinced themselves they were in love to justify what felt like a life-affirming necessity? And how many of these men then found themselves isolated, shamed, and devastated when the curse of Coolidge returned after a few months or years to reveal that the now-familiar partner was not, in fact, the true source of those feelings after all? No one knows the number, but it’s a big one.
• If it’s true that most men are constituted, by millions of years of evolution, to need occasional novel partners to maintain an active and vital sexuality throughout their lives, then what are we saying to men when we demand lifetime sexual monogamy? Must they choose between familial love and long-term sexual fulfillment? Most men don’t fully appreciate the conflict between the demands of society and those of their own biology until they’ve been married for years—plenty of time for life to have grown very complicated, with children, joint property, mutual friends, and the sort of love and friendship only shared history can bring. When they arrive at the crisis point, where domesticity and declining testosterone levels have drained the color from life, what to do?
• Having written this whole book about sex, we’d like to confusingly suggest that most of us take sex way too seriously: when it’s just sex, that’s all it is. In such cases, it’s not love. Or sin. Or pathology. Or a good reason to destroy an otherwise happy family.

Gender Differences

• Remember the Tenth Commandment: “Thou shalt not covet thy neighbour’s house, thou shalt not covet thy neighbour’s wife, nor his manservant, nor his maidservant, nor his ox, nor his ass, nor any thing that [is] thy neighbour’s.” Clearly, the biggest loser (aside from slaves, perhaps) in the agricultural revolution was the human female, who went from occupying a central, respected role in foraging societies to becoming another possession for a man to earn and defend, along with his house, slaves, and livestock.
• No doubt, males tend to be more concerned with a woman’s looks, while most women find a man’s character more compelling than his appearance (within limits, of course).
• Comedian Jerry Seinfeld sums it up in terms of fire and firemen: “The basic conflict between men and women, sexually, is that men are like firemen. To men, sex is an emergency, and no matter what we’re doing we can be ready in two minutes. Women, on the other hand, are like fire. They’re very exciting, but the conditions have to be exactly right for it to occur.”
• According to this theory, women have evolved to unthinkingly and unashamedly exchange erotic pleasure for access to a man’s wealth, protection, status, and other treasures likely to benefit her and her children. Darwin says your mother’s a whore. Simple as that.
• One of the most cited studies in all of evolutionary psychology, published by 1989, is typical of the genre.9 An attractive undergraduate student volunteer walked up to an unsuspecting student of the opposite sex (who was alone) on the campus of Florida State University and said, “Hi, I’ve been noticing you around town lately, and I find you very attractive. Would you go to bed with me tonight?” About 75 percent of the young men said yes. Many of those who didn’t asked for a “rain check.” But not one of the women approached by these attractive strangers accepted the offer. Case closed. Seriously, this study really is one of the best known in all of EP. Researchers reference it to establish that women aren’t interested in casual sex, which is important if your theory posits that women instinctively barter sex to get things from men. After all, if they’re giving it away for free, the bottom falls out of the market, and other women are going to have a harder time exchanging sex for anything of value.
• The evolutionary explanation for male sexual jealousy, as we’ve seen, pivots on the genetic calculus underlying paternity certainty. But if it’s a question of genes, a man should be far less concerned about his wife having sex with his brothers—who share half his genes—than with unrelated males. Gentlemen, would you be far less upset to find your wife in bed with your brother than with a total stranger? Ladies, would you prefer your husband have an affair with your sister? Didn’t think so.
• When it comes to sex, men may be trash-talking sprinters, but it’s the women who win all the marathons. Any marriage counselor will tell you the most common sex-related complaint women make about men is that they are too quick and too direct. Meanwhile, men’s most frequent sex-related gripe about women is that they take too damned long to get warmed up. After an orgasm, a woman may be anticipating a dozen more. A female body in motion tends to stay in motion. But men come and go. For them, the curtain falls quickly and the mind turns to unrelated matters.
