Figure 8.1. Survival rates among different groups of chimpanzees and human foragers. (Adapted from Wood et al., 2017, by Gwendolyn David)
EVOLUTIONARY PSYCHOLOGY AND WORLD PEACE
We are incredibly fortunate to live in a time of increasing peace and diminishing interpersonal violence. It may not feel like it if you keep up with the news, but over the last thousand years, hundred years, and even twenty-five years, violence has decreased across the industrialized world. There are many reasons for this fortunate state of affairs, as the establishment of democracy, strong institutions of government, international trade and tourism, and numerous other factors have contributed to our greater understanding of one another and a more peaceful world.
Decreased interpersonal (as opposed to interstate) violence is largely a product of two factors. First, the presence of strong and relatively impartial law enforcement has undermined the three main sources of violence identified by the great political philosopher Thomas Hobbes. In the presence of a strong and impartial state, I’m no longer motivated to attack you to take what’s yours, as I know that the state will punish me. It’s also no longer necessary to attack you to prevent you from taking what’s mine, because, again, I know the state will protect me. And finally, I no longer need to retaliate if you attack me or my family, as I know the state will punish you.
Second, and more speculatively, as the industrialized world has become a safer place, those of us who are fortunate to live in it have become more sensitized to violence. Increases in safety happen slowly, so we tend not to notice them, but over a long enough time span, the effects are dramatic. The biggest difference, of course, is that between hunter-gatherers and people who have access to modern medicine. Consider the survival curves depicted in Figure 8.1 documented by Brian Wood of Yale University and his colleagues, showing chimpanzees in different parts of Africa and humans from different foraging societies.
Figure 8.1. Survival rates among different groups of chimpanzees and human foragers. (Adapted from Wood et al., 2017, by Gwendolyn David)
As is evident in the left panel, nearly half the chimps born across these various groups die before the age of five (which is still childhood for a chimp). Rather remarkably, the survival rates aren’t that much better for humans: 20 to 40 percent of human children also die by age five (right panel). If we consider twenty years old to be the beginning of adulthood in humans, we see that 25 to 50 percent of humans across these societies never reach adulthood. High levels of violence in forager societies contribute to the high mortality rate, but the high mortality rate undoubtedly contributes to the violence as well. When people become inured to suffering, the harms they cause each other seem less significant.
It is no surprise that our lives have become much safer than when we were hunter-gatherers, but changes in safety are also substantial in modern environments. Figure 8.2 depicts changes in mortality rates during childbirth for mothers and during the first five years of life for children in the United States across the twentieth century. As is evident in these data, childbirth and childhood have become dramatically safer. In the early 1900s, nearly 1 percent of mothers died in each delivery. Even more remarkably, almost 25 percent of children died before the age of five (a rate equivalent to those of some of the hunter-gatherer groups depicted in Figure 8.1). In such a world, everyone knew someone who died from complications in delivery and who lost children before their fifth birthday.
Figure 8.2. Maternal (left) and child (right) mortality rates in the United States. (Our World in Data)
Numerous other advances in health mirror these positive trends. For example, at the start of the twentieth century, 120 out of every 100,000 people in the United Kingdom died of food poisoning each year. To put this number in perspective, it was more dangerous to go out for fish and chips in Oxford in 1890 than it was to hang out in downtown Detroit a hundred years later. Similar statistics can be found for numerous other threats to health and longevity, and many didn’t abate until very recently.
Perhaps these increases in health are unsurprising, as modern medicine has been such a success story. But other data show that changes in safety are not just a function of medical advances—people’s behavior toward each other has also changed. For example, we can see big drops in the homicide rate across America’s five largest cities (New York, Los Angeles, Chicago, Houston, and Philadelphia) over the last thirty years. In the late 1980s to early ’90s, these cities all suffered an average of about 30 homicides per 100,000 citizens per year. By 2015, New York and LA were at less than a third of their prior homicide rate, Houston and Philadelphia had cut their earlier rate by half, and only Chicago’s recent rise in crime resulted in murder rates that are anywhere near what we saw in the ’90s. These data show that living in big American cities has become much safer in just the last thirty years.
