Our Tribal Future: How to Channel Our Foundational Human Instincts into a Force for Good

Begin Reading

Table of Contents

About the Author

Copyright Page

Thank you for buying this

St. Martin’s Publishing Group ebook.

To receive special offers, bonus content,

and info on new releases and other great reads,

sign up for our newsletters.

Or visit us online at

us.macmillan.com/newslettersignup

For email updates on the author, click here.

The author and publisher have provided this e-book to you for your personal use only. You may not make this e-book publicly available in any way. Copyright infringement is against the law. If you believe the copy of this e-book you are reading infringes on the author’s copyright, please notify the publisher at: us.macmillanusa.com/piracy.

To my Fireteam—oaths once spoken, remain unbroken.

PROLOGUE

In Whom Do You Put Your Trust?

Without trust … civilization collapses.

—Yuval Noah Harari, 2022

For all social species, one of the most intractable problems is whom to trust. I call this the Trust Paradox. A paradox can be defined as the contemplation of a seemingly self-contradictory statement that can help to illuminate a larger truth. As the philosopher G. K. Chesterton quipped, A paradox is simply Truth standing on its head to get our attention. At first glance, the question In whom do you put your trust? does not seem controversial, never mind paradoxical; the answer is usually agreed upon by scientist and layman alike. You trust family.

Your kin shares your blood. On a foundational level, you and your kin are one and the same. The genomes imprinted in the cells that instruct who and what you are closely resemble those of your immediate family and cousins. Kin selection—the preferential bias for those who are genetically related—was the first answer concocted by evolution several hundred million years ago and has faithfully served Earthlings ever since. The challenge is scale. When considering plants, social insects, and even naked mole rats, kin selection works predictably. However, when you scale up complexity to species that rely on meaty brains, long-term memory, and special kinds of social arrangements, then something else is needed.

The thought experiment of the Trolley Problem is a touchstone example of this challenge. Over the history of philosophy, it has evolved into a number of iterations, but is distilled to something like this: You are riding in a trolley without functioning brakes. On the current track stand five people who are certain to be killed if the trolley continues on its path. You have access to a switch that would divert the trolley to another track, but another individual stands there. That person will be killed if the switch is activated. So do you switch tracks or not?

When we are confronted with this thought experiment, we face an ethical dilemma. That’s because our nervous system, housing our massive brains, has multiple—sometimes competing—internal structures; these brain regions evolved for different functions, and thus compete for neural resources over what is the moral (or ethically optimized) outcome. While the high-minded forebrain seeks idealistic outcomes based on logic, reason, and numerical utilitarianism, the more ancient limbic system seeks to maximize principled* outcomes that preserve harmony for your group, and the most core biological system seeks only outcomes that maximize your own odds of survival.

This is where the Trust Paradox comes to light. How do we solve the problem of whom to trust when different parts of our brain seek different solutions to the same problem? This is a paradox worth investigating, because the fate of our species depends on a scientifically robust solution to the contradictions we inherited.

The Trust Paradox is a challenge faced by all life, but answers to the question have varied depending on evolutionary pressures. Even within an individual species, the answers can change over time as it gains a foothold over its environment. Once our ancestors got the hang of survival and proliferated, their success, paradoxically, came back to haunt them. With so many people living in ever-expanding larger groups, how did we begin to scale trust to individuals who weren’t family? As we will explore in this book, humans innovated novel ways to solve this problem. The next solution, after kin, was friendship. Rare in the animal kingdom, friendships worked keenly for humans living in face-to-face social worlds. Humans are not the only species with friendship, but its not typical in the animal world and the way human friendship is expressed is special. Friendship serves as our species’ crowning ethical achievement and has been suggested to be the origin point for the evolutionary emergence of morality. As opined by Nicholas Christakis: Our assembly into networks of friendships sets the stage for the emergence of moral sentiments. At their core, moral compunctions relate to how people interact with others, especially those who are not kin and for whom the bonds of kinship and the inexorable workings of inclusive fitness are not enough of a guide … friendship lays the foundation for morality.¹ Perhaps the most noble and virtuous quality ever produced by natural selection is the transcendence of kin selection to a truly moral sensibility expressed by way of friendship. After all, friends don’t need to have sex with each other or share in childrearing in order to feel that they have a special relationship.² This too was a novel, innovative answer to the question In whom do you put your trust?

