In many ways, Homo Sapiens is a very successful species, a lot more so than our ancestors. The usual story about why we are more successful is that biological evolution resulted in us having more enhanced neural hardware. But that story doesn’t add up chronologically. If we look closer, what we see is that it was the cultural institution of religion, and its ability to create large tribes, that made us into modern humans, argue Victor Kumar and Richmond Campbell.
For the first 200,000 years of our existence, Sapiens remained few in number and relatively unaccomplished, confined to a portion of the African continent. Everything began to change roughly 100,000 years ago. Sapiens populations expanded into other parts of Africa and Eurasia. They made the first voyage to Australia an astonishing 50,000 years ago. Western European colonization took longer, beginning only 40,000 years ago. 15,000 years ago, Sapiens entered North America by walking across the temporary land bridge between Siberia and Alaska and traversing sea passages along the northwest coast. Within just 2-3000 years, wanderers established residency near the very tip of South America. Soon enough, Sapiens occupied virtually every terrestrial habitat on the planet.
Sapiens were able to colonize the rest of the world and supplant other human species because they had achieved a new and more complex form of life. Our ancestors were at last dimly but recognizably like us—they had become “behaviorally modern.” They carried out religious rituals, including burying their dead. They adorned their bodies with pigment and jewelry. And they made not just decorations but art—musical instruments, figurines, and the famous, breathtaking paintings preserved in French and Spanish caves. What made all that possible? Many have argued that it has to do with an important turn in our biological evolution. But it was actually religious morality that made us modern humans.
This new period of human history that started around 100,000 years ago witnessed an eruption of imaginative technological innovation. Sapiens were able to make the journey to Australia and other remote islands because they invented sea-worthy vessels and taught themselves the skills to pilot them. They endured in Northern Eurasia and other cold climates through craft. Instead of simply covering themselves with animal pelts as Neanderthals did, our ancestors used sewing needles to produce seamed clothing, which offered more reliable protection from the elements. Large, menacing animals were hunted more safely and effectively using spears, spear-throwers, and bows and arrows. Doubtlessly, these weapons were wielded against other humans too.
To create and operate all of their state-of-the-art technology, our ancestors needed a wealth of brand-new ecological and technical knowledge. Only a small portion of their cognitive and technological achievements can be reconstructed from the archaeological record. But behaviorally modern humans knew how to make tents and other fortified structures, woven baskets, fire hearths, oil lamps, specialized tools for refining their constructions, and much, much more. With clever inventions such as these, Sapiens colonized the world and cleared it out.
The capacity for symbolic thought was not unique to Sapiens and cannot be the secret of our success.
So, how did Sapiens become behaviorally modern? How did they become so knowledgeable and technologically inventive? We propose an answer to this puzzle in our book A Better Ape. Building on a large body of interdisciplinary research, we appeal to a theory about the cultural evolution of tribes, institutions, and religious morality. To grasp this theory and its significance, it will help to understand theories that appeal to biological evolution and why they fail.
It wasn’t biology that made us human
A standard story about behavioral modernity was first articulated by Richard Klein and is often repeated with only slight variations. The standard story is that somewhere between 50-100,000 years ago, biological evolution made humans unique through a novel mutation that enhanced our neural hardware: we gained a novel and unique capacity for “symbolic thought.”
This capacity is supposedly what enabled our ancestors to invent representational art, including paintings of the sort found in European caves. But symbolic thought is also alleged to underlie the explosion of knowledge and technology that appears even earlier in the archaeological record. We managed to colonize the world and out-compete other human species, the story says, because our species alone was blessed with the genetic capacity for symbolic thought.
The standard story is dubious. First, it relies on an implausible theory about the genetic basis of intelligence. In biological evolution, qualitatively new, innate psychological abilities are not the result of a single or even a few genetic mutations. They depend on broad expansion and reorganization of the brain.
Furthermore, recent archaeological evidence seems to sink the standard story. Radiocarbon dating on paintings in three separate caves in Spain places their origin 60,000 years ago. Our species had not yet made it to Europe by then. The paintings in these caves must have been produced by Neanderthals, the only human species known to be living in the area at the time. It follows, then, that the capacity for symbolic thought was not unique to Sapiens and cannot be the secret of our success. Who knows? We may have learned how to paint from our cousins.
A final, even more decisive problem damns the standard story, indeed any theory that attempts to explain the origins of behavioral modern humans by appealing to biological evolution. Genetic evidence shows that Sapiens populations in Africa began to diverge well before they started to become modern. Some humans would then lack the secret genetic trait that supposedly makes the rest of humanity different. The problem is not only that the standard story invites racist classification of humans into superior and inferior “breeds” but that all humans are capable of modern thought and behavior, not just those biologically descended from the first moderns.
At some point in human history bands were knit together into tribes—groups of groups—geographically distributed but linked by ethnicity, dialect, and common purpose.
To be clear, behaviorally modern humans did have the capacity for symbolic thought. And it’s likely that this capacity did play a role in the rise of behaviorally modernity. Like most other interesting human traits, though, it probably evolved gradually rather than suddenly. Moreover, symbolic thought must have pre-dated modernity by several hundred thousand years. If representational art is a litmus test, then Neanderthals had it.
Other capacities were likewise necessary conditions for behavioral modernity: not just symbolic thought but also language and reasoning, cooking and cooperative parenting, morality and theory of mind. However, there is a vast time lag in our history between the origin of these adaptations and the appearance of behavioral modern humans. Something else must have been necessary too. What was it?