Murderers may not be like everyone else, so you could reasonably argue that these data don’t speak to widespread behavioral change. For evidence of widespread change, drunk driving is one of the best examples. As recently as the late ’70s, drunk driving was not only commonplace but perceived as an unavoidable fact of life. Perhaps the most remarkable thing was that people treated it like a joke. When someone had too much to drink at a party, their friends would go so far as to help them insert the key in the ignition and then laughingly watch them lurch off down the road. In Fear and Loathing in Las Vegas, Hunter S. Thompson describes how a police officer let him drive home to sleep it off when he was clearly intoxicated behind the wheel. That event may or may not have actually happened, but it seemed perfectly plausible at the time.
Everything changed with the advent of Mothers Against Drunk Driving in 1980, which can be credited with drawing awareness to the (admittedly obvious) fact that drunk drivers hurt people other than themselves. Since 1982, when DUI statistics were first recorded (a remarkable fact in itself), drunk-driving deaths in the United States have dropped from more than twenty thousand per year to under ten thousand. This improvement is all the more noteworthy when you consider that Americans have doubled the number of miles they drive since 1982, suggesting that four times as many drunk drivers were on the road in 1980 as there are today.
Along with these massive changes in safety came massive changes in attitudes. My favorite example of how much attitudes have changed took place when I was on my way home from kindergarten in 1969. My friend Andy’s father, a police officer, happened to be driving our carpool that day. There were four or five of us sitting in the backseat of his car, and none of us had seat belts on because cars were rarely equipped with seat belts in those days. As we rounded a corner a few blocks from my house, all the children slid across the bench seat and pressed against me. I tried to push back, but they were too heavy and I was pressed against the door. The next thing I knew, the door flew open and I was bouncing across the road and into a ditch. Andy’s dad stopped the car to retrieve me—no surprise there; he could hardly have arrived at my house empty-handed—but what might seem surprising was my mother’s reaction when he brought me home.
Take a moment to consider how you would react if a friend were driving your five-year-old home from school and showed up with the embarrassing admission that your child had fallen out of the moving vehicle and rolled across the street. Even if your friend quickly added the good news that none of the subsequent vehicles ran your child over, you’d probably be horrified and nearly speechless.
In contrast, my mother looked over my bumps, cuts, and scrapes and told Andy’s dad that I seemed fine and not to worry about it; these things happen. Lest you think my mother was callous and uncaring, when my friend’s brother fell out of his family car under similar circumstances, his mother berated him for not holding on more tightly. This is the world we lived in not so long ago. Drunk drivers were an amusing nuisance, no one wore seat belts (or even imagined a world of children in car seats), and everyone was fine with that.
In such a context, homicide or assault would have been a tragedy for the victim’s family and friends, but to everyone else such crimes were an almost unnoticeable blip against a background of so much death and mayhem. As time passes and we become accustomed to food that doesn’t kill us; seat belts, shatterproof windshields, and airbags that protect us; and dogs that don’t bite us (because they no longer roam neighborhoods freely), each individual incident begins to stand out in sharper relief.
Opponents of violent TV and violent video games argue that these forms of pseudo-violence inure us to the real thing, but I think the negative effects of violent entertainment are dwarfed by the increasingly safe world in which we reside. There is no doubt that the internet allows us to see real carnage whenever and wherever it occurs in the world, and I’m sure that this contributes to our sense that the world is more dangerous than it was when we were younger. But our everyday experience is one of safety, and I suspect that our softened sensibilities have played a self-perpetuating role in making people less likely to commit murder, rape, and assault over the last few decades.
The increasing safety and decreasing violence that we see within industrialized countries have been mirrored by decreasing levels of conflict between countries as well. Nevertheless, there are constant threats to global security: conflicts in Europe, the Middle East, and Africa frequently escalate; terrorist groups such as Islamic State seek to inflame religious tensions; many countries are nostalgic for a time when they wielded a larger influence on the world stage, and make territorial claims that are inconsistent with the current international order; and, perhaps most surprising of all, xenophobic politicians show enduring (and at the time of this writing, increasing) popularity even in wealthy and stable countries. For these reasons, international peace and security cannot be taken for granted. The remainder of this chapter outlines how our evolved psychology contributes to this tenuous state of peace on the planet.