But at this point in the evolutionary story our ancestors were multiplying in droves. Friendship and kin selection gave us the new and unprecedented heroes of the Paleolithic, the avengers of kin and kith. Myths and legends remain of their exploits—a mother laying down her life for her daughter, a blood brother giving his life for a friend. These were all canonized in the stories that our ancestors passed down by word of mouth, which were later written down by scribes. But this success came with another round of costs incurred by increases to scale. We were so successful in reproducing that we became encroached by strangers. Humanity needed a new answer to the trust dilemma.

The answer was to become tribal.

As we explore the natural history of tribalism, we will see that some three hundred thousand years ago humans chanced upon a revolutionary adaptation that led to the encoding of the Tribe Drive in our DNA. This was the evolution of nested groups, each with their own particular symbols—and enshrined shared myths and values—that bound participants together in trusting relationships. All tribes are, in effect, a type of secret society, and the passwords to unlocking full rights and responsibilities of membership reside in the symbols used to verify that one is part of the tribe. Religion is one such signal. The ancient Israelites recorded it in their sacred texts, in Psalms 16:1: Preserve me, O God, for in You I put my trust. The Mesopotamian goat herders of three thousand years ago were putting to scale the tribal solution our African ancestors had innovated three hundred thousand years beforehand. If we all believe in the same tribal God, we can trust each other even though we may have never before met. If your signal is not received as honest, you gain no entrance into the social inner sanctum. But if others recognize your signals as honest, you pass the test and are treated with a positive bias and, buttressed by your shared identity protective cognition, given tribal privileges. Humanity had a new way to promote cooperation … but at a terrible, horrific cost. Once in-groups exist, by definition, so too do out-groups. It was both feature and bug, curse and blessing. This book is an exploration of the natural history of how our species innovated tribalism as a novel answer to the Trust Paradox. I believe a deep, scientifically robust understanding of the contours of this adaptation will be critical to the survival of our species.

IN THE OPENING CHAPTER OF Part I, The Science of Tribalism, we confront one of the greatest mysteries in science: How do we get from a gene to a behavior? To get to the root of this problem, we’ll begin by exploring the ways in which the drive to be tribal—henceforth, the Tribe Drive—significantly (and mostly imperceptibly) influenced my life. But to do this, we’ll have to pose the fundamental question What is a drive? What does it feel like to be influenced by your genes, hormones, brain, or culture? The naked answer is that most of the time it doesn’t feel like anything—the imperceptibility of the drive is one of the keys to its evolutionary success. Importantly, elevating a drive from imperceptibility to perceptibility will allow us to begin gaining control over it, and not be controlled by it.

In chapter two we will look at one of the most important scientific concepts for understanding the modern human condition—evolutionary mismatch. Mismatch is the idea that humans are adapted for how things were, not how they are. The way evolution usually works is that when an environment rapidly changes, an animal must change with it or go extinct; modern humans have found a way around this, in a sense, because our culture shapes our environments to our needs.

Once we have a better understanding of the drives that influence our behavior, and of the problems that a modern, mismatched society cause in detriment to the healthy expression of those behaviors, we will move on to a scientifically robust definition of the tribe concept. In chapter three, by seeking the answers to the question Why are we tribal? we will explore the archaeology of past human societies to uncover the natural history of tribalism in our species, and survey the latest theories as to why evolution favored the tribal organization of societies.

In chapter four, we will intimately engage the new behavioral science of the Tribe Drive. Drawing inspiration from Robert Sapolsky’s book Behave, we investigate the causal levels of tribal in-group us and out-group them behavior. In the quest to be better equipped at predicting our own Tribe Drives, we’ll consider some of the most powerful factors that lead to the ultimate expression of a tribal behavior.

Unexpectedly, standard evolutionary models fail to address one critical aspect of the Trust Paradox—evolution hides the truth from our eyes! In chapter five, we will hear a revolutionary and startling new idea called the Fitness-Beats-Truth (FBT) theorem. The claim is that evolution by natural selection does not favor true perceptions; in reality, it drives them to extinction. If true, this lays waste to common intuitions, since the very language of our perceptions—including shape, hue, brightness, texture, sound, smell, motion, and even space-time—cannot describe objective reality. If this is true, how do we know that our group identities aren’t fundamentally distorting our perception of reality?

In Part II, The Practice of Tribalism, we will embark on a radical journey into the new practice of applied evolutionary anthropology. Standing on the firm scientific foundation that we built in Part I, we will dare to use the science of the Tribe Drive in praxis, to empower us to build thriving friendships, strong pairbonds (romantic relationships), and protective honor groups. We will call these important groups camps, denoting a tight social network of people sharing resources and dwelling in geophysical proximity with shared identity and superordinate goals. Ideally, these camps are embedded in healthy, prosocial communities.