• To have suggested that women enjoyed, indeed needed regular orgasmic release, would have been shocking to men and humiliating to most women. Perhaps it still is.
• This disconnect between what these women experienced on a physical level and what they consciously registered is precisely what the theory of differential erotic plasticity predicts. It could well be that the price of women’s greater erotic flexibility is more difficulty in knowing—and, depending on what cultural restrictions may be involved, in accepting—what they’re feeling. This is worth keeping in mind when considering why so many women report lack of interest in sex or difficulties in reaching orgasm.
• Researchers have found that men with lower levels of testosterone are more than four times as likely to suffer from clinical depression, fatal heart attacks, and cancer when compared to other men their age with higher testosterone levels. They are also more likely to develop Alzheimer’s disease and other forms of dementia, and have a far greater risk of dying prematurely from any cause (ranging from 88 to 250 percent higher, depending on the study).
• “I spoke to women who, on discovering that their husbands had cheated, immediately packed a bag and left, because ‘that’s what you do.’ Not because that’s what they wanted to do—they just thought that was the rule. They didn’t even seem to realize there were other options…. I mean, really, like they’re reading from a script!”

Modern Society vs Natural State

• Worldwide, pornography is reported to rake in anywhere from fifty-seven billion to a hundred billion dollars annually. In the United States, it generates more revenue than CBS, NBC, and ABC combined and more than all professional football, baseball, and basketball franchises.
• As long as population increases geometrically, doubling each generation (2, 4, 8, 16, 32, etc.), and farmers can increase the food supply only by adding acreage arithmetically (1, 2, 3, 4, etc.), there will never—can never—be enough for everyone. Thus, Malthus concluded that poverty is as inescapable as the wind and the rain. Nobody’s fault. Just the way it is. This conclusion was very popular with the wealthy and powerful, who were understandably eager to make sense of their good fortune and justify the suffering of the poor as an unavoidable fact of life.
• As German philosopher Arthur Schopenhauer pointed out, Mensch kann tun was er will; er kann aber nicht wollen was er will. (One can choose what to do, but not what to want.)
• Modern man’s seemingly instinctive impulse to control women’s sexuality is not an intrinsic feature of human nature. It is a response to specific historical socioeconomic conditions—conditions very different from those in which our species evolved. This is key to understanding sexuality in the modern world. De Waal is correct that this hierarchical, aggressive, and territorial behavior is of recent origin for our species. It is, as we’ll see, an adaptation to the social world that arose with agriculture.
• The story of the Fall gives narrative structure to the traumatic transition from the take-it-where-you-find-it hunter-gatherer existence to the arduous struggle of agriculturalists. Contending with insects, rodents, weather, and the reluctant Earth itself, farmers were forced to earn their bread by the sweat of their brow rather than just finding the now-forbidden fruit and eating it hand to mouth, as their ancestors had done forever. No wonder foragers have almost never shown any interest in learning farming techniques from Europeans. As one forager put it, “Why should we plant, when there are so many mongongo nuts in the world?”
• Agriculture, one might say, has involved the domestication of the human being as much as of any plant or other animal.
• What gets cultivated—in soil and minds—is not necessarily beneficial to the individuals in a given society. Something may benefit a culture overall, while being disastrous to the majority of the individual members of that society. Individuals suffer and die in wars from which a society may benefit greatly. Industrial poisons in the air and water, globalized trade accords, genetically modified crops…all are accepted by individuals likely to end up losing in the deal. This disconnect between individual and group interests helps explain why the shift to agriculture is normally spun as a great leap forward, despite the fact that it was actually a disaster for most of the individuals who endured it.