Humans Evolved to Cooperate within but Not between Groups
Chapter 1 discusses how we survived and thrived on the savannah by learning to be much more cooperative than our chimpanzee cousins. In principle, cooperation has the potential to make us more peaceful, but it turns out that our cooperation is highly selective; we evolved to cooperate with our fellow group members, but not with members of other groups. The reason for this state of affairs is that in our ancestral past, other groups were a toss-up: sometimes an opportunity and sometimes a threat. When encounters with other groups proved to be friendly, our ancestors increased their mating opportunities (and decreased inbreeding) by finding partners in other groups. But encounters often proved to be unfriendly, as sometimes members of other groups wanted what we had and chose to take it by force.
Stone throwing dramatically increased our safety on the savannah, but it also opened up an entirely new threat: the power to kill at a distance marked the beginning of highly effective warfare. Once we gained the ability to engage in collective stoning, we also gained the ability to engage in pitched battles. When Homo erectus doubled down on that capacity and developed planning and division of labor, strategizing and military campaigns became possible. As a consequence, the selective cooperation only with members of our own group was a prudent choice for our ancestors, as other groups rapidly became our most dangerous competitors. Once our ancestors moved to the top of the food chain, the risks posed by other animals rapidly diminished, and humans soon became their own greatest threat.
As I discuss in chapter 7, people in small-scale societies are often in a state of conflict with other groups. Such conflicts typically manifest themselves in skirmishes and raids rather than the pitched battles we associate with warfare between industrialized nations. But skirmishes and raids are also deadly, particularly over the long term, and members of successful war parties benefit from their violence through the theft of transportable wealth such as cattle and the opportunity to gain additional wives in the form of captured women. Intergroup conflict has thus been sustained in part because it can lead to greater reproductive success for members of successful war parties.
In addition to the competition for resources posed by members of other groups, our ancestors also faced the risk that other groups had been exposed to different pathogens, and thus could potentially give them new diseases. In a premedical world, the threat of disease was much greater than it is today, so we developed psychological adaptations to disease threats that are collectively characterized as the behavioral immune system. Our biological immune system deals with pathogens once we have ingested them (e.g., by vomiting them out or finding and destroying them), but our behavioral immune system evolved to prevent us from ingesting pathogens in the first place. For example, feces, open sores, infections, and vomit are rife with pathogens, so we evolved to find the sight and smell of them disgusting and to avoid them. People who found other people’s open sores interesting or attractive were far less likely to survive and have children of their own, and thus evolution ensured that our disgust protected us.
Pathogens vary a lot in their virulence, and our psychology is fine-tuned to avoid those germs that are the greatest threat to us. By way of example, consider the following thought experiment. Imagine that you’re on an airplane and standing in line to use the toilet. When your turn arrives, you notice that the person exiting the bathroom has a rather sheepish expression. You go inside and raise the toilet lid, and the cause of his expression immediately becomes obvious: evidence of his gastrointestinal distress is everywhere.
Here’s the question: would this situation be more disgusting if the guy with tummy trouble were your brother or the random stranger seated in 21C? Most people find the scenario more revolting if the culprit is from 21C. And there’s good reason for this: a stranger’s feces are much more likely to make you sick than your brother’s feces. You have far greater prior exposure to your brother’s germs than to a stranger’s, so you are more likely to have developed immunities to them.
A version of this thought experiment has even been run with actual poo, and the results are as predicted. The intrepid Trevor Case of Macquarie University and his colleagues conducted a study in which they asked mothers of young babies to come into the lab with their child’s poopy diapers. The researchers separated the poo into containers and then asked the mothers to sniff them. The mothers were incapable of detecting which poo came from which baby, but they found the smell of the other babies’ poo more disgusting than that of their own baby. Even though mothers were unable to identify their baby’s poo, at an unconscious level their behavioral immune system pushed them away from the feces with a higher level of unfamiliar pathogens.
Experiments such as these point to the exquisite sensitivity of the behavioral immune system, and our evolved capacity to avoid germs that are most likely to make us sick. We see additional evidence for these processes in the geographic distribution of languages, religions, and ethnocentrism. As we move from the poles to the equator, the number of languages and religions per region increases, and people become more xenophobic. These effects may seem to be unrelated, but all three processes serve to keep groups apart. When you don’t speak the same language, when you don’t share a religion, and when you tend to dislike members of other groups, you’re much less likely to intermingle with them.
