Survival of the Friendliest

Why did kindness, not strength or intelligence, make humans the dominant species? In Survival of the Friendliest, Brian Hare and Vanessa Woods challenge a century of belief that evolution rewards aggression and competitive dominance. They argue instead that the true secret of our species’ success lies in an unexpected place—our capacity for friendliness. Not naive sociability, but a deep biological and cognitive adaptation that allowed humans to cooperate, communicate, and build vast social networks capable of innovation, empathy, and progress. This friendliness, they claim, is the key to understanding both the best and worst in human nature.

We usually think of “survival of the fittest” as meaning the strongest triumph while the weak perish. Hare and Woods dismantle this misconception, reminding us that Darwin himself emphasized sympathy and cooperation as essential to evolution: “Those communities which included the greatest number of the most sympathetic members would flourish best.” From mitochondria joining forces to form cells to ants creating superorganisms, friendliness—intentional or incidental cooperation—has always been nature’s magic formula for survival.

The Friendliness Revolution

The authors trace friendliness not as a cultural value but as an evolutionary strategy. They show that cooperative communication—not warfare or dominance—turned Homo sapiens into the planet’s most successful species. By contrast, other humans with equally large brains, like Neanderthals, vanished. Why? Because they lacked the cognitive superpower that comes from friendliness: the ability to coordinate, empathize, and share knowledge across individuals and generations. This shift led to larger groups, better technology, and faster cultural innovation.

The book invites you to rethink human evolution as a story not of conquest but of connection. Hare’s research on dogs reveals how animals that evolve friendliness toward another species (or toward their own) gain powerful new mental capabilities. Dogs didn’t become smarter than wolves—they became more tolerant and better communicators. Bonobos didn’t defeat chimpanzees through violence—they thrived through empathy and female-led cooperation. Humans, Hare argues, are both: self-domesticated apes who traded aggression for connection and reaped enormous cognitive benefits in return.

The Flip Side of Our Friendliness

But there’s a catch. The same biological circuits that make us loving and altruistic toward our group also make us capable of unspeakable cruelty toward outsiders. Hare calls this dual nature “the darkest paradox of friendliness.” When we perceive a threat to our community, our empathy circuits shut down. We no longer recognize others as fully human—a process psychologists now call dehumanization. This mechanism explains genocide, political hatred, and modern polarization. The authors use the U.S. Congress’s transformation—from Reagan’s cross-party socializing to Gingrich’s polarization machine—as a case study of what happens when friendship across groups declines.

The evolutionary lesson is chilling yet hopeful: friendliness built our world, but limiting its scope to “our kind” can destroy it. Hare and Woods’ self-domestication hypothesis isn’t just a creation story—it’s a call to expand our circles of empathy. Understanding that tolerance isn’t weakness but genetic strength could help us short-circuit the tribal instincts that fuel modern hatred.

Why It Matters Today

You live in a world wired for social connection. Technology, politics, and culture all depend on human collaboration. But the same evolutionary mechanism that helped us cooperate also drives prejudice and nationalism. By showing how friendliness evolved through natural selection—and how it transformed our brains, faces, and societies—this book offers not only an explanation of humanity’s success but a roadmap for its survival. The message is simple yet revolutionary: to thrive, we must make friendliness our competitive advantage again.

Friendliness made us human. But only by widening our definition of “us” can we stay human.

Through case studies—from fox farms in Siberia to bonobo sanctuaries in Congo to Washington’s halls of power—Hare and Woods build a persuasive argument: our brains evolved to seek connection, not conquest. The way forward isn’t more dominance or division but rediscovering the evolutionary gift that binds us together: survival of the friendliest.

Imagine breeding animals only by choosing the kindest ones—not the strongest or smartest—and watching their bodies and minds transform. In Siberia, geneticist Dmitry Belyaev did exactly that. Working with silver foxes, he selected only those that tolerated human touch. Over generations, these foxes not only became friendly but developed floppy ears, piebald coats, shorter snouts, smaller teeth, and calmer brains. They were self-tamed by friendliness. This astonishing experiment proved that social selection alone can change physiology, behavior, and even cognition.

Friendliness Changes Everything

Belyaev’s “friendly foxes” did more than wag their tails—they mirrored evolutionary shifts seen across domesticated species. Their stress hormones dropped, serotonin rose, and they developed prolonged playfulness and smoother social interactions. They even responded to human gestures intuitively, much like dogs. When Hare tested them, these foxes understood pointing cues that their aggressive cousins ignored, showing that friendliness itself creates new cognitive flexibility. (Similar studies on dogs and bonobos confirmed these effects.)

An Evolutionary Shortcut

Domestication doesn’t require human control. Hare calls this process self-domestication—a natural selection for tolerance rather than aggression. Wolves that scavenged around human camps, feeding on garbage and feces, didn’t need taming; their calm temperament let them pass along their genes. The friendliest survived, slowly becoming dogs. Likewise, urban coyotes, foxes, and deer adapting to human environments show parallel patterns of friendlier behavior, reduced stress, and altered morphology. The world’s ecosystems are quietly rewarding sociability.