• Looking back from his overcrowded world, Thomas Hobbes imagined that prehistoric human life was unbearably solitary. Today, separated from countless strangers by only thin walls, tiny earphones, and hectic schedules, we assume a desolate sense of isolation must have weighed on our ancestors, wandering over their windswept prehistoric landscape. But in fact, this seemingly common-sense assumption couldn’t be more mistaken. The social lives of foragers are characterized by a depth and intensity of interaction few of us could imagine (or tolerate). For those of us born and raised in societies organized around the interlocking principles of individuality, personal space, and private property, it’s difficult to project our imaginations into those tightly woven societies where almost all space and property is communal, and identity is more collective than individual. From the first morning of birth to the final mourning of death, a forager’s life is one of intense, constant interaction, interrelation, and interdependence.
• Could it be that the atomic isolation of the husband-wife nucleus with an orbiting child or two is in fact a culturally imposed aberration for our species—as ill-suited to our evolved tendencies as corsets, chastity belts, and suits of armor? Dare we ask whether mothers, fathers, and children are all being shoe-horned into a family structure that suits none of us? Might the contemporary pandemics of fracturing families, parental exhaustion, and confused, resentful children be predictable consequences of what is, in truth, a distorted and distorting family structure inappropriate for our species?
• If the independent, isolated nuclear family unit is, in fact, the structure into which human beings most naturally configure themselves, why do contemporary societies and religions find it necessary to prop it up with tax breaks and supportive legislation while fiercely defending it from same-sex couples and others proposing to marry in supposedly “nontraditional” ways? One wonders, in fact, why marriage is a legal issue at all—apart from its relevance to immigration and property laws. Why would something so integral to human nature require such vigilant legal protection?
• Human beings will be happier—not when they cure cancer or get to Mars or eliminate racial prejudice or flush Lake Erie but when they find ways to inhabit primitive communities again. That’s my utopia. KURT VONNEGUT, JR.
• What constitutes misuse of the universe? This question can be answered in one word: greed…. Greed constitutes the most grievous wrong. LAURENTI MAGESA, African Religion: The Moral Traditions of Abundant Life
• We are enriched not by what we possess, but by what we can do without. IMMANUEL KANT
• A recent New York Times article under the headline “In Silicon Valley, Millionaires Who Don’t Feel Rich” begins, “By almost any definition—except his own and perhaps those of his neighbors here in Silicon Valley—Hal Steger has it made.” The article notes that although Mr. Steger and his wife have a net worth of roughly $3.5 million, he still typically works twelve-hour days plus another ten hours on weekends. “A few million,” explains Steger, “doesn’t go as far as it used to.” Gary Kremen (estimated net worth: $10 million), founder of Match.com, an online dating service, explains, “Everyone around here looks at the people above them.” He continues to work sixty to eighty hours per week because, he says, “You’re nobody here at $10 million.” Another executive gets right to the point, saying, “Here, the top 1 percent chases the top one-tenth of 1 percent, and the top one-tenth of 1 percent chases the top one-one-hundredth of 1 percent.” This sort of thinking isn’t limited to Silicon Valley. A BBC report from September 2003 reported, “Well-off is the new poor.” Dr. Clive Hamilton, a visiting scholar at Cambridge University, set out to study the “suffering rich” and found that four of every ten people earning over £50,000 (roughly $80,000 at the time) felt “deprived.” Hamilton concluded, “The real concerns of yesterday’s poor have become the imagined concerns of today’s rich.” Another recent survey in the United States found that 45 percent of those with a net worth (excluding their home) over $1 million were worried about running out of money before they died. Over one-third of those with more than $5 million had the same concern.
• “Nomadic habits, whether over wide plains, or through the dense forests of the tropics, or along the shores of the sea, have in every case been highly detrimental…. The perfect equality of all the inhabitants,” he wrote, “will for many years prevent their civilization.”
• Marvin Harris puts it simply: “Stone age populations lived healthier lives than did most of the people who came immediately after them.”
• For the vast majority of human generations that have ever lived, it would have been unthinkable to hoard food when those around you were hungry. “The hunter-gatherer,” writes Gowdy, “represents uneconomic man.”