Knowing the natural history of tribalism is one thing, but in the twenty-first century should we still try to build and belong to distinct groups with strong identities? What are the costs and benefits to doing so? In chapter six, we will consider the case for doing just that by looking at the tangible rewards of a life spent in active pursuit of a cultivated social network with a shared identity—an honor or sympathy group.

The next several chapters will lay down a roadmap, a DIY How-To Guide that teaches us how to find the others. We will look at an evolutionary guide to forging a family and crafting a camp. We’ll also take a deep dive into the latest scientific understanding of the Big Five personality traits so that we can understand the underlying factors that determine whether two people become and stay friends and succeed or fail as a team within a community.

But if tribalism can lead to some of the worst of human behaviors, how do we guard against these dangers? In the final chapters, we will wade into the philosophical and ethical implications of the Trust Paradox. We survey how many thinkers in both camps of philosophy and science have been collaborating in transdisciplinary ways to probe one of the greatest ontological* challenges of both fields: If humans are the product of evolution, is morality objective or the subjective by-product of our evolutionary history?

If tribalism is such a powerful force biasing the human mind to prefer one’s own tribe over another, then what does it mean for the future of humanity? I don’t know the answer. But the new science of cognitive immunology may point us in the right direction. The twenty-first century has been waylaid by ideological derangement. Extremist culture warriors dot the landscape in a winner-take-all attack on each of their enemies. Mass shootings (spurred by loneliness and social isolation), terror bombings (spurred by religious tribalism), and hate crimes (spurred by racist tribalism) are endemic; tribalist ideology is at the very center of the modern epidemic of bad ideas. How do we inoculate ourselves against the tribe virus? In the concluding chapters, I will use the new science of cognitive immunology to craft a ready-to-use tribe vaccine that will serve as an immune booster to combat the tribalist ways of thinking that plague our species.

The ultimate goal of this book is to foster personal and collective empowerment. The Tribe Drive, characterized by its own flawless, internal logic—obey tribal consensus of your in-group at the expense of the out-group—took hold because it got our ancestors out of a lot of scrapes. But now, as our species scales in numbers beyond comprehension, its risks are no less than existential. The following pages will help you to learn its language and know its secrets so that when the day comes, you will not fall prey to its curse but instead elevate yourself with its blessings. The fate of our species hangs in the balance.

PART I

THE SCIENCE OF TRIBALISM

1

THE TRIBE DRIVE

What Is Tribalism and Why Does It Matter?

So next time you hear a raving demagogue counseling hatred for other, slightly different groups of humans, for a moment at least see if you can understand his problem: He is heeding an ancient call that—however dangerous, obsolete, and maladaptive it may be today—once benefited our species.

—Carl Sagan and Ann Druyan, 1993

The science is out. Every citizen has an obligation to understand our drives.

—Geoffrey Miller, 2019

Until you make the unconscious conscious, it will direct your life, and you will call it fate.

—Carl Jung, 1951

What do you think of when you hear the word tribalism?

You may have a hunch, but the word is now used in so many varying contexts by media talking heads, podcasters, and everyday people that it has almost lost its meaning. For many, it conjures images of racism and sectarian violence, playing in a constant loop on the twenty-four-hour news cycle. They may see leaders mobilizing their supporters by pitting the differences of one group against another in a zero-sum political game. For others, though, the first thoughts may be of their own group. They may envision community, family, and faith. It may remind them of the bonds of loyalty that bind us all together, or a true friend demonstrating personal sacrifice and benevolence in a way that blood relations would be pressed to match. There is an element of tribalism in all of these things, but let me tell you what I see from my perspective as an evolutionary anthropologist.

I see a band of Paleolithic humans dancing and singing in a ring around a fire. I see a mother nursing her infant and handing it off to another camp member so that she can attend other business. I see a hunter sharing his prize of meat with an infirm grandmother. Juxtaposing these images of altruism, I also see the very first moment where a human murdered another human not of their kind in cold blood. I see a band of men with sharpened wooden spears and flint-knapped handaxes circling the foraging camp of a rival group in the night, waiting to ambush, kill, or abduct any who may wander out alone.

Beyond these visions of our prehistoric past, I see a twenty-first- century single mother, lonely and exhausted from another sleepless night with her newborn; a Wednesday-night bowling team in matching jerseys celebrating after making a tournament-winning strike; a socially isolated teenage boy entering a school with a loaded semiautomatic rifle. I see churchgoers, soccer hooligans, and suicide bombers. I see Donald Trump and the populism that fueled his rise to presidency, and his followers cheering at rallies and storming the U.S. Capitol.

