One of the things that makes us uniquely human is our capacity for belief—a capacity with seeds planted very early in our evolutionary process.

Approximately two million years ago, our ancestors endeavored to succeed in a landscape replete with large predators and a myriad of competitors for food and shelter. They were medium-sized, hairless, fangless, hornless, clawless, bipedal, ape-like beings armed with a few rocks and some sticks. Yet they survived, changed, expanded, and eventually became us.

Along the way, we learned to cooperate in new and intensive ways, to innovate, create, imagine, and eventually to believe.

Humans are mammals and primates and hominins, but we are also something distinct from all of these categories. We can philosophize about our place in the world and share it with one another, we can experience existential crisis, and we regularly assume some aspects of life include a transcendent component. Such considerations are mainstays of the many philosophical and theological explanations for what makes us human, but those explanations tend to draw on different sources of knowledge than evolutionary attempts.

What organisms do is a critical part of the definition of who they are. So, an evolutionary definition needs to encompass not just an organism’s materiality but also its behavior, its way of relating to the world.

The human niche

To understand what makes a particular kind of organism distinctive, we need know not just its form and some details of its behavior, but also the way it exists in, and with, the world.

If we are to seek a comprehensive, and effective, evolutionary answer to the question of what makes us human, we need more than just measures of our bodies and behaviors. We need to understand the structure and dynamics of the human niche—one that involves the development of a capacity for, and the practice of, belief.

Today the human niche can be best envisioned as the spatial, ecological, and social sphere that includes all social partners, perceptual contexts, and ecologies of human individuals, groups, and communities and the many other species that live with and alongside humans.

The human niche is the context for the lived experience of humans and their communities. It is where we share social and ecological histories, as well as where the creation of and participation in shared knowledge, social and structural security, and development across the lifespan occurs.

But the human niche also includes the perceptual contexts of human individuals and communities—the ways in which the structural and social relationships are perceived and expressed via behavioral, symbolic, and material aspects of the human experience. In this niche, meaning matters and is evolutionally relevant.

Given the vast complexity in the interlacing of biological, social, and cultural forces, arriving at an understanding of the human niche is daunting. Simplistic, reductionist, and linear notions of what organisms are, and explanations for how they came to be, are insufficient.

If what makes us human is, in part, creating, occupying, and modifying the human niche, then a large part of the answer to “what makes us human?”—and therefore a substantive component of why we believe—lies in the patterns and events that characterized this process across the long durée of our evolutionary history.

More than merely bodies

Over the last million years or so, many populations of our genus contributed behaviors, genes, lifeways, and other aspects to our current incarnation. This dynamic mode of becoming in the world forms the central core of our capacity for being human, for creating, for destroying, for imagining, and for believing. Today all humans are not only the same species, we are the same subspecies, Homo sapiens sapiens. We share more in common with one another genetically than any mammal with a global distribution (and more than many of those with very limited distributions).

The human niche developed slowly at first, picking up pace in the last 3-400,000 years, expanding dramatically in the last 125,000 years, and exploding in complexity over the last 12,000.

We can divide this key phase of our evolutionary history into two basic parts: the initiation of the human niche, and the construction (but not completion) of it. Moving quickly through these two phases sets the baseline from which to develop evolutionary answers to “why we believe.”

Our niche’s initiation lies at the heart of a story of interconnectivity between foraging/nutrition, bodies and brains, caring for young, avoiding predators, and making stone tools in the time period between roughly 2.3 and 1 million years ago.

Making stone tools involves not only the capacity to envision alternative and useful shapes in a stone, but to develop and share the processes for creating those shapes via modifying the stone. This tool-making capacity, including the source selection and sharing of the manufacturing techniques, was likely due to a suite of social learning processes more intensive in our lineage than we see in other social animals.

As these social and technical skills evolved and improved, our lineage developed a level of social learning, a cooperative and collaborative intensity of information transfer greater than other primates and other hominins. This was the initiation of the human niche, focusing on increased cooperation and communication, more collaborative social learning and sharing of information, and opened the doors to more flexible developmental and social systems.

Longer childhoods, better nutrition

Two critical changes occurred at this time. First, as social lives became more complex, the amount time it took young to acquire sufficient information on how to be an effective member of the genus Homo lengthened and humans became cooperative caretakers of their young. Second, as the diversity and quality of their diets increased and nutrition improved, more energy was added to their systems. Combining these two patterns enabled our ancestors to evolve a lengthening of the maturation process, facilitating longer brain growth and more neurological development after birth, creating much more learning capacity and expanding neuroplasticity.

Over time, ours became a thoroughly social and cooperative niche, linked to augmented capacities to collaborate, to share information, to rely on the manipulation of materials outside of our bodies, and to create new solutions to the challenges of the world.

Creativity and compassion

Over the first 1.5 million years of our genus’ history, stone tool technologies began to change and complexify, requiring substantially more training/learning/teaching to produce. Tools became used for an increasing variety of tasks, including food processing and material manipulation. By about 500,000 years ago, many tools are being crafted to a level of extreme symmetry, more than is necessary for function. Almost as if this were an aesthetic choice.

These tools began showing up in clusters across the landscape, as if they were made and cached—or possibly used as markers of some geographical/cultural significance. So tools are not just functional items for tackling the challenges of the world, but imaginatively created materials reflecting something about, and for, their makers.

Recent research demonstrates that this creativity in tool production has broad impact on the capacity for flexibility in behavior, diet, and habitat manipulation—and it also affected the ways in which neurobiology functions. Anthropologist Dietrich Stout and colleagues  are demonstrating that creating such tools impacts particular areas of the brain and patterns of learning, facilitating novel connections across neurobiological systems. These are likely related to a restructuring of the cognitive system and to developing what neurobiologist Michael Arbib calls “the language ready brain.”