• Ecologist Peter Turchin and anthropologist Andrey Korotayev looked at data from English, Chinese, and Roman history, finding strong statistical correlations between increases in population density and warfare. Their research suggests population growth could account for as much as 90 percent of the variation between historical periods of war and peace.
• Freedom (from war) is just another word for nothing to lose—or gain.
• If you want to live long, sleep more and eat less. To date, the only demonstrably effective method for prolonging mammalian life is severe caloric reduction. When pathologist Roy Walford fed mice about half of what they wanted to eat, they lived about twice as long—the equivalent of 160 human years. They not only lived longer, but stayed fitter and smarter as well (as judged by—you guessed it—running through mazes). Follow-up studies on insects, dogs, monkeys, and humans have confirmed the benefits of going through life hungry. Intermittent fasting was associated with more than a 40 percent reduction in heart disease risk in a study of 448 people published in the American Journal of Cardiology reporting that “most diseases, including cancer, diabetes and even neurodegenerative illnesses, are forestalled” by caloric reduction.
• To put it another way, if you hunt or gather just enough low-fat food to forestall serious hunger pangs, and spend the rest of your time in low-stress activities such as telling stories by the fire, taking extended hammock-embraced naps, and playing with children, you’d be engaged in the optimal lifestyle for human longevity.
• In Japan, there’s a word for it, karshi (): death from overwork. Japanese police records indicate that as many as 2,200 Japanese workers committed suicide in 2008 due to overwhelming work conditions, and five times that number died from stress-induced strokes and heart attacks, according to Rengo, a labor union federation. But whether our language contains a handy term for it or not, the devastating effects of chronic stress are not limited to Japan. Heart disease, circulatory problems, digestive disorders, insomnia, depression, sexual dysfunction, and obesity—behind every one of them lurks chronic stress. If we really did evolve in a Hobbesian ordeal of constant terror and anxiety, if our ancestors’ lives truly were solitary, poor, nasty, brutish, and short, why, then, are we still so vulnerable to stress?
• If prehistoric life was a perpetual struggle that ended in early death, if ours is a species motivated almost exclusively by self-interest, if war is an ancient, biologically embedded tendency, then one can soothingly argue, as Steven Pinker does, that things are getting better all the time—that, in his Panglossian view, “we are probably living in the most peaceful moment of our species’ time on Earth.” That would be encouraging news, indeed, which is what most audiences want to hear, after all. We all want to believe things are getting better, that our species is learning, growing, and prospering. Who refuses congratulations for having the good sense to be alive here and now? But just as “patriotism is the conviction that your country is superior to all others because you were born in it” (G. B. Shaw), the notion that we live in our species’ “most peaceful moment” is as intellectually baseless as it is emotionally comforting.
• The assertion that human beings are naturally monogamous is not just a lie; it’s a lie most Western societies insist we keep telling each other.
• Adolescents all over the country are getting into serious trouble for sexting one another: snapping a risqué photo of themselves with their cell phone and sending it to a friend. Turns out, in many states, these kids can be sent to prison (where sexual abuse is rampant) for photographing their own bodies (manufacturing child pornography) and sharing the photos (distributing child pornography). They’re being forced to register as sex offenders despite the fact that they themselves are the “victims” of their own “crimes.”

Relationships and Marriage

• In deference to Morgan’s scholarship, Darwin continued, “Those who have most closely studied the subject, and whose judgment is worth much more than mine, believe that communal marriage was the original and universal form throughout the world…. The indirect evidence in favour of this belief is extremely strong….” Indeed it is. And the evidence—both direct and indirect—has grown much stronger than Darwin, or even Morgan, could have imagined.
• Women and men should not marry, for love is like the seasons—it comes and goes. YANG ERCHE NAMU (Mosuo woman)
• Evolutionary biologist Richard Dawkins asks the pertinent question with characteristic elegance: “Is it so very obvious that you can’t love more than one person? We seem to manage it with parental love (parents are reproached if they don’t at least pretend to love all their children equally), love of books, of food, of wine (love of Château Margaux does not preclude love of a fine Hock, and we don’t feel unfaithful to the red when we dally with the white), love of composers, poets, holiday beaches, friends…why is erotic love the one exception that everybody instantly acknowledges without even thinking about it?”