Tribalism is governed by a force so motivationally powerful that it predicts more of your behavior than does your race, class, nationality, or religion. The formal analysis of this incredible phenomenon has only just begun, but the emerging science reveals that these factors are mere subjugates to our primal instinct to be a member of a tribe. This Tribe Drive is an ancient adaptation that has been a prerequisite for survival for 99.9 percent of our species’ evolutionary history. It is a critical piece of cognitive machinery—honed by millions of years of evolution—that gave us the ability to navigate, both cooperatively and competitively, increasingly complex social landscapes. But now that our species spans billions across the globe, does this adaptation continue to serve us, or is it mismatched to its environment? In other words, what happens when humans become either tribeless or destructively consumed by tribalism?

The Tribe Drive is coalitionary instinct. Specifically, it is the instinct to belong to a nested group—a tribe—that uses symbols that represent a shared reality to identify membership. For good or ill, we all have it. This instinct ignores your political affiliation and cares little for the color of your skin or the gender you identify with. It stays with you from the time you are born to the time that you die. It disregards whether you are rich or poor. It scoffs at your intelligence—and may even use your formal education against you, allowing you to craft more convincing narratives to justify your actions. Surprisingly, neither expertise, intelligence, numeracy, nor political ideology serve as an inoculation to being tribal.¹ Studies show that people with specialized training become better at deceiving themselves and others when truth conflicts with their prior beliefs. In other words, the Tribe Drive is indiscriminate.

Tribalism is the worst kind of manifestation from the Tribe Drive. It is the belief that different identity-based coalitions possess distinct characteristics, abilities, or qualities, especially so as to distinguish them as inferior or superior to one another. Sound familiar? It should. If racism is the belief that skin color can distigiush people as superior or inferior, then tribalism—using skin color as a predictive factor in group identity—is the root code of this phenomenon. This is profound because if we want to solve racism, we have to understand tribalism. You and every person you interact with emit and receive signals embedded with coalitionary information that shape our behavior, and this behavior spills into our social networks and societies. On a daily basis, I take note and register tribalism’s influence on myself and others. This book is about why this matters and why it should matter to you.

In the coming chapters, we will explore the science of how various human drives manifest in distinct behaviors. We will also investigate the anthropological definition of a tribe, and how belonging to one is not always a matter of personal choice. Nor is it only the purview of a handful of people, to be determined by legislators and judicial systems or social justice advocates. Belonging to a tribe is, in fact, the birthright of every human being. One of the most pressing challenges to becoming masters of our drives—not mastered by them—is knowing they exist in the first place. In this chapter, we will uncover the nature of the imperceptibility of the dispositions that influence our behavior. Ultimately, this knowledge will be essential in improving our moral landscapes.

Deconstructing My Tribalism

Looking back now, over the span of my lifetime, the Tribe Drive has been the unseen force lurking in the shadows of not only my origin story, but also some of its most critical, identity-shaping moments. Now I see these moments in a new light; they carry with them through time important lessons, harbored in secret for years until I learned the code to unlock their deeper meanings.

My Conception

My French-Canadian grandfather, Roland Samson, was born in 1928. My Catholic great-grandparents—Emilio and Laura Samson—had twelve children in all, and Roland was the eighth. In 1979, my mother, Dana Monroe, fell in love with my father, Daniel Samson, son of Roland, in part because they were both attending the same religious college. Religious devotion is a theme in the Samson family tree. In fact, my great-grandfather Emilio’s faith at the time forbade the use of contraceptives, which explains in part why they had twelve children, a number unheard of nowadays. My father, in seeking a partner, was hoping to marry one who shared his devotion and religious affiliation. Group affiliation—in this case, religion—brought me into the world as a Samson.

Lesson: Group affiliation guides and drives reproduction.

My First Memory

I watch with some measure of awe as my father stands upon the dais and speaks to hundreds of his parishioners. He leans on a podium embossed with a golden icon of a lion, a boy, and a lamb, symbolizing the millennial age and the coming of Christ. The parishioners look up to him and listen in rapt attention. Moreover, this is an international affair. We are in Martinique, a Caribbean island that’s part of the Lesser Antilles, for a church feast. Even as a young boy, I am struck by the human diversity of the crowd. As with all good shamans, my father nourishes the souls of those in attendance with homiletical concepts of group unity under one ultimate God. The final goal (highlighted from sermon to sermon) is that of worldwide peace when evil will be destroyed, and the lamb (Christ) will come back to rule, paradoxically, with a rod of iron as all nations submit to his will.