Why would languages and religions proliferate around the equator, and why is their frequency also related to ethnocentrism? The answer to these questions lies in the fact that pathogen density is much higher in the tropics than it is in temperate and cold climates. When you live in Sweden, chances are good that any group within five hundred miles has been exposed to the same few pathogens. In contrast, when you live in the Congo, the group on the other side of the valley may well have been exposed to a pathogen with which you’ve had no prior contact.
For this reason, humans in the tropics learned that when they interacted with other groups they tended to get sick, so they would have stopped doing it. In a pre-scientific world, it was logical to blame their neighbors for their illness (which was partially true, at any rate), and therefore to dislike them. Dislike and fear kept neighbors apart, and once you don’t interact with others anymore, your languages and religions naturally diverge as well. All these processes are self-perpetuating and serve to further group separation.
The effects of pathogens on attitudes, behaviors, and beliefs that keep groups apart also tend to be stronger when the pathogens rely on human-to-human transmission (e.g., hepatitis) than when they are transmitted from animals to humans (e.g., malaria). When other people engage in cultural practices that differ from our own, their behaviors not only call into question our cultural or religious practices, but also have the potential to lead to different routes of disease transmission. Different ways of cooking, different rites of passage, and different mating systems can lead to new forms of pathogen exposure. Our behavioral immune system evolved to ensure that such foreign practices seemed not just different to us, but also wrong.
Although our attitudes evolved to help protect us from illness, the attitudes that make up the behavioral immune system aren’t directed at the germs themselves. Rather, these attitudes simply caused us to avoid dangerous pathogens, the sources of which we didn’t understand when the attitudes were evolving. For example, by regarding behaviors different from our own as wrong or immoral, we tend to stay away from people who engage in those behaviors, which protects us from them.
Because humans tend to moralize behaviors that play an important role in procreation and disease transmission (which are often the same behaviors), merely different ways of doing things rapidly become immoral ways of doing things if they have the potential to serve as a disease vector. It is thus likely that pathogen threats are an underlying source of what is known as symbolic prejudice, or the animosity toward groups with different practices and beliefs from our own. Once other groups are perceived as immoral, people are much more likely to avoid each other, and when they do come in contact, conflict is much more likely to ensue.
For all these reasons, we evolved to cooperate with members of our own group, but not with members of other groups. This tribalism is often perceived as inconsistent with our cooperative nature, but our evolutionary history reveals that they are in fact two sides of the same coin. Our tribalism is actually cause and consequence of our cooperative nature, as our capacity to care for members of our own group evolved to make us more effective killers.
Evidence for our selective, within-group cooperation can be found in numerous places, but perhaps the clearest distinction is the one between humans and chimpanzees. To obtain an indicator of our historical rates of conflict, Richard Wrangham of Harvard University examined levels of physical conflict among human hunter-gatherer populations. Because they have no recourse to formal laws or police, hunter-gatherers provide the best indication of what our species level of violence was like before the advent of modern government. When Wrangham compared the level of within-group conflict among hunter-gatherers to that of chimpanzees, he found that chimpanzees were 150 to 550 times more likely than humans to resort to physical aggression within their groups. In contrast, when he examined acts of between-group aggression and violence, he found that rates of violence are basically the same across human foragers and chimpanzees. Our move to the savannah made us much nicer to each other, but this effect doesn’t translate across group boundaries.
Despite these evolutionary changes, conflict and competition remain rife within groups, as people often fight over resources or disagree about how to solve communal problems. Sexual selection creates the most important challenge to within-group cooperation, as everyone is motivated to increase their status relative to other members of their group. These are the reasons hunter-gatherer groups are often overcome with bickering when they become larger than twenty or thirty individuals. Nonetheless, the threat posed by other groups was a substantial countervailing force to conflict within groups. The predilection to cooperate with each other when threatened by other groups was critical to our survival, as between-group competition was an existential threat whereas within-group competition was merely a status threat.