• Once the transitory thrill passes, these men are left once again with the realities of what makes a relationship work over the long run: respect, admiration, convergent interests, good conversation, sense of humor, and so on. A marriage built upon sexual passion alone has as much chance of enduring as a house built on winter ice. Only by arriving at a more nuanced understanding of the nature of human sexuality will we learn to make smarter decisions about our long-term commitments. But this understanding requires us to face some uncomfortable facts.
• How many men think they have an “unspoken agreement” with their wife that, as long as she doesn’t find out about it, it’s okay for him to have a casual relationship on the side? This is like saying you have an unspoken agreement with the police that it’s okay to drive drunk—as long as they don’t catch you. Even if there is some understanding along these lines, any lawyer will tell you that unspoken agreements are the worst possible foundation for any long-term partnership.
• How is it “adult” to inflict emotional trauma on our children because we’re unable to face the truth about sex? Susan Squire, author of I Don’t: A Contrarian History of Marriage, asks: “Why does society consider it more moral for you to break up a marriage, go through a divorce, disrupt your children’s lives maybe forever, just to be able to fuck someone with whom the fucking is going to get just as boring as it was with the first person before long?”34 A man who pursues long-term happiness by leaving behind a string of hurt, embittered women and emotionally wounded children is little more than a dog chasing tail—his own.
• But in any true partnership—married or not—cheating cannot lead to any sort of victory. It’s win-win or everybody loses.
• Dan Savage explains, “The expectation of lifelong monogamy places an incredible strain on a marriage. But our concept of love and marriage has as its foundation not only the expectation of monogamy but the idea that where there’s love, monogamy should be easy and joyful.”
• Couples might find that the only route to preserving or rediscovering intensity reminiscent of their early days and nights requires confronting the open, uncertain sky together. They may find themselves having their most meaningful, intimate conversations if they dare to talk about the true nature of their feelings. We don’t mean to suggest these will be easy conversations. They won’t be. There are zones where it’s always going to be difficult for men and women to understand one another, and sexual desire is one of them. Many women will find it difficult to accept that men can so easily dissociate sexual pleasure from emotional intimacy, just as many men will struggle to understand why these two obviously separate (to them) issues are often so intertwined for many women.
• Despite what most mainstream therapists claim, for example, couples with “open marriages” generally rate their overall satisfaction (with both their relationship and with life in general) significantly higher than those in conventional marriages do.

Cultural Perspectives on Sex

• Every culture leads its members to believe some things are naturally right and others naturally wrong. These beliefs may feel right, but it’s a feeling we trust at our own peril.
• It appears Sigmund Freud got it right when he observed that “civilization” is built largely on erotic energy that has been blocked, concentrated, accumulated, and redirected.
• “To keep body and mind untainted,” explains Walter Houghton in The Victorian Frame of Mind, “the boy was taught to view women as objects of the greatest respect and even awe. He was to consider nice women (his sister and mother, his future bride) as creatures more like angels than human beings—an image wonderfully calculated not only to dissociate love from sex, but to turn love into worship, and worship of purity.” When not in the mood to worship the purity of his sisters, mother, daughters, and wife, men were expected to purge their lust with prostitutes, rather than threatening familial and social stability by “cheating” with “decent women.”
• Anthropologists Stephen Beckerman and Paul Valentine explain, “Pregnancy is viewed as a matter of degree, not clearly distinguished from gestation…all sexually active women are a little pregnant. Over time…semen accumulates in the womb, a fetus is formed, further acts of intercourse follow, and additional semen causes the fetus to grow more.” Were a woman to stop having sex when her periods stopped, people in these cultures believe the fetus would stop developing.
