I’m going to let you in on a little secret. Contrary to popular opinion, humans really aren’t that smart. We are lousy at statistics, tend to overgeneralize about the causes of things, quick to falsely accuse people who aren’t in our tribe, and have a long track record mucking up the environments we depend on for our survival.
We’re also prone to deception, believe all kinds of crazy things that have little to no basis in reality, and—if you dropped a random one of us in an unfamiliar place—we’d be more likely to die from eating something toxic than figure out how to live off the land.
From an evolutionary point of view, this is quite puzzling. Aren’t humans the “super species”? Don’t we have the biggest brains and a wicked intelligence that make us the envy of the animal kingdom? The truth is something of a yes and no; humans do have a unique intelligence but not in the way we often think about it.
So if we’re not that smart, what IS the secret of our success as a species? Joseph Henrich, Director of the Culture, Cognition, and Coevolution Lab at the University of British Columbia, offers a compelling and comprehensive answer in his exceptional new book The Secret of Our Success: How Culture is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter. It is an intellectual tour-de-force that offers an overview for the field of cultural evolution. In the rest of this article I’ll lay out the scaffolding of his argument to show how human intelligence doesn’t reside in the individual. It is distributed across the cultural systems that have accumulated a dizzying array of solutions to life-and-death problems across the span of many generations.
In brief form, his argument goes something like this (paraphrased here in my own words):
What does make humans smart is that every one of us “stands on the shoulders of Hobbits.” We are trained in the vast pools of knowledge that have accumulated within the culture of our birth.
Said another way, every person alive today receives a cultural download of stories, practices, tools, and institutions that gradually piled up across the span of ancestors who came before us. There are no rugged individuals in this world. We are each a walking repository of social learnings received from others in our community.
In the vernacular of cultural evolutionary studies, this is called cumulative culture and it is the most pronounced difference between humans and all other social animals. We can see this by making direct comparisons between young human children (who, presumably, have little cultural knowledge built up so far) and other intelligent social animals. Consider a study by Esther Herrmann, Mike Tomasello, and their collaborators at the Institute for Evolutionary Anthropology in Leipzig, Germany. They compared the performances on a battery of cognitive tests for a cohort of 106 chimpanzees, 105 German children, and 32 orangutans—measuring spatial memory of moving objects, discernment of quantities for differently shaped containers, tool selection for performing tasks, and more.
How did the children do? The following graph makes it clear. The human kids were even keel with chimps and orangutans on all of the tasks having to do with general intelligence and problem-solving. We are no better (and no worse, on average) than the common ape.
Where the humans excelled was in the domain of social learning. These were the tasks where a role model performs the complex task first while the test subject watches and learns. The test was designed to see how well the subject gets insights from their role model to help them solve the problem at hand. A dramatic result pops out. Human children—who are still young enough that they haven’t learned very much from culture to make them smart on their own—perform on par with their ape cousins in every way save one: they excel at imitation while their primate peers falter completely.
Add to this the studies showing that children are born with an innate bias to copy the behaviors of high-status and highly competent individuals, are hardwired to enforce social norms immediately after they have learned them, and will pick up extraneous choreographed motions to perform a task even though it is unnecessary. It becomes easy to see that much of our neurological anatomy has been shaped by evolution to help us excel at social learning.
This tells us something very important about what it means to be human. Our uniqueness comes through our ability to quickly assess who in our environment we should learn from and then go about imitating them to learn what they know without all the trial-and-error of having to figure it out on our own. This is how we learn to tie our shoes (Good luck figuring that one out without help… and where did you get the shoes in the first place?). It is how we acquire spoken and written language (Are you going to invent your own version of English with its repository of 1,000,000 defined words? Or will you pick up the words used by those around you?). And it is how we build on the successes of those who came before us to amass warehouses of solutions to problems that are readily taught to the next generation (Want to invent your own “internet of things” or just pick up and use the millions of cool devices and software apps out there that were built by others?).
Henrich takes us through a wealth of examples such as these. He also shares historic examples where European explorers ventured into unknown lands. People who were well supplied and capable at roughing it on their treks died miserable deaths in places that had been inhabited by indigenous populations for hundreds or thousands of years. All because they hadn’t gotten the cultural downloads they would need to survive in those environments.
He starts off with the tale of the HMS Erebus and HMS Terror that left port in June 1845 from the British Isles under the command of Sir John Franklin in search of a Northwest Passage that could energize trade by connecting western Europe to East Asia. They were outfitted with two field tested ice-breaker vessels equipped with state-of-the-art steam engines, retractable screw propellers, and detachable rudders. They also had five years of provisions and were prepared to deal with the harsh winter in the Arctic Ocean. And yet, even with all of these things going for them, the crew was forced to abandon ship in their second year and move onto King Williams Island—where they became fragmented into small groups and forced to the point of cannibalism before all dying eventually.