These competing aspects of our evolved psychology continue to manifest themselves in important ways in national and international relations. Perhaps most notably, cooperation within groups can dissolve over time in the absence of an external threat. The extreme partisanship and toxic political climate in the United States have been explained in many ways, but from an evolutionary perspective, part of the underlying cause is the demise of the Soviet Union. Conflict between political parties was once set aside at the nation’s border because internal conflicts were less important than maintaining unity in the face of a powerful enemy. The fall of the Soviet Union marked the end of the only real existential threat to the United States, with the consequence that internal conflicts are now less likely to be held in check. Without the countervailing threat of a sufficiently powerful external enemy, the political parties increasingly see their greatest obstacles not in the actions of other countries, but in the competing goals and preferences of their domestic rivals.
The impact of external threats can easily be seen in Figure 8.3, which depicts how rapidly Americans came together in their support of President Bush after the attacks of September 11, 2001. Figure 8.3 also shows how that surge in support slowly dissipated as the threat came to be seen as less imminent, and then spiked again to a lesser degree when the United States invaded Iraq.
Figure 8.3. Presidential approval before and after the terrorist attacks of 9/11 and the invasion of Iraq. (Wikimedia Commons)
As discussed in chapter 7, our leaders often exploit this aspect of our evolved psychology, highlighting the potential threat posed by other groups in an effort to turn their followers’ attention away from the group’s internal problems or their own poor leadership. This strategy enhances loyalty and cooperation within the group, thereby strengthening the leader’s position, but these gains come at an ongoing cost of disrupted relationships with other groups (resulting in lost commerce and increased conflict). Thus, our cooperative nature can actually lead to greater conflict between groups, particularly when group leaders value their privileged position in the group more than they value the group’s goals.
Despite the substantial obstacles that these aspects of our evolved psychology pose to intergroup cooperation, even mutually suspicious groups can and do cooperate with each other to achieve overarching goals such as trade and security. Current and historical small-scale societies show numerous instances of intergroup cooperation, often in coalitions against other, more powerful groups, but also in service of intermarriage and trade. As a consequence, intergroup attitudes are most accurately described as an automatic bias in favor of our own group coupled with an ambivalence toward other groups.
This ambivalence manifests itself as a readiness to dislike or like other groups depending on whether they are currently perceived as a threat or an opportunity. The default presence of ambivalence rather than negativity toward other groups is critical, however, as it allows us to notice opportunities when they emerge and form mutually beneficial cooperative ventures across group boundaries. Treaties and alliances are thus most effective when all parties share a common goal so that the intergroup threat is defused and cheating is perceived as impossible or of no potential benefit (more on this point next).
Relativity Disrupts Intergroup Relations
As I discuss in chapter 4, our sense of fairness is driven by the comparison between our outcomes and those of others in our social network. This relativity emerges from the fact that position in the status hierarchy is a critical determinant of one’s attractiveness as a mate. Status differences between groups are also important determinants of individual outcomes. By the time Homo sapiens began colonizing the distant reaches of the globe, we were in frequent conflict with other groups over resources. Indeed, much of human history has been a story of stronger groups pushing weaker groups away from preferred hunting grounds, watering holes, and fishing sites. We marvel at the audacity of our ancestors who struck off into the unknown, but a fair portion of human expansion and exploration reflects desperation rather than bravery. As often as not, exploration meant that our ancestors were escaping, or being forced to abandon preferred areas by their stronger or more aggressive neighbors.
Many scholars hold a romantic view of our past and like to think that human violence is a product of our modern life and of the disconnection and anomie created by urban living. But as Steven Pinker has shown so clearly in The Better Angels of Our Nature, this view is false. If we were so nice to one another prior to the advent of modern living, why do ancient human remains show so many projectile wounds? For that matter, why are injuries to the left side of the body so common? Rocks don’t fall disproportionately on the left side of our heads, or our left arms, or the left half of our rib cages. But weapons wielded by right-handed opponents do, so it’s no wonder many of our ancestors met their demise from wounds to the left side of their bodies.
Evidence for hostility between groups can also be found in the ancient cliff dwellings that dot the American Southwest and various other places around the world. When you visit these sites you wonder why anyone would choose to have babies and raise a family on the side of a cliff when they could have a much less precarious life in the valley below. The answer, of course, is that people chose to live on cliffs in Colorado and New Mexico because the cliffs were safer than the valley below.