• As we write these words, CNN reports that six adulterers are being stoned to death in Iran. Before the hypocritical sinners throw the first stones, the male adulterers will be buried up to their waists. In a sickening gesture toward chivalry, the women will be buried to their necks, presumably to bring a quicker death to these women who dared consider their bodies their own. Such brutal execution of sexual transgressors is anything but an oddity, historically speaking. “Judaism, Christianity, Islam and Hinduism each share a fundamental concern over the punishment for a woman’s sexual freedom,” says Eric Michael Johnson. “Whereas any ‘man that committeth adultery with another man’s wife [both] the adulterer and the adulteress shall be put to death,’ (Leviticus 20:10) but any unmarried woman who has sexual relations with an unmarried man shall be brought ‘to the door of her father’s house, and the men of her city shall stone her with stones that she die’ (Deuteronomy 22:21).”
• Anthropologists William and Jean Crocker visited and studied the Canela people—also of the Brazilian Amazon region—for more than three decades, beginning in the late 1950s. They explain: It is difficult for members of a modern individualistic society to imagine the extent to which the Canela saw the group and the tribe as more important than the individual. Generosity and sharing was the ideal, while withholding was a social evil. Sharing possessions brought esteem. Sharing one’s body was a direct corollary. Desiring control over one’s goods and self was a form of stinginess. In this context, it is easy to understand why women chose to please men and why men chose to please women who expressed strong sexual needs. No one was so self-important that satisfying a fellow tribesman was less gratifying than personal gain [emphasis in original].
• According to anthropologist Robert Edgerton, the Marind-anim people of Melanesia believed: Semen was essential to human growth and development. They also married quite young, and to assure the bride’s fertility, she had to be filled with semen. On her wedding night, therefore, as many as ten members of her husband’s lineage had sexual intercourse with the bride, and if there were more men than this in the lineage, they had intercourse with her the following night…. A similar ritual was repeated at various intervals throughout a woman’s life.
• Much of this information comes from The Technology of Orgasm, Maines’s wonderful book on this “disease” and its treatment through the centuries.1 And what were the symptoms of this “disease”? Unsurprisingly, they were identical to those of sexual frustration and chronic arousal: “anxiety, sleeplessness, irritability, nervousness, erotic fantasy, sensations of heaviness in the abdomen, lower pelvic edema, and vaginal lubrication.” This supposed medical treatment for horny, frustrated women was not an isolated aberration confined to ancient history, but just one element in an ancient crusade to pathologize the demands of the female libido—a libido that experts have long insisted hardly exists.
• In 2003, seventeen-year-old honor student and homecoming king Genarlow Wilson was caught having consensual oral sex with his girlfriend, who had not yet turned sixteen. He was convicted of aggravated child molestation, sentenced to a minimum of ten years in a Georgia prison, and forced to register as a sex offender for life. If Wilson and his girlfriend had just enjoyed good old-fashioned intercourse, as opposed to oral sex, their “crime” would have been a misdemeanor, punishable by a maximum of a year in prison and no sex-offender status.
• Prescott concluded that in all but one of the cultures for which these data were available (forty-eight of forty-nine), “deprivation of body pleasure throughout life—but particularly during the formative periods of infancy, childhood, and adolescence—is very closely related to the amount of warfare and interpersonal violence.” Cultures that don’t interfere in the physical bonding between mother and child or prohibit the expression of adolescent sexuality show far lower levels of violence—both between individuals and between societies.
• Yes, sex is essential, but it’s not something that must always be taken so seriously. Think of food, water, oxygen, shelter, and all the other elements of life crucial to survival and happiness but that don’t figure in our day-to-day thinking unless they become unavailable. A reasonable relaxation of moralistic social codes making sexual satisfaction more easily available would also make it less problematic.