Implications for Human Evolution

The fox experiment illuminated what might have happened in us. If friendliness toward others of our own species could remodel animal brains and bodies, the same dynamic could explain why Homo sapiens evolved differently from other humans. Over time, tolerance reshapes hormones, faces, voices, and social cognition—traits central to forming societies and culture. In Belyaev’s lab, selection for kindness produced more than cute foxes—it produced a biological blueprint for humanity’s success.

Domestication isn’t about captivity—it’s about connection. When aggression loses its advantage, evolution chooses cooperation.

Understanding this process reframes how we see our species’ origin story. We didn’t get here by outmuscling rivals but by learning to get along. The domestication revolution—the victory of friendliness over fear—turned foxes into companions, wolves into dogs, and a band of nervous primates into humans capable of building civilizations.

If chimpanzees are echoes of our violent instincts, bonobos are reminders of what we could be. Brian Hare’s studies at the Lola ya Bonobo sanctuary in Congo revealed that bonobos and chimpanzees are nearly genetically identical—yet their worlds differ dramatically. Bonobos live without alpha males, prefer affection to aggression, and resolve conflict through collaboration and sex. This friendliness isn’t accidental; it’s evolution’s way of keeping peace alive.

How Females Won the Revolution

Bonobo society flipped the evolutionary script. Female alliances, supported by empathy and cooperation, subdued male aggression. They chose calmer mates, protected infants fiercely, and drove violent males from power. The result? A species where no bonobo has ever been observed killing another, and strangers are met with curiosity instead of hostility. They share food even with individuals from other groups—something chimpanzees never do.

Friendliness Alters the Brain

Biologically, bonobos differ from chimpanzees in remarkable ways. They produce less testosterone, more serotonin, and have smaller, more globular faces—signs of self-domestication. Their juveniles maintain playfulness into adulthood, much like the perpetual youth seen in dogs. They even outperform chimps on cooperative tasks, waiting their turn, sharing food, and reading gestures with sensitivity reminiscent of human children.

Lessons for Us

Bonobos teach a simple truth: evolution rewards tolerance. By favoring friendliness and maternal cooperation, they’ve escaped cycles of violence and power struggles that plague both chimps and humans. Their success suggests that empathy and social bonding aren’t luxurious traits—they’re survival tools. Studying bonobos helps us see how our own species might have taken similar steps, evolving from fearful hominins into collaborative communities capable of collective progress.

Bonobos aren’t hippie apes—they’re evolutionary proof that peace works.

When Hare compares bonobos to dogs or experimentally tamed foxes, he finds the same biological signatures—reduced stress hormones, greater serotonin, and creative cooperation. Nature’s recurring message is clear: when friendliness becomes the rule, violence loses its purpose.

Could humans have domesticated themselves? Hare and Woods argue yes—and the evidence lies in our faces, our brains, and our behaviors. Around 80,000 years ago, Homo sapiens underwent natural selection for friendliness within our own species. Those less reactive, more tolerant, and better at communicating cooperatively thrived in larger social networks. This “self-domestication” gave us the cognitive edge to outcompete other humans and create culture as we know it.

The Science of Friendlier Minds

Psychologist Jerome Kagan’s work on emotional reactivity shows that people born less reactive to fear tend to be more socially competent as adults. Hare connects this to domestication: like Belyaev’s foxes, low-reactive humans developed enhanced communication and higher tolerance. Over time, natural selection favored those who could cooperate without threat, linking emotional stability to cognitive sophistication.

Faces of Domestication

Our skulls tell the story. Comparing ancient fossils, Hare’s collaborators found that over tens of thousands of years, human brow ridges receded, faces shortened and narrowed, and brains shrank slightly while becoming more globular—traits seen in domesticated mammals. Elevated serotonin levels likely contributed to this transformation, softening aggression and reshaping bone growth. Even our white sclerae—the whites of our eyes—helped us communicate subtly, allowing for trust through gaze and cooperative emotion reading.

The Human Advantage

Self-domestication didn’t make us physically stronger—it made us socially smarter. Expanded oxytocin and serotonin networks made us more empathetic, while self-control amplified our ability to plan and cooperate. Unlike bonobos, we combined tolerance with deliberate calculation—friendliness became intentional. This fusion of emotion and logic produced a species capable of building civilizations, writing laws, and fostering innovation while maintaining large, peaceful groups.

We didn’t thrive because we got smarter; we thrived because we got friendlier.

Understanding human self-domestication offers a new lens on evolution: our cultural explosion—from cave art to commerce—was born not from competition, but connection. The paradox is that the same friendliness that made us flourish can turn dark when we restrict empathy to “our group.”

Friendliness built civilization, but fear of outsiders still threatens it. Hare’s accounts of genocide—from the Banyamulenge massacre in Congo to modern racial violence—show how human empathy can collapse when group boundaries harden. Neurologically, the same oxytocin that bonds families and communities also fuels defensive aggression when loved ones are threatened. The mother bear instinct lives in us all.