Valleys provide little risk of falling, but when their inhabitants are nasty, they can be very dangerous places. Cliff-side living arrangements provide protection against attack, but at an ongoing cost of life and limb, particularly when people accessed their cliff dwellings via rickety ladders at the best of times. These dangerous living arrangements provide evidence of escape-driven expansion and show the cost to one group of people when another group becomes comparatively more powerful. For this reason, relative fairness can matter as much between groups as within them.
Due to the importance of relative fairness, humans have evolved a hypersensitivity to the possibility of being cheated. This sensitivity can be seen in various aspects of human psychology, one of which is an enhanced capacity to solve problems when they are phrased in terms of detecting cheaters compared to when they are phrased in terms of general rules of logic. Consider the following problem adapted from experiments by Leda Cosmides of UC Santa Barbara and her colleagues. In Figure 8.4 a series of cards indicate what people are either eating or drinking for breakfast. One side of the card shows what the person is eating, and the other side shows what he or she is drinking. Your task is to turn over as few cards as possible to test the accuracy of the rule “Everyone who eats cereal also drinks orange juice.”
Figure 8.4. Rule testing: “Everyone who eats cereal also drinks orange juice.”
As you can see, Jordy is eating cereal, and Maya is having pancakes, but we can’t see what they’re drinking. Sam is drinking orange juice, and Sophia is having coffee, but we can’t see what they’re eating. If you wanted to test the rule that everyone who eats cereal also drinks orange juice (by turning over as few cards as possible), whom would you check? Would you look to see what Jordy and/or Maya are drinking? Or might you check what Sam and/or Sophia are eating? According to Cosmides and her colleagues, this should be a relatively difficult problem to solve, as it relies on formal logic. Take a moment to decide for yourself.
Before we discuss the answer to this question, let’s consider an alternative version of the problem that Cosmides also gave her participants. For this alternative problem, your task is to test whether people are breaking the rule “People aren’t allowed to drink cassava juice unless they have a tattoo.”
Here we can see that Jordy is drinking cassava juice, and Maya is having orange juice, but we can’t see whether they have tattoos. Sam has no tattoo, and Sophia has a tattoo, but we can’t see what either of them is drinking. If you wanted to test whether any of them was breaking the rule that you must have a tattoo if you want to drink cassava juice (again, turning over as few cards as possible), whom would you check? According to Cosmides, this should be a comparatively easy problem to answer. Take a moment and see what you think.
Figure 8.5. Rule testing: “People aren’t allowed to drink cassava juice unless they have a tattoo.”
Returning to the first problem, if you’re like most participants in Cosmides’ experiments, you probably checked Jordy to be sure he is drinking orange juice, but you probably failed to check Sophia to make sure she isn’t eating cereal. Given that she’s drinking coffee, if she’s eating cereal, she’s violating the rule that everyone who eats cereal also drinks orange juice. Consequently, checking both these people is critical to detecting if the rule has been violated. It doesn’t matter what Maya is drinking, as no one said people who eat pancakes can’t have orange juice, and it doesn’t matter what Sam is eating—again, for the same reason. Even when people get this problem right, it takes a fair bit of concentration to work out whom to check and who can be ignored.
In contrast, most people find the second problem about cassava juice and tattoos pretty straightforward, because it taps into our evolved propensity to be on the lookout for cheaters. People typically test Jordy to be sure he has a tattoo, and they test Sam to be sure he’s not sneaking cassava juice when he’s not allowed. They don’t bother testing Maya, because the rule isn’t relevant to her, and they don’t care what the tattooed Sophia is drinking because she’s allowed cassava juice if she wants it, but of course is not required to drink it.
The very same problem that people struggle to solve when it’s framed in terms of logical rules suddenly becomes easy to solve when it’s framed in terms of following rules. We aren’t very good at formal logic, but evolution has ensured that we are very good at detecting cheaters. This experiment suggests that we are chronically alert to the possibility of cheating, which enables our cognitive machinery to function more effectively in such contexts. And perhaps most important for intergroup relations, this increased cognitive sensitivity to cheating disappears when people are in situations in which they believe cheating is impossible.
