The Secret of Our Success
How Culture Is Driving Human Evolution and More
By Joseph Henrich
Category: Psychology | Reading Duration: 24 min | Rating: 4.2/5 (28 ratings)
About the Book
The Secret of Our Success (2015) explores why humans dominate Earth despite being individually weaker and less capable than many other species. It argues that our success stems from cumulative cultural evolution – the ability to learn from others and build on knowledge accumulated across generations. It reveals how this process has shaped not just our societies but our very biology, from our oversized brains to our shrunken guts.
Who Should Read This?
- Thinkers questioning what separates humans from other species
- Students of human evolution and origins
- Parents seeking to understand the nature of childhood
What’s in it for me? Find out why humans succeed through culture, not individual intelligence.
Picture yourself stranded in an unfamiliar forest with a group of colleagues. Your survival depends on finding food, creating shelter, and avoiding danger. Sounds manageable with human ingenuity, right? Now add a twist: you’re competing against a troop of capuchin monkeys who’ve never seen this place either.
Both groups arrive with nothing – no tools, no supplies. After two years, whoever has more survivors wins. Most people would bet on the monkeys. And they’d be right. You probably can’t identify edible plants from poisonous ones. You don’t know which materials make good shelter or how to create fire from scratch.
Your gut can’t process most raw plants that other animals eat easily. Despite having a much larger brain than those monkeys, you’d likely starve while they figured things out. This reveals an uncomfortable truth. Our species spread to every corner of Earth – frozen tundra, scorching deserts, dense rainforests – long before we developed farming or cities. Yet we’re physically weak, slow, and poorly equipped for survival. So what explains our success?
The answer isn't individual brilliance. Humans thrive because we learn from each other and build on what previous generations discovered. Over at least a million years, this process has created a unique feedback loop where cultural knowledge has shaped our genetic evolution, which in turn has enhanced our ability to absorb more cultural knowledge. This partnership between culture and genes has transformed us into something entirely new. In this Blink, you'll find out how this process works, and why it’s fundamentally reshaped both our bodies and our minds.
Chapter 1: Survival depends on inherited knowledge not raw intelligence
Ask most scientists why humans dominate the planet and you'll hear three answers. We’re smarter. We evolved specialized mental abilities for hunting and tracking. We cooperate better than other species.
Each sounds plausible – until you examine the evidence. Researchers tested young children against chimpanzees and orangutans on tasks measuring spatial thinking, numerical understanding, and causal reasoning. The children, despite much larger brains, performed no better. When it came to using objects as tools, chimps scored 74 percent correct while the kids managed only 23 percent. Children excelled in just one area: absorbing information from other people. What about grown-ups?
Japanese scientists pitted university students against young chimps in memory challenges where numbers briefly appeared on screens before vanishing. A chimp named Ayumu outperformed every human when the display time shortened. In strategy games requiring unpredictable choices, chimps consistently reached mathematically optimal play while humans made systematic errors. Real-world tests tell an even starker story. In 1845, a British expedition sailed into the Arctic with reinforced ships, steam engines, and provisions for five years. After ice trapped their vessels, 105 men died on King William Island, despite having spent years in the region.
The local Inuit population lived comfortably on that same island, dwelling in structures built from snow, catching seals through ice holes, and hunting caribou with bows they crafted from driftwood. The men in the expedition never learned these techniques. And they weren’t alone in their ignorance. In 1860, two explorers perished beside an Australian waterway despite eating several pounds daily of cakes they’d learned to prepare by watching local women. They’d missed steps in the processing method. The improperly prepared seeds drained their bodies of essential vitamins, causing them to waste away even as their stomachs stayed full.
Sometimes, though, outsiders do survive. One leader of an Arctic expedition befriended the Inuit, studied their methods intensively, and returned home with most of his crew intact. And Norwegian explorer Roald Amundsen spent multiple winters mastering Inuit techniques before applying them to reach the South Pole ahead of his competitors. The difference isn’t raw intelligence, specialized mental abilities, or teamwork. Survival requires accessing a vast store of knowledge accumulated across many generations. Catching seals demands locating breathing holes in ice, testing them with carved implements, and deploying harpoons with removable tips attached by woven cord.
You need to identify which frozen seawater has lost enough salt for drinking, extract oil from animal fat for lamps, and find specific mosses that serve as wicks. Each skill connects to dozens of others in an intricate web that no individual could recreate alone. So the real secret to human dominance? It’s learning what others know and inheriting wisdom built up over time.
Chapter 2: Collective brains accumulate knowledge across generations
The way we learn from others has been shaped by natural selection. Humans have evolved specialized psychological abilities for absorbing information from people around them. These abilities emerge early and operate automatically. Watch a one-year-old encounter something unfamiliar.
The baby looks at nearby adults, checking their emotional reactions. If the adult shows fear, the infant backs away. If the adult smiles, the baby investigates. This social referencing gets deployed selectively. Infants check others' reactions four times more often when facing ambiguous situations. Under uncertainty, they rely on cultural learning.