Reproductive Science

• More recently, several researchers have demonstrated that a man’s sperm production increases significantly when he has not seen his partner for a few days, regardless of whether or not he ejaculated during her absence. This finding conforms to the notion that sperm competition has played a role in human evolution
• One researcher suggests that average sperm counts in Danish men have plummeted from 113 × 106 in 1940 to about half that in 1990 (66 × 106).5 The list of potential causes for the collapse is long, ranging from estrogen-like compounds in soybeans and the milk of pregnant cows to pesticides, fertilizers, growth hormones in cattle, and chemicals used in plastics.
• The Human Reproduction study at the University of Rochester found that men whose mothers had eaten beef more than seven times per week while pregnant were three times more likely to be classified as subfertile (fewer than twenty million sperm per milliliter of seminal fluid). Among these sons of beef eaters, the rate of subfertility was 17.7 percent, as opposed to 5.7 percent among men whose mothers ate beef less often.
• The correlation between infrequent ejaculation and various health problems offers further evidence that present-day men are not using their reproductive equipment to its fullest potential. A team of Australian researchers, for example, found that men who had ejaculated more than five times per week between the ages of twenty and fifty were one-third less likely to develop prostate cancer later in life.
• The idea that female choice (conscious or not) can happen after or during intercourse rather than as part of an elaborate precopulatory courtship ritual turns the standard narrative inside out and upside down. If the female’s reproductive system has evolved intricate mechanisms for filtering and rejecting the sperm cells of some men while helping along those of a man who meets criteria of which she may be utterly unaware, Darwin’s “coy female” starts looking like what she is: an anachronistic male fantasy.
• In addition to enveloping eggs, a cervix that filters or favors sperm, and vaginal contractions that may expel the sperm of one man while boosting that of another, women’s orgasms provoke changes in vaginal acidity. These changes appear to assist the sperm cells of the lucky guy who provoked the orgasm.
• Consider the implications. Many couples meet when the woman is on the pill. They go out for a while, like each other a lot, and then decide to get together and have a family. She goes off the pill, gets pregnant, and has a baby. But her response to him changes. There’s something about him she finds irritating—something she hadn’t noticed before. Maybe she finds him sexually unattractive, and the distance between them grows. But her libido is fine. She gets flushed every time she gets close enough to smell her tennis coach. Her body, no longer silenced by the effects of the pill, may now be telling her that her husband (still the great guy she married) isn’t a good genetic match for her. But it’s too late. They blame it on the work pressure, the stress of parenthood, each other…. Because this couple inadvertently short-circuited an important test of biological compatibility, their children may face significant health risks ranging from reduced birth weight to impaired immune function. How many couples in this situation blame themselves for having “failed” somehow? How many families are fractured by this common, tragic, undetected sequence of events?

Social Organization and Community

• If you ever doubt that human beings are, beyond everything, social animals, consider that short of outright execution or physical torture, the worst punishment in any society’s arsenal has always been exile. Having run short of empty places to exile our worst prisoners, we’ve turned to internal exile as our harshest punishment: solitary confinement. Sartre got it backwards when he proclaimed, “L’enfer, c’est les autres” (Hell is other people). It’s the absence of other people that is hellish for our species. Human beings are so desperate for social contact that prisoners almost universally choose the company of murderous lunatics over extended isolation.
• For professional athletes, musicians, and their most enthusiastic female fans, as well as both male and female members of many foraging societies, overlapping, intersecting sexual relationships strengthen group cohesion and can offer a measure of security in an uncertain world. Sometimes, perhaps most of the time, human sex isn’t just about pleasure or reproduction. A casual approach to sexual relationships in a community of adults can have important social functions, extending far beyond mere physical gratification.
• Some anthropologists question whether kinship is an important concept in band-level societies at all—however defined. They argue that since everyone in such a small-scale society is likely to be related to each other in some way, affinity tends to be measured in more fluid terms, such as friendship and sharing partners.
• Among foragers, where property is shared, poverty tends to be a nonissue. In his classic book Stone Age Economics, anthropologist Marshall Sahlins explains that “the world’s most primitive people have few possessions, but they are not poor. Poverty is not a certain small amount of goods, nor is it just a relation between means and ends; above all it is a relation between people. Poverty is a social status.