Lesson: Religion is a powerful group adhesive and tribal signal.

My First Fight

My family is transferred by the church from New Brunswick, Canada, a primarily English-speaking province, to French Québec. There, as a newly minted fourth grader in a Quebecois French–dominant elementary school, I am standing in defiance of an older, stronger fifth-grade bully. Being one of the only English-speaking kids at my school, my poor French language skills make me an easy target on the playground. I am being goaded into a fight. I have yet to back down, but I don’t dare throw a punch. Are you a pussy, you little English piece of shit!? He launches a punch and I take it in the stomach, doubling over. His friends laugh as he continues to throw blows on my hunched-over body.

Lesson: Language is a powerful coalitional identifier.

My First Friendships

I am kneeling in the dusty basement of my best friend’s home. Metallica’s heavy metal ballad Nothing Else Matters plays in the background. A stainless steel sword tip touches my left shoulder, then my right, and then after an ascending arc, comes to rest on a lock of unkempt teenage hair. Arise, Sir Davers, a [redacted] of the order of [redacted]. We share a sacred, secret handshake known only to our group. The ritual complete, I stand and am embraced by my fictive kin—family by choice, not genealogy. I feel a love and acceptance identical to familial bonds. These first true, time- and stress-tested friends remain by my side and to this day call me Davers. Our secret society, I would learn only as an anthropologist much later, is called a sodality and serves a critical survival function on the band level of tribes.

Lesson: Ritual, symbols, music, codes, and nicknames sum up to make a group’s creed. This creed functions as a proof of group membership.

My Early Awakening

I am twelve years old. My father leaves a book on my nightstand: Carl Sagan and Ann Druyan’s Shadows of Forgotten Ancestors. After several days of it collecting dust, I take it with me to school and begin reading the thrilling saga that starts with the origin of the Earth and ends with the evolution of our species. Little do I know that this book is destined to alter the course of both my life and my father’s. For my father, the book served as the catalyst to the ontologically shocking realization that his fundamentalist church was in error in denying the fact of evolution. Despite the trepidation that came with having to retrain for another career in order to support our family, this would lead to his decision in 1999 to resign his ministry.

Lesson: Even the strongest of tribal allegiances, grounded in the most profound sense of fundamentalist faith, are not immutable. If we no longer identify with a creed, we can relinquish its identity and find a new one.

My First Love

Tears well up in my eyes as the first woman I ever loved tells me: David, it can’t work. We can’t be together. You believe in evolution. I don’t. Our children would be confused. We can’t live a life together… After the encounter, I am driving home in the darkness of Indiana on a backwoods road. It is raining hard, making it difficult to see. The weeping becomes so uncontrollable that I have to pull over for fear of veering off into a ditch. I spend the night alone in the car awash in the anguish of loss.

Lesson: Your ideological belief system, a cornerstone of tribal identity, will influence whom you will love.

My First Win

It is the Southern Indiana football sectional championship, and we are playing on our home turf—Lidey Field at Castle High School in Newburgh, Indiana. I am the starting defensive end for the Knights; the jersey I am wearing features a proud blue-and-gold motif. There are only a few seconds left on the clock and we are up by three points. It is fourth down, and only several yards to the end zone. Harrison High School’s dangerous and agile quarterback snaps the ball; I speed off the line of scrimmage far to the outside of the offensive tackle I had been fighting all game, and as he overcompensates his speed to catch up, I throw an uppercut move to his torso that uses his own momentum against him, sending him crashing to the ground. It is just me and the elusive quarterback now, and every sense in my body is tingling. I am completely focused on him. I send him crashing to the ground with the game- winning sack. I am lifted up by my teammates, and ten thousand screaming fans in attendance share in the sense of victory and conquest that we, "the us-es, are having at the expense of the thems," our fallen enemy. Until that moment in life, I had never felt such glory, never felt such power or sense of purpose.

Lesson: Enacting socially sanctioned physical violence on behalf of one group over another can be intoxicating, thereby reinforcing an addictive quality to the behavior.