By age three, children track who knows things and use that information to target future learning. They preferentially copy models who demonstrate competence, success, and prestige. They also favor older individuals and those who match them on sex and ethnicity. These aren’t conscious choices. The learning happens automatically, outside awareness. Adults follow identical patterns.
In one study, MBA students played investment games with real money that affected their grades. They ended up copying the allocation choices of top performers from previous rounds. This mimicry helped the group find optimal strategies faster than individuals working alone. The greater the problem’s difficulty or uncertainty, the more people leaned on copying others rather than personal experience. These learning abilities create “collective brains”. When individuals learn from each other with enough accuracy, groups accumulate knowledge exceeding what any single person could discover.
The power of these collective brains depends on population size and social interconnectedness. Imagine two populations: Geniuses and Butterflies. Individual Geniuses devise innovations 100 times faster than individual Butterflies. But Geniuses have only one friend to learn from while Butterflies have ten friends each. When an individual does innovate, social connectivity ensures rapid spread: nearly 100 percent of Butterflies eventually acquire innovations while under 20 percent of Geniuses do. Being social beats being smart.
Population size matters because more minds generate more lucky errors, novel combinations, and useful insights. If it takes a group of ten people 100 generations to stumble upon a particular invention, a group of 1,000 people will need fewer than two generations to make the same discovery. Interconnectedness matters because innovations must spread to benefit everyone. Real-world evidence confirms this. In the 1820s, an epidemic killed many of the most knowledgeable Polar Inuit. The population lost the ability to make kayaks, bows, and proper snow house tunnels.
They couldn’t recreate these technologies even when facing starvation. When other Inuit reconnected with them decades later, they immediately relearned everything. Tasmania shows the same pattern. When rising seas isolated it from Australia 12,000 years ago, the population began losing complex tools. Bone tools vanished. Fishing techniques disappeared.
By the time of European contact, Tasmanians possessed the simplest toolkit ever recorded. So, larger, more connected populations develop sophisticated tools and knowledge. Smaller, isolated groups lose them. Our success stems from social networks accumulating solutions across generations.
Chapter 3: Culture physically reshaped our bodies and minds
Humans seem poorly designed for survival. We have mouths the equivalent size of a squirrel monkey’s. Our stomachs hold only a third of the surface area expected for primates our size. Similarly, our colons are 60 percent shorter than expected.
Our teeth are tiny, our jaws weak, and we’re terrible at detoxifying wild plants. Why? The answer is that our cultural techniques replaced our biological functions. Cooking does much of our digestion before food enters our mouths. Heat breaks down plant fibers and meat proteins. Pounding with stone tools tenderizes by crushing muscle tissue.
Marinades chemically break down foods. Leaching removes toxins from poisonous plants. These techniques freed natural selection to shrink our expensive gut tissue and redirect that saved energy toward building bigger brains. And the methods are far from instinctive. Try creating flames without modern tools and you’ll likely fail unless someone taught you. Some foraging populations lost the ability entirely and had to borrow fire from neighbors.
Yet we depend utterly on cooked food. People eating only raw diets struggle to survive even with supermarket access and blenders. Women on raw food diets often stop menstruating. We were also reshaped by our tools. As cultural evolution produced better weapons and cutting implements, natural selection traded our strength for fat and dexterity. Fat stores energy to sustain our huge brains through scarcity.
Our hands gained precision grip and wider fingertips for manipulating complex tools. These anatomical changes came at a cost: extended childhoods. Hunter-gatherer boys don’t produce enough calories to feed themselves until age 18 and don’t peak as hunters until their late thirties. Success depends more on learned skills than physical ability. Chimpanzees become self-sufficient at age five, whereas our brains remain remarkably plastic into our twenties, constantly wiring up new connections as we learn. Cultural evolution also domesticated us socially.
When three-year-olds watch adults perform tasks with unfamiliar objects, they spontaneously infer rules about proper behavior. When a puppet violates these inferred rules, children get angry and protest. Nobody taught them explicit rules, yet they assume the social world operates by norms. We internalize these norms as preferences, making proper behavior feel automatic rather than calculated.
Our brains reward us for following community standards and punishing violators. This norm psychology has allowed humans to live in larger groups governed by shared expectations, which has further expanded our collective brains and accelerated cultural evolution. Accumulated cultural knowledge hasn’t just made survival easier. It’s fundamentally rebuilt our bodies and rewired our minds.
Chapter 4: Evolution favored copying what worked over understanding why
When generations of people learn selectively from successful individuals, populations develop solutions that surpass individual intelligence. This cultural evolutionary process builds adaptations across three major domains: subsistence techniques, social organization, and even genetic traits. Food processing exemplifies technical complexity. Amazonian populations prepare manioc through elaborate steps spanning multiple days.
Without this process, the roots release hydrogen cyanide causing paralysis and death. The original technique accumulated gradually as successful practitioners were preferentially copied, generation after generation. Nobody designed the process or understood the chemistry. Yet when Europeans transplanted manioc to Africa, most populations couldn’t recreate effective methods, despite centuries of trying. As a result, many people have low levels of cyanide in their blood and urine. Social organization reveals even more complexity.