So how do concerns about relative fairness and cheating impact efforts to attain peace and global security? The unfortunate upshot of these concerns is that when groups, societies, or nations attempt to negotiate peace treaties or even trade agreements, they are hamstrung by the desire of both sides to ensure that the other side is not getting a better deal. Because fairness concerns are relative, it is not sufficient for an agreement to benefit both sides compared to the status quo. Rather, agreements must not be seen to benefit one side more than the other. Concerns with relative status ensure that people will reject a treaty, even one that is better than their current arrangement, if it is perceived as bringing greater benefits to the other party.
This concern about relative outcomes is compounded by hypersensitivity to the possibility that the other side might be cheating and not meeting its obligations under the agreement. Because people are so sensitive to cheating, they tend to overreact when they see any hints of it, and quickly stop meeting their own obligations so that they do not provide others with a relative advantage. For example, if two countries agree to a moratorium on nuclear testing, but they suspect each other of cheating, they are both likely to start testing in secret to avoid falling behind in a nuclear arms race. As a result, any system of agreements can rapidly collapse if there is insufficient ability to detect or insufficient authority to punish cheaters.
International rules can be created to punish cheaters, but sovereign nations are typically loath to agree to supranational treaties that include sanctions that could be directed at them. To choose a recent example, China ratified the United Nations Convention on the Law of the Sea in 1996 but refused to accept the 2016 ruling under that law by the international tribunal in The Hague, denying the validity of its claims in the South China Sea. The Chinese Foreign Ministry released a statement noting that the decision “has no binding force.” China is far from unique in this regard, as a similar reluctance has been shown by the U.S. government to allow international bodies to have jurisdiction over its actions. There are exceptions to this rule, as exist in many trade and armaments agreements, but such treaties often follow rather than precede the establishment of trust, or they emerge in domains in which rivals’ interests align.
For these reasons, technical solutions that make cheating impossible can enable agreements to succeed that would otherwise fail through mistrust. For example, countries might easily lie about their nuclear-enrichment activities, leaving other countries to wonder if perhaps they should secretly engage in their own enrichment. In response to this situation, physicists have shown that commercial imaging satellites can detect plutonium production through changes in the atmosphere, thereby providing clear evidence if a country is cheating on its treaty obligations. Such evidence can forestall an arms race that nobody wants but everyone feels compelled to join lest they fall behind.
Humans Evolved to Be Self-Deceptive Hypocrites
Predator-prey interactions must eventually end in death: one becomes dinner or the other starves. In contrast, competition between members of the same species usually involves elaborate signaling that is intended to clarify which individual is stronger before conflict escalates to the point of injury. It is in neither the winning nor the losing party’s interest to fight over resources, as even winners get hurt in fights. Consequently, it is in both parties’ interests to determine who would win if the fight were to take place, with this determination followed immediately by deference or flight by the party destined to lose. Only when competitors appear to be equally matched does a conflict over resources escalate into actual physical combat.
For this reason, competition among members of the same species rarely relies on actual force, as the threat of force is a deterrent to conflict. Human conflicts are guided by the same principles as those of other animals, but the fact that warfare is so common testifies to the frequency with which the two sides are unable to agree on who would win a fight.
Because both parties typically suffer costs when a competition escalates to violence, contests between members of the same species are typically a blend of truth and exaggeration by each party intended to convince the other party to back down. Exaggeration would disappear if there were no cost to testing one’s abilities against those of one’s opponent. If we’re competing over the last slice of cake and I think I might be stronger than you, I’ll just punch you and find out. But there is a notable cost to this test, as you are likely to punch me back—a bummer under the best of circumstances, but particularly so if you’re stronger than I am. It is this guaranteed cost of competition that allows deceptive individuals to exaggerate their strengths and downplay their weaknesses without necessarily getting caught. This type of exaggeration can be seen throughout the animal kingdom, such as when moose or hyenas raise the hackles on their back to appear larger, or when crabs grow unnecessarily large claw shells that they do not fill with muscle.
As we saw in chapter 5, self-deceptive overconfidence is also ubiquitous among humans, who typically believe they are better, stronger, faster, and more attractive than they actually are. This overconfidence plays a critical role in conflict escalation, as it causes the eventual losers of a conflict to believe that they will emerge victorious. For example, both sides in the American Civil War believed they would win in just a few months and with limited casualties. These self-deceptive beliefs led politicians on both sides to orchestrate the deaths of more than six hundred thousand of their fellow Americans. In combination with an evolved lack of cooperativeness with other groups, the belief in one’s own likely victory is a driving force toward conflict.