How Dehumanization Works

When you perceive outsiders as dangerous, your brain literally stops recognizing their humanity. Neural scans show reduced activity in the medial prefrontal cortex and temporoparietal junction—regions tied to empathy and moral reasoning. This is what Hare calls “the unplugging of our mental network.” Once empathy turns off, cruelty becomes permissible. From Nazi propaganda to modern polarization, dehumanization operates by suspending compassion for those deemed “other.”

The Universal Mechanism

Across history and cultures, humans have used simianization—comparing rivals to apes—to strip them of humanity. Experiments by psychologist Nour Kteily using the “Ascent of Man” scale prove that people consistently rate opposing groups as less evolved, whether Muslims, Roma, or politicians. This pattern appears everywhere: perception of threat predicts moral disengagement, and reciprocal dehumanization spirals into violence.

The Cost of Losing Connection

When friendliness becomes exclusive—reserved for your own circle—it transforms into hatred. Modern politics, digital tribalism, and xenophobia are all expressions of this ancient glitch. The same circuits that once helped us protect our kin now rationalize cruelty toward strangers. Hare shows that only deliberate social contact—friendship across groups—can reactivate empathy and stop this biological process.

The war within our nature is not between good and evil—but between love and fear.

Recognizing this duality helps us move forward. Understanding dehumanization as an evolved mechanism, not moral failure, offers a path to prevention. The cure is not punishment—it’s reconnection.

Humans evolved to resist tyranny. In the book’s later chapters, Hare and Woods connect evolutionary tolerance to social progress. In small hunter-gatherer bands, group members punished bullies and shared power equally—a natural form of democracy. Agriculture and resource accumulation broke this balance, allowing despots to rise. Modern liberal democracy, they argue, is our species’ most successful attempt to re-create those evolutionary checks on dominance.

Democracy as Self-Domestication

Just as evolution selected for friendly individuals, democracy selects for cooperative institutions. Madison’s Federalist Papers predicted human “mutual animosities” centuries before neuroscience confirmed them. America’s founding design—checks, balances, and representation—mimics evolutionary solutions to prevent group conflict. When friendliness fails, polarization blooms, and democracy falters.

Extremism: The New Aggression

The rise of the alt-right, neo-nationalism, and ideological extremism represents the reemergence of dominance psychology. Studies show that those high in Social Dominance Orientation and Right-Wing Authoritarianism crave hierarchy and sameness, mirroring alpha behavior among aggressive primates. Education alone can’t erase intolerance—only contact and empathy can, as experiments in interracial housing, military cooperation, and friendship networks demonstrate.

Friendship as Political Medicine

Across every chapter, Hare returns to the lesson that friendship fixes broken systems. When Republicans and Democrats stopped socializing across party lines, collaboration collapsed. When soldiers, roommates, or neighbors interact across difference, prejudice falls. Democracy, at its core, is a continuation of our evolutionary legacy—a structured arena for cooperation among outsiders.

Democracy isn’t just a political experiment—it’s a biological inheritance of our friendliness.

If we fail to sustain empathy across divides, democracy could regress into the dominance hierarchies we escaped millennia ago. The antidote isn’t more control—it’s more connection.

The book’s final insight circles back to Hare’s lifelong companion, Oreo the Labrador. Our relationships with animals reveal the deepest truth about ourselves: empathy isn’t limited to human circles. Hare shows that kindness toward animals predicts kindness toward people, while cruelty to animals often precedes cruelty to humans. This shared moral foundation suggests that widening our empathy to include all creatures may safeguard our civilization’s future.

The Animal Test of Humanity

Studies show that people who see animals as vastly different from humans are more likely to dehumanize immigrants and minorities (Hodson & Dhont). The “animal-human divide” mirrors racism and classism—the belief in superior and inferior groups. Societies that cherish dogs, like Aboriginal Martu people who say “dingoes are our mothers,” blur this divide and live more harmoniously across species and cultures.

Dogs as Evolution’s Mirror

Dogs evolved to read our gestures and emotions better than any other species. Our bonds with them reflect our own evolutionary superpower: friendliness. Interestingly, Hare’s experiments link belief in breed hierarchy (dog social dominance orientation) with belief in human hierarchy—those who favor “purebred superiority” also tend to endorse human inequality. The lesson? True friendship rejects hierarchies, even across species.

Friendship as the Measure of Civilization

Claudine André’s bonobo rescue in war-torn Congo embodies this ideal. She teaches children compassion for animals so they’ll be kind to people—a full-circle expression of Hare’s thesis. To love another being, whether animal or human, is the pinnacle of self-domestication. Evolution made us social; morality asks us to extend that gift to all life.

Our survival depends not on fighting harder, but on befriending wider.

The book closes where it began—with Oreo, the dog who taught Hare that genius isn’t dominance or intellect but the ability to connect. Measured by how many friends we make, not enemies we defeat, survival of the friendliest offers a blueprint for a kinder evolution—one that includes every living creature.