Marriage doesn’t simply express pair-bonding instincts. Community enforcement of fidelity norms increases men’s confidence in paternity, encouraging investment in children. Naming practices create bonds between paternal grandparents and newborns, compensating for lower certainty on the father’s side. These seemingly arbitrary customs generate measurable effects: among foraging populations, marriage creates in-law relationships that are stronger predictors of cooperative behavior than genetic relatedness. Rituals employing synchronized dancing and singing strengthen bonds between participants through mechanisms people can’t articulate. Elders observe that ceremonies impart courage and wisdom without understanding how.
Cultural evolution even drives genetic change. When farming reached northern Europe, populations lost access to vitamin D-rich marine foods. Selection then favored genes reducing skin pigmentation. One variant that lightened skin also disrupted melanin production in irises, creating blue eyes as an unintended consequence. These adaptations work so well because they accumulate successful modifications while filtering out failures across many lifetimes. The process exploits information unavailable to individuals.
Imagine a woman who simplifies her manioc processing based on her own analysis. Removing seemingly unnecessary steps would save daily hours. Her family would suffer symptoms only years later, making the connection nearly impossible for her to detect. Evolution has favored psychology that places faith in inherited practices over personal reasoning. We’ve survived not by understanding everything but by faithfully copying what worked for our predecessors.
Chapter 5: We evolved for a world made of culture
When did our ancestors cross into cumulative cultural evolution? The answer is gradually, over millions of years, with many false starts. Around four million years ago, Australopiths walked upright on two legs with brains slightly larger than chimpanzees. By 3.
4 million years ago, someone used stones to butcher animals and crack bones for marrow. Fossil hand bones from 3. 2 million years ago show anatomical changes – lengthened thumbs, widened fingertips, strengthened precision grips – suggesting tool use had already begun driving genetic evolution. The first intentionally shaped stone tools appear 2. 6 million years ago. These choppers and scrapers required skill to manufacture but remained simple enough that individuals could probably reinvent them.
Populations likely danced around the threshold: cultural knowledge would accumulate, then vanish when groups fragmented or environments shifted. Someone would eventually reinvent lost techniques, allowing them to spread again locally. By 1. 8 million years ago, Homo erectus had crossed decisively. Smaller teeth and guts indicate dependence on processed foods. Shoulder anatomy reflects throwing abilities requiring years of practice to develop.
Erectus spread from Africa across Asia, adapting to diverse environments – something only possible through cultural knowledge. 750,000 years ago at Gesher Benot Ya’aqov, a site in northern Israel, inhabitants controlled fire, quarried basalt slabs with levers, manufactured diverse stone tools, hunted elephants, caught meter-long fish, and processed water chestnuts. No individual could master this knowledge alone in one lifetime. So why did our lineage cross when others haven’t? One reason is that bigger brains capable of cultural learning can’t pay for themselves unless there’s already enough culture to learn. Our ancestors circumvented this problem through two pathways.
First, terrestriality and predation pressure created larger groups with more opportunities for social learning, enriching cultural repertoires without requiring larger brains initially. Second, these larger groups favored pair-bonding strategies. Males offered protection and local knowledge; females gained reliable partners. Pair-bonding expanded kinship networks beyond mother-offspring bonds, creating recognized fathers, siblings, uncles, and grandparents. These relatives provided alloparental care, reducing costs for mothers raising big-brained offspring who required extended childhoods for learning. Recognized kin relationships also connected different groups, allowing cultural information to flow across bands and tribes.
This process created a new kind of animal. We’re not merely smart apes but a species undergoing a major biological transition toward superorganisms. Our survival depends on collective brains – networks of individuals sharing cultural knowledge. Our cooperation, intelligence, and ecological success stem from culture-gene coevolution that has operated for millions of years and continues accelerating today. Understanding human nature requires recognizing we evolved for a world made of culture.
Final summary
In this Blink to The Secret of Our Success by Joseph Henrich, you’ve learned that human success stems from collective learning, not individual brilliance. Our ability to absorb and build on accumulated knowledge creates “collective brains” that develop solutions no single person could discover. Over millions of years, culture and genes coevolved: cooking allowed bigger brains while shrinking our guts, and extended childhoods reflect our dependence on learned skills. Cultural evolution produces adaptations surpassing individual understanding, which is why evolution favored faithful copying of inherited practices over personal reasoning.
Ultimately, we’ve evolved for a world made of culture. Okay, that’s it for this Blink. We hope you enjoyed it. If you can, please take the time to leave us a rating – we always appreciate your feedback. See you soon.
About the Author
Joseph Henrich is the Ruth Moore Professor of Biological Anthropology at Harvard University and has held tenured positions across anthropology, psychology, economics, and human evolutionary biology. A leading researcher in cultural evolution, he is best known for his work on the relationship between culture and human genetics. His work has earned major honors, including the Presidential Early Career Award for Scientists and Engineers and the Hayek Prize. Henrich is also the author of the bestselling The WEIRDest People in the World and the coauthor of Why Humans Cooperate.