By 200,000-400,000 years ago, tool kits are even more diverse, taking on distinctive regional and structural variation. Tools are being made of more materials (including wood and bone), and are developed for large game hunting. The pace of change increases significantly.

By this time, the archeological evidence indicates that our lineage is locked into a lifeway that ubiquitously involves the extensive collection and deployment of materials that we shape, meld to our desires, and use to alter the world. Homo cognition and action are extended into the world by expanding the capacities and confines of our own bodies. The human niche becomes at least partly “cyborg” (a la Haraway) quite deep in our history, hundreds of millennia before smartphones and artificial limbs.

While cooperative parenting began earlier, the behavioral and physiological infrastructure that it provided enabled the development of a heightened compassion and caretaking as a component of the human niche. Archeologist Penny Spikins has documented a wide range of fossil evidence for care of elderly, injured, and infirm individuals, including young with severe developmental diseases. No other species, to our knowledge, exhibits such a pattern of care for others who are injured or ill or aged. This capacity, and its use, is argued to be one of the key reasons why members of our genus were able to spread so widely, across so many new environments, and collaborate so effectively as to develop a range of novel ways of reshaping the world around them. Compassion became a central feature of the human niche.

Symbols, art, and meaning

In the same time period that tools are becoming more complex, we begin to see increasing material evidence for the creation and use of materials that have meaning based in some shared ideology/assumptions/imaginations that are not necessarily tied to the material features/qualities of the item itself. This represents the creation of what many like to call “symbols” or even “art.”

Biological anthropologist Marc Kissel and I recently compiled and published the largest database of all existing potentially “symbolic,” or meaning-laden, artifacts in the early archeological record. These range from vaguely human-shaped modified stones and evidence of lines and simple geometric designs etched into shells and bones, to the manipulation of minerals that can be used as pigments and glues, to evidence of the creation of items of personal adornment (such as beads and the use of paints on bodies and tools).

Over the most recent 300,000-400,000 years, the human niche developed and expanded the realm of imagination and creativity across populations and groups. The pursuit of meaning—altering the world not just to serve specific functional ends, but to represent shared ideas and imaginaries—became a central feature of daily lives. As anthropologist Terry Deacon suggests, this is when our lineage solidified its niche as situated, firmly, in a ubiquitous semiotic ecosystem. Nothing in the human niche is without meaning, and most of that meaning is created, or at least modified, by humans themselves.

You can see how this is critical infrastructure for our capacity to believe.

While we cannot know what many of these artifacts meant to the populations that made them, we can, through our own contemporary filters, identify specific categories of potential meaning. For example, in these last few hundred thousand years, three patterns imbued with meaning emerge and become more and more commonplace: burials, figurines, and cave art.

Since the early days of the genus Homo, behaviors, processes, changes, and actions were ongoing in a creative dynamic, eventually constructing a distinctive niche—a wholly human way of being, with the capacity for imagination, innovation, teaching and learning, caring and communicating, even engaging in conflict. This niche opened new horizons and structures (neurobiologically, ecologically, and behaviorally), which lay the groundwork for the contemporary human capacity for, and practice of, belief.

With the increase in, and eventually ubiquity of, meaning making—material and social—the human niche is infused with a capacity for imagination and innovation. This leads us to infer the emergence of two significant patterns:

First, the ubiquity of imagining novel items/representations/materials and either making them, or altering other things to become them. This capacity is present in a limited form in other animals, but it becomes permanently and ubiquitously part of the human niche.

Second, and drawing on the first, it is likely that by the last 200,000-300,000 years of our history, humans developed the capacity for creating explanations of observable phenomena (such as death, the behavior of other animals, weather, the sun and moon, etc.) that were shared and connected to aspects of the material world but not confined to them. For example, humans did not just connect clouds, thunder, rain, and floods, but they also (eventually) developed explanations for why they happen.

This is what anthropologist Maurice Bloch means when he asserts that over time, humans went from being socially complex transactional beings (as are most social mammals) to groups of organisms who exist simultaneously in both transactional and transcendent realities and who use imagination and belief to reshape themselves and the world around them.

The biological anthropologist Ashley Montagu encapsulates this core facet of the human niche (and here I paraphrase his famous quote):

“The environment (hu)mans make for (themselves) is created through (their) symbol using ability, (their) capacity for abstraction. The symbols, the ideas, are created in the mind . . . but the human animal learns not only to create them, but to project them onto the external world, and there transform them into reality.” (The Human Revolution, 1965).

This we do via our capacity for belief.

Now, let me be absolutely clear. The capacity for belief is not simply an “emergent property” of humanity or something ephemeral floating above the material “reality” of the human. The ability to believe is part of the human system in an equivalent manner that fingers are part of our arms and hands. Fingers are core aspects of the human modified over evolutionary time as to dramatically expand the options for our interface with the world and each other.

Our capacity for belief is akin to our fingers and hands, both core aspects of the human and both critical in the human ability to engage with, and shape, the world—to become in the human niche.

This essay was adapted from one of Agustín Fuentes’ Gifford Lectures from the Spring of 2018. This particular lecture (watch here) was titled “What makes us human? The construction of the human niche and the capacity for belief.” Also, read ORBITER’s interview with Fuentes and fellow Notre Dame prof Celia Deane Drummond, as they discuss their book The Evolution of Human Wisdom (Lexington Books, 2017).

Agustín Fuentes is the Rev. Edmund P. Joyce, C.S.C., Endowed Chair in Anthropology at the University of Notre Dame.