My First Political Debate with a Friend

I am shocked! One of my closest, most cherished friends is attacking me with conservative talking points about fiscal responsibility and barbs against the welfare state. I am in a debate with someone whom I love like a brother and whose intellect I respect, yet I feel—to the very core of my being—that he couldn’t possibly be more wrong. I think to myself: How can someone so smart be on the wrong side of history? Being an anthropology graduate student, I have, up to this point, been baptized as a hardcore card-carrying liberal, and I viciously, with no small measure of righteousness, counter with my side’s political talking points. He looks disgusted, an expression I had never witnessed coming from him before. For the first time in my life, I feel a fracture in a cherished relationship and leave the debate angry and confused.

Lesson: If identity is in question, group ideology has the power to fracture historically strong relationships.

My First Hobby

I am on a field of battle, with a thousand other warriors dressed in full plate and leather armor, in Slippery Rock, Pennsylvania. Every year a crowd of twenty thousand congregate for two weeks in what is the equivalent to the Burning Man of medieval martial arts, called Pennsic.* Savage blows rain down on me. I am in the midst of an assault the likes of which I have never experienced. Sweat and dust sting my eyes. I am now exhausted and my shield arm begins faltering inch by inch with the constant drum of rattan swords and polearms beating across my upturned shield. An enemy column plunges deep within our ranks, revealing an open flank. My blood brother† is at my right; he pushes into my exposed left flank, his shield replacing mine. He absorbs the brunt of a charge from two huge adversaries in full plate armor who tower above us and who wish us a violent end. At this point, the enemy push has forced me down onto one knee. With a rage ranging from frenzied to berserk, my blood brother reveals his flank vulnerably and expels both enemy combatants with killing blows. I promise myself never to forget this moment, when a friend puts his well-being and chance of real bodily harm on the line for my sake.

Lesson: Modern humans will spend incredible sums of resources, including risk of bodily harm, to simulate in-group cooperation and competition with out-groups.

My First Year of Field Work

I am in Uganda, Africa. I have been in the field for months now, observing, following, and studying a community of wild chimpanzees. I have followed them to the periphery of their common home range, and I can sense the group of males I am following and observing closely is agitated and anxious. The hair on the alpha male’s body stands erect—a phenomenon primatologists call piloerection—as a pant hoot oooowwaa waaaaaaaai waaaaaaaaai from a rival community echoes across the no man’s land between the two different, warring communities. The males closer to me pant hoot, fear defecate, and run back to the safety of their inner community home range.

Lesson: Ways of delineating us and them are ancient and predate the existence of our species.

My First Depression

In the fall of 2016 I have it all—professional, financial, romantic, and scientific success—yet I am more miserable than I have ever been. Through hard work, grit, and a fair amount of luck, I find myself in a prestigious postdoctoral fellowship that quickly morphs into a multiyear senior research scientist position at Duke University. I work in the lab of Charles Nunn, one of the brightest and most prolific minds in evolutionary anthropology. The work is intellectually challenging and deeply satisfying. We publish innovative, theoretically relevant work at a fantastic rate in respected journals. Durham, North Carolina, equidistant from the coastal beaches and Appalachian Mountains, is a beautiful and charming place to live. Moreover, for the first time in my life, I have financial stability. Despite all this, and having never been prone to bouts of melancholy, I am teetering on the edge of depression. It has been three years since I left Indiana for the pursuit of my career in academia. I left my best friends and my family and now I find myself tribeless and profoundly alone.

Lesson: Being too far removed from our kith and kin increases our vulnerability to a host of mental and physical ailments despite having all other extrinsic needs met.

My First Days Living with African Hunter-Gatherers

I speak with a Hadza elder. The Hadza are a group of indigenous people who have lived here, in north-central Tanzania within the central Rift Valley, for thousands of years. It has been days since I explained in broken field-Swahili the purpose of my research and the camp agreed to collaborate with me. This moment feels significant though, as it is the first time I am alone with the elder. He asks me why I am here. I tell him, Because there are important lessons that your people can teach me and us Westerners about how to live better lives. He nods, and ponders my request. He responds: We live together and depend on each other to survive. It is not always easy, and things between people can become heated, but we know we can rely on each other to survive.

Lesson: In environments analogous to the kinds our ancestors survived in, hunter-gatherers’ only insurance policy against an ever-changing environment is each other.

My Exposure to the Power of Belonging

It is my first year of university. In the hopes of expanding our social network in this new place, my long-standing high school friend and I have pledged one of the local fraternities. As part of the pledging process, we have been working overtime for the fraternity for weeks. Another friend, an African American I befriended in my dorm, recounts to me a recent experience where he was trying to go to a party at this fraternity and they denied his entrance with a Your kind aren’t welcome here denial of entry. When I hear about this, I confront the president of the frat and end up quitting after being dismissed with no meaningful response to the incident. When I compel my friend to leave with me, he, too, dismisses it. This is shocking to me on several fronts, but the one point that has always stuck with me is my high school friend was himself a minority. How could he want to stay?