It was culture, not biology
For most of history, human populations were limited to small bands of around 150 members. After exceeding that size, a band would split and drift apart, the descendants forgetting their common ancestry. At some point in human history, however, bands were knit together into tribes—groups of groups—geographically distributed but linked by ethnicity, dialect, and common purpose.
Tribes had an edge over bands because they enabled cooperation at a larger scale. One vital benefit was sharing and minimizing risk. Members of a tribe helped each other out in lean times, during droughts and blights. Another benefit is that tribes were more successful in raiding and warfare—along with defense against other groups’ raiding and warfare. In addition, tribes had more leverage for negotiating peace with their neighbors. Peace was often as important as conquest, since it meant forgoing the risk of injury and death. Peaceful relationships between groups also eliminated demilitarized zones and opened access to the resources available there.
But these benefits were uncertain, since internal conflict and strife are more likely to arise in tribes compared to smaller bands. The keys to stable, functioning tribes were social institutions.
The core of any given social institution is a set of interlocking norms—that is, a set of shared and mutually reinforcing social rules that automatically guide behavior, rest on expectations others will follow them, and license sanctions. For example, political institutions consist of a complex web of norms dictating who is permitted to give orders and who must follow them; how disputes must be resolved and who is licensed to issue verdicts; what actions are crimes and under what conditions people are exempt from criminal punishment.
Institutions helped resolve disputes within tribes by creating new norms. They also regulated behavior in new and more effective ways, for example, through ideologies that assigned social roles to members. Institutions policed behavior by inculcating internal pressures and imposing external sanctions. But the decisive adaptive benefit of institutions, and indeed the key to explaining behavioral modernity, was their effect on the cultural evolution of cognitive adaptations.
The explanation for behavioral modernity is cultural rather than biological. By knitting together bands into tribes, social institutions allowed humans to cooperate in ways that made them smarter.
As anthropologist and evolutionary theorist Joseph Henrich argues, a cooperative tribe has a bigger “collective brain.” This ramped up the cultural evolution of knowledge and technology. If there are more people in a group, more new ideas are generated. Ideas are more likely to spread, less likely to be lost. More people means better filtration, selection, and combination of good ideas. What’s more, a greater division of cognitive labor is possible.
So, the explanation for behavioral modernity is cultural rather than biological. By knitting together bands into tribes, social institutions allowed humans to cooperate in ways that made them smarter. That’s how they were able to produce the explosion of knowledge and technology of which we see traces in the archaeological record 100,000 years ago. And that’s how they managed to spread across the world and displace other human species.
Complex cooperation and collective brains are great if you can get them. But how exactly did humans manage to care about and trust those outside their bands? One type of social institution was pivotal.
How religion made us modern
Like other apes, pre-modern humans had a relatively “exclusive” morality. Only fellow band members were seen as fully human; those outside were treated with suspicion and hostility. Exclusive morality facilitated intergroup competition, but it made intergroup cooperation unfeasible.
To form tribes, humans had to see those in other bands as fundamentally like themselves, as moral equals worthy of reciprocity and fairness. The seeds of a more inclusive morality were religious institutions.
Institutions depend on a system of norms, but they are made up of much more than this: rituals, practices, identities, narratives, ideologies. Religious institutions, for instance, consist of norms governing prayer deference, charity, and so on. But they also encompass rituals marking important events in the history of the group; practices of communal meals; identities of priests and supplicants; narratives recounting the origins of ancestors; and ideologies about the supernatural entities and their power over human affairs in this world and the next.
Though religion involves faith, it is not just a matter of belief. It is as much about belonging to a particular community, one that shares a real or imagined history, communal rituals, forms of prayer and worship, narratives about deities and heroes.
By virtue of all these ingredients, religion provided humans with a profound sense of belonging and inherent worth. Though religion involves faith, it is not just a matter of belief. It is as much about belonging to a particular community, one that shares a real or imagined history, communal rituals, forms of prayer and worship, narratives about deities and heroes. All of this contributed to a religious community’s shared “moral identity.” Thus, we who share a religion are of a single flock, children of a common parent. When we are one people, cooperation is compulsory. Refusal to cooperate is betrayal.
So, through religious faith and practice, tribes became resilient in response to the threat of internal conflict. Members of the same tribe could trust one another as members of the same community. Shared religion was a reason to see fellow tribe members as though they were members of the same band or family—to share risks and burdens, fight together, and, most critically, cooperate in the social construction of knowledge and technology.
Religion did not erase the distinction between “us” and “them,” but it shifted who counted as “us.” Thus, while religion expanded our ancestors’ moral boundaries, the boundaries themselves persisted. With the advent of tribes, indeed, moral boundaries became more rigid. It used to be that “we” sometimes needed to cooperate with “them,” for the sake of mate exchange, trade, and temporary alliances. However, once ancestral humans could rely on other bands who were members of the same religiously unified tribes, they no longer had to be so tolerant toward other bands who lacked tribal membership.
Religion was once crucial to human cooperation and knowledge. It remains to be seen whether we can develop institutions that address the social and intellectual challenges we face today.
Deep in human history, our ancestors had to forge knowledge and technology in order to cope with dangerous animals and a naturally fluctuating climate. Today, the environmental challenges are self-imposed. Scientific knowledge can mitigate the severe damage of anthropogenic climate change. But science is not enough. In a culturally and religiously diverse world, we need political institutions that expand moral circles to include the most vulnerable communities and future generations. Only then can we avoid the fate of other human species who once roamed the Earth with us.
This essay is an adapted excerpt from A Better Ape: The Evolution of the Moral Mind and How it Made Us Human (OUP, 2022).