The crew was in an area where Inuits had lived for thousands of years, some of whom came into contact with the shipwrecked crew during the time they were stranded there. It was a harsh environment where the locals had amassed a repertoire of knowledge about how to build kayaks and igloos, hunt sea animals for food, and scavenge for plants during the brief warm spells of summer. Unfortunately for the British explorers, this body of cultural knowledge was not available to them and they suffered the consequences.
Other expeditions are described, with similar fates, for explorers in the Amazon rainforests (where toxic plants abound) and the desert landscapes of the Australian Outback (with subtle signs for underground water supplies and root vegetables that are edible, but only when properly prepared). In each story the pattern is clear—humans are not the best problem-solvers around, at least not on our own. We depend on the cultural knowledge built up by our ancestors or acquired through friendly trade relations with locals as we venture into strange lands.
This uniquely human strategy of distributed intelligence across the community can be summarized in what Henrich calls the ‘collective brain’—which is the sum total of cultural knowledge, skills, and technologies for a network of people who interact with each other. It is the true source of wealth for economic systems, as argued in another excellent book Why Information Grows by Cesar Hidalgo. Robust measures of information complexity are still being developed to capture the full array of cultural knowledge about things like growing and preparing food, tracking and hunting game, or—in the modern industrial context—skills like software programming or lab techniques for fabricating batches of life-saving pharmaceuticals.
The important thing to keep in mind is that these collective brains arise through the process of cultural evolution. Adaptation and selective fitness give survival advantages to those who know how to learn appropriate survival skills. This includes being successful at navigating the social environments we are born into. It is not necessary for us to know why the things we do are effective—a growing body of research on ritual taboos (also conducted by Henrich and his team) shows that behaviors can be adaptive even when the underlying cause-effect relationships for them are obscure. Said another way, the strategy of When in Rome, do as the Romans do is a good one to follow. Chances are you’ll pick up the correct “adaptive” strategies even when you don’t know which ones they are or why they work.
What struck me most about Henrich’s book was how mature the field of cultural evolution has become. He goes through a wide array of examples, demonstrating his encyclopedic knowledge from years of ethnographic research, about different cultures and how they have solved important survival problems. Combined with a survey of findings in the cognitive and behavioral sciences, a powerful picture emerges for how social learning takes place and why humans are unique in our ability to build on past cultures to increase the size of our bag of tricks.
He makes a convincing case for gene-culture coevolution—that behavioral regimes create social niches, which are able to alter the selection criteria for genetic evolution, and vice versa. Or, in lay terms, culture changes genes and genes change culture. The common story about human evolution is that most of our ancestral line was shaped exclusively by genetic evolution. Only in the last 100,000 to 200,000 years did culture appear on the scene. And so cultural evolution—if recognized at all—is the new kid on the block. This story suggests that genetic evolution created culture in a one-way path of causation.
Henrich’s book (along with books I could mention by Peter J. Richerson and Robert Boyd, Alex Mesoudi, Peter Turchin) makes it plain that this simple story cannot be correct. Paleontological evidence shows clear signs that human anatomy has been changed by culture for several million years on a continuum from small to large structural adaptations that have distinction behavioral components to them. Two examples will give a sense of what I am referring to here. The first is that the length of the human colon is significantly smaller than those for other primates. We have smaller guts because we are able to partially process food through a combination of tool use (cutting it into smaller pieces, pulverizing and tenderizing it, etc.) and cooking (which helps break down the harder-to-digest materials as a kind of external digestion). These changes in human anatomy can be traced back in time at least 2.5 million years.
Another example of gene-culture coevolution can be seen in the cooperative group dynamics that gradually made male and female adults roughly the same size (called dimorphism in the academic literature). Contrast us with gorillas where the male is significantly larger than the female and ponder how genes and culture interacted across the vast span of time since parting ways with our common ancestor—roughly six million years ago—to get a feel for the way social interactions can alter genetic makeup.
It’s opportune that the field of cultural evolution has achieved a state of maturity now, as widespread concerns about population growth, the ecological crisis, and a host of problems in our political and economic systems arose through the mechanisms of gene-culture coevolution. The interplay of social norms, institutions that incentivize or suppress specific behaviors, and the rapid explosion of new technologies both create and exacerbate these problems. And so it will be an understanding of cultural evolution that is necessary to get a handle on them, if indeed we prove capable of doing so at all.
I have written my own call for a science of intentional social change, as have others who affiliate with the Evolution Institute (see this article by David Sloan Wilson, Steve Hayes, Tony Biglan, and Dennis Embry). The three pillars I have identified for this important work are the foundational knowledge from complexity science, cognitive and behavioral science, and cultural evolution. It is a great relief to we are in such able hands for the third pillar in the collective brain comprised of researchers like Joe Henrich. We can all learn from him and the other scholars referenced throughout this article. And we can build our collective brain by forming societies—as we are doing here for the field of cultural evolution—and other organizational structures to coordinate our actions and scale up the application of this vital knowledge for future generations to build upon.
We humans may not be that smart on our own. But we are pretty phenomenal when we put our heads together.