• Well into the 1800s, much of rural England was considered commons—property owned by the king but available to everyone—like the open range in the western United States before the advent of barbed-wire fencing. Using the English commons as his model, Hardin purported to show what happens when a resource is communally owned. He reasoned that in “a pasture open to all…each herdsman will try to keep as many cattle as possible.” Though destructive to the pasture, the herdsman’s selfishness makes good economic sense from his personal perspective. Hardin wrote, “The rational herdsman [will conclude] that the only sensible course for him to pursue is to add another animal to his herd.” This is the only rational choice because all will share the cost of the degradation to the land from overgrazing, while the profit gained from additional animals will be his alone. Since each individual herdsman will come to the same conclusion, the common ground will inevitably be overgrazed. “Freedom in a commons,” Hardin concluded, “brings ruin to us all.”
• One other thing Hardin’s elegant argument has in common with that of Malthus: it collapses on contact with reality. As Canadian author Ian Angus explains, “Hardin simply ignored what actually happens in a real commons: self regulation by the communities involved.” Hardin missed the fact that in small rural communities where population density is low enough that each of the herdsmen knows the others (the actual case in the historical English commons and in ancestral foraging societies), any individual who tries to game the system is quickly found out and punished. Nobel Prize–winning economist Elinor Ostrom’s studies of commons management in small-scale communities led her to conclude that, “all communities have some form of monitoring to gird against cheating or using more than a fair share of the resource.” Despite how it’s been spun by economists and others arguing against local resource management, the real tragedy of the commons doesn’t pose a threat to resources controlled by small groups of interdependent individuals.
• These tragedies become inevitable only when the group size exceeds our species’ capacity for keeping track of one another, a point that’s come to be known as Dunbar’s number. In primate communities, size definitely matters. Noticing the importance of grooming behavior in social primates, British anthropologist Robin Dunbar plotted overall group size against the neocortical development of the brain. Using this correlation, he predicted that humans start losing track of who’s doing what to whom when group size hits about 150 individuals. In Dunbar’s words, “The limit imposed by neocortical processing capacity is simply on the number of individuals with whom a stable inter-personal relationship can be maintained.” Other anthropologists had arrived at the same number by observing that when group sizes grew much beyond that, they tend to split into two smaller groups. Writing several years before Dunbar’s paper was published in 1992, Marvin Harris noted, “With 50 people per band or 150 per village, everybody knew everybody else intimately, so that the bonding of reciprocal exchange could hold people together. People gave with the expectation of taking and took with the expectation of giving.” Recent authors, including Malcolm Gladwell in his best-selling The Tipping Point, have popularized the idea of 150 being a limit to organically functioning groups.
• Having evolved in small, intimate bands where everybody knows our name, human beings aren’t very good at dealing with the dubious freedoms conferred by anonymity. When communities grow beyond the point where every individual has at least a passing acquaintance with everyone else, our behavior changes, our choices shift, and our sense of the possible and of the acceptable grows ever more abstract. The same argument can be made concerning the tragic misunderstanding of human nature that underlies communism: community ownership doesn’t work in large-scale societies where people operate in anonymity.
• research conducted by sociologist Patrick Nolan, who found, “Warfare is more likely in advanced horticultural and agrarian societies than it is in hunting-and-gathering and simple horticultural societies.” When he limited his analysis only to hunter-gatherer and agrarian societies, Nolan found that above-average population density was the best predictor of war.
• Early agriculture’s stores of harvested grain and herds of placid livestock were like boxes of bananas in the jungle. There was now something worth fighting over: more. More land to cultivate. More women to increase population to work the land, raise armies to defend it, and help with the harvest. More slaves for the hard labor of planting, harvesting, and fighting. Failed crops in one area would lead desperate farmers to raid neighbors, who would retaliate, and so on, over and over.