Lesson: The drive to belong to a group can overshadow our personal identities. Ultimately, we are not born racist, but we are born coalitionist.

My Realization of Ignorance

It is the night of the 2016 U.S. presidential election and Donald Trump is winning. I am stunned, as I am realizing, along with a clearly shaken media, that their prognostications of imminent Democratic victory were to be unrealized. The next morning I wake up to find the final results. My mind reels as I contemplate the alternate reality I now live in. My previous certainty and hubris of what I thought I knew about the world crumbles before me. I feel utterly humbled. My models of reality are inaccurate and corrupt, I think to myself. I know in that moment there are forces in the world I do not yet comprehend and they have the power to affect nations.

Lesson: Entire societies can be driven by the power of tribalism.

WHETHER WE KNOW IT OR not, the Tribe Drive is part of us. In fact, its imperceptibility is part of its power, and it works best when you remain blissfully ignorant of its existence. In the next section, our aim is to derive a deeper understanding of one of science’s greatest investigations: How do we get from something like life’s blueprint—the ATCG(U) nucleotides that make up DNA and RNA—all the way to a behavior?

Reverse Engineering the Drive

The brain is the final conduit, the ultimate pathway, that mediates behavior. And yes, different scientific disciplines will attempt to explain the ever-elusive why behind behavior with their pet "because." Because of childhood experience; because of this or that hormone; because of some cue in their immediate environment; because of diet during gestation; because they had a bad night’s sleep; because of the culture they were born into; (here is an infamous one) because of their genetics. These are all drives. The result of a drive is a disposition that is realized in the process of certain behaviors. Evolution crafts, for every species, the suite of drives that parameterize the dispositions that give life to our behaviors. If the set of drives is successful, it is passed along and the species thrives. If a set of drives fails, the species may dwindle and go extinct. Fascinatingly, every specialist exploring any aspect of the way drives influence behavior is, more often than not, only a bit right; these drives are all intimately, exquisitely intertwined, and they all contribute to the final thoughts, feelings, and perceptions that ultimately produce the behavior.

The topic of drives carries a few burdens, several of which are stained with ideological dye. Let’s cover them up front so that we can move forward more productively. The first is the common consternation of people who are troubled by any link between genes and behavior. Specifically, the claim that individuals with gene x deterministically exhibit behavior y. Much of this concern is justified, as many discoveries produced by a plethora of scientific fields have been maliciously distorted, and pseudoscientific jargon has been used to justify atrocious ends; think here of all the bad isms (e.g., racism, sexism, and many more) that have plagued our species. On the opposite side of the spectrum, with exponential computational powers decoding genomic sequences of countless species with ease, splicing genes therapeutically, and outright editing the blueprint of life, we are living in a golden age of molecular discovery. This leads reductionists to lean heavily on genes as the irreducible part to a complex whole that carries ultimate predictive power.

Robert Sapolsky, a professor of neurology at Stanford University, notes the tension between these two extremes of reductionism and antireductionism.² On the one side, such pseudoscience has fostered racism and sexism, birthed eugenics and forced sterilizations, allowed scientifically meaningless versions of words like ‘innate’ to justify the neglect of have-nots. And monstrous distortions of genetics have fueled those who lynch, ethnically cleanse, or march children into gas chambers. And on the other side, overenthusiasm for genes can reflect a sense that people possess an immutable, distinctive essence … people see essentialism embedded in bloodlines—i.e., genes. As with most extremes, it is best to hedge bets in the middle.

A gene can drive a behavior and at the same time rarely, if ever, determine it. This fact is profound and it devastates a belief in genetic determinism. Making the claim that genes decide is like saying that a dinner recipe decides when to cook a meal. It’s not genes but the environment that decides the when. Importantly, genes aren’t about inevitability. Instead, they’re about context-dependent tendencies, propensities, potential, and vulnerabilities. All embedded in the fabric of the other factors, biological and otherwise.³ Perhaps we can distill all these context-dependent factors down to a single concept—dispositions. An immediate environment triggers a vast network of (often competing and mostly unconscious) dispositions.

Relatively small changes to your genetic makeup can combine to create radical types of beings, including new species—yet rarely forecast behavior. Richard Wrangham, professor of evolutionary anthropology at Harvard University, writes: Mostly, individual gene differences are only weakly predictive.… Genes can influence behavior; they rarely determine it.⁴ The natural world gives us hints when we attempt to figure out the extent to which genes have the power to influence or alter our behavior.