Self-deception plays an important role in the failure of the losing side to predict its eventual loss, but the advent of nuclear weapons seems to have created a new reality in which people appreciate the deterrence value of such extraordinary force in the absence of using it. The primary advantage of nuclear arms appears to lie in the realization that even the winning side will suffer intolerable losses, and thus both sides can continue to predict their eventual victory but choose not to escalate.
Self-deception helps people believe not only that they are stronger or smarter than they actually are but also that their own actions are more moral than the apparently identical behaviors of others. For example, if I take a second helping of cake and you end up with none, I can assure myself that my apparent selfishness was just an oversight, as I didn’t notice that you hadn’t eaten dessert yet.* If you do the same thing to me, I’ll be appalled at your poor manners and gluttony.
Because I’m inclined to recast my own motives in a positive light, even if you and I go through life engaging in the exact same behaviors, I will regard my actions as more moral than yours. This hypocrisy is fundamental to human nature, and like self-deception more generally, it evolved to help us persuade others that even when our actions aren’t exemplary, our hearts are in the right place. This hypocrisy extends to other members of our group, as we tend to give our own group the benefit of the doubt, but we don’t extend this courtesy to other groups.
And so it is that we trust our own group’s intentions but doubt the intentions of other groups. For example, despite having a large arsenal of nuclear weapons, Americans “know” they would never use them except in self-defense. Indeed, to Americans, it is inherently obvious that their nuclear arsenal was built for deterrence rather than aggression. But Americans do not extend this trust to other countries. To Americans, it is also inherently obvious that Iran has no need for nuclear weapons other than to play a disruptive role in the Middle East. These “facts” are so obvious to Americans that when other countries deny their own aggressive intent, or question American claims, their denial and questioning are perceived as disingenuous and a strategic bargaining stance. Of course, from the perspective of America’s rivals, the story is a mirror image, and such American claims are highly suspect.
In summary, humans evolved to be highly cooperative, but the underlying evolutionary pressure was a fight for survival. Our cooperative nature evolved to make us fiercer competitors. So, it should come as no surprise that our cooperative nature doesn’t extend automatically to members of other groups. Indeed, other groups were often a serious threat to our ancestors’ survival, so cooperation across group boundaries relies on a very tenuous form of trust. Due to the fact that fairness is relative, this trust between groups is threatened whenever we perceive another group as benefiting more from an agreement than we do, even if that agreement is clearly more beneficial than no agreement at all. Lastly, because we hypocritically perceive the motives of our own group positively but the same motives of other groups as suspect, we are unwilling to extend the benefit of the doubt to other groups but are dubious when other groups fail to extend the benefit of the doubt to us.
All these psychological factors pose important obstacles to our ability and willingness to achieve lasting peace and security with members of other ethnic groups, religions, and nations. But our evolved psychology is also highly sensitive to context, as it is the flexibility of human cognition and behavior that has made us such an evolutionary success story. Thus, the barriers to peace imposed by these deeply ingrained psychological tendencies can be overcome, not through reassurance or denial, but through structures, processes, and agreements that align the interests of previously hostile groups or through agreements and verification strategies that bypass these concerns.
When people see their interests aligned with other groups, or when they believe that it is impossible to cheat on an agreement, they are no longer hypervigilant for signs of cheating; nor are they tempted to cheat themselves. It can be difficult to align the interests of different groups, particularly when the groups have a long history of conflict, but numerous societal forces can achieve this goal over time. Increasing democracy, greater awareness and understanding of other cultures through increased contact, and numerous other societal changes drive groups toward cooperation and away from conflict.
The increasing integration of the international community through travel, trade, and tourism (as well as increasing integration over the internet) has the potential to create in many people an overarching group identity as fellow humans, rather than as members of certain tribes, ethnicities, countries, or religions. When such alignment of interests and redrawing of group boundaries are not possible, scientific advances in the capacity to detect cheaters, combined with agreements that are based on a realistic understanding of our evolved psychology, create the circumstances that make it possible to trust by verifying.