Generally, genes prime traits to be expressed in certain contexts, but a good clue that genes are responsible for a human trait is when the trait is found in most cultures. Anthropologists call these cultural universals. Take, for example, a trait we will revisit often in this book—the disposition for hunter-gatherer societies to exhibit egalitarian social norms. Roughly speaking, foragers live in societies with mild hierarchies and context-dependent distribution of social powers between genders. On the topic, anthropologist Christopher Boehm writes: The egalitarian syndrome … whenever we find a behavior that is universal among the fifty foraging societies … we can appropriately ask if it is likely to have some substantial (if less than wholly ‘determinative’) genetic preparation.⁵ Genetic preparation is a keen way of describing a context-sensitive system that improves the chances of a species surviving a constantly changing environment.

Scientific reductionism (the attempt to explain a phenomenon by reducing it to smaller parts) is the running foil for thinkers who wish to insulate human free will from determinism. In the context of our discussion on drives, take one common anti-reductionist counter: If evolutionists say aggression is adaptive, then logically war is an inevitability. Yet, this simplification overlooks the context sensitivity of the evolved system. Violent behaviors are not unstoppable dictates from tyrannical genes. Behaviors, both good and bad, respond to circumstances: Genes affect the size and sensitivity of different brain regions, the nature and activity of the physiological stress systems, the production and fate of neurotransmitters, and on and on.… A primate that invariably produced aggression as predictably as it went to sleep or felt hungry or pulled away from a smelly cadaver would quickly fail in the evolutionary game. The secret to successful aggression is appropriate behavioral flexibility.⁶ In other words, context is king. For example, two people are in a fistfight. Objectively, both are engaged in violence. One is the aggressor and the other the defender. We often label the former a jerk and the latter a hero. One behavior is good and the other bad, despite both people lighting up identical brain regions and activating their muscles to produce nearly identical behaviors.

On the Imperceptibility of Drives

Another difficulty that clouds the discussion of drives is that, for the most part, only a sliver of them are registered consciously as forces that cultivate our (enacted or suppressed) behavior.* Steven Pinker, professor of psychology at Harvard University, writes in his book The Language Instinct: Our flexible intelligence comes from the interplay of many competing instincts. Indeed, the instinctive nature of human thought is just what makes it so hard for us to see that it is an instinct.… The effortlessness [with which we behave], the transparency, the automaticity are illusions, masking a system of great richness and beauty. Here is the challenge: since we don’t often feel like we are driven by a disposition, it is that much easier to say we know we are not driven. Yet, neuroscientist David Eagleman states: "To know oneself may require a change of the definition ‘to know.’ Knowing yourself now requires the understanding that the conscious you [emphasis his] occupies only a small room in the mansion of the brain, and that it has little control over the reality constructed for you."⁷ To make matters more difficult, we do not even have the capacity to feel a gene in action. We didn’t even know they existed until a nineteenth-century monk, Gregor Mendel, meticulously recorded the results of his experiments on the inheritance of breed traits in pea plants. Donald Hoffman, a professor at the University of California, observes: For the most part, these machinations of genes fly under the radar of conscious experience and foster, but do not force, a choice of action.⁸ If genes don’t determine behavior, can anything? What chance is there, then, that any other single drive determines any behavior? Likely zero. At any given instant, there are many (often competing) drives that ultimately influence the behavior.*

It is important to observe that many of these drives only work effectively as a consequence of being unconscious. Consider the suite of dispositions we call love and its role in finding and keeping a mate. UMass Boston professor Patrick Clarkin writes: Love would not be very good at its job if it was left to rational choice, or if we knew where the off switch was. Instead, it is much more effective because it seems to grab us by the throat.⁹ Critically, the property of a drive being unconscious is often a crucial component of its function. In fact, there is growing evidence that evolution purposefully crafted our (and every other organism’s) perception system to hide reality from us, so that mercifully we would only have to focus on fitness-relevant stimuli; in other words, it protected us from a deluge of incoming data that would distract us from our prime directive—to survive and reproduce.¹⁰

Some readers may cringe at the thought that the only purpose of humanity is to live long enough to make copies of and spread our genes. To this point, Carl Sagan, former planetary scientist at Cornell University, and award-winning science writer Ann Druyan state: "Passion for life and sex are built into us, hardwired, pre-programmed.… So we