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Recent developments in the study of human prehistory hold clues about our times, our world, and ourselves.

By Deborah Barsky and Jan Ritch-Frel

We can all agree that most people want to know about their origins—spanning from their family and ancestral history and even, occasionally, deeper into the evolutionary story.

Lately, this desire has become more palpable in society at large and even taken on urgent tones as we drift away from the lifestyle patterns and traditions that humans relied on for millions of years toward a technoculture that is highly addictive, and hard to understand or break away from.

But the desire to know the deep past doesn’t translate so easily into understanding, especially since the information we encounter is necessarily filtered by our own sociohistorical context. One of the biggest obstacles to gaining a true understanding of the unfolding of humanity’s past is the way that modern societies foster a superficial understanding of the passage of time.

To delve deeply into human prehistory requires adopting a different kind of chronological stance than most of us are accustomed to—not just a longer period of time, but also a sense of evolution infused by the operating rules of biology and its externalities, such as technology and culture. But exploring the past enables us to observe long-term evolutionary trends that are also pertinent in today’s world, elucidating that novel technological behaviors that our ancestors adopted and transformed into culture were not necessarily better, nor more sustainable over time.

Nature is indifferent to the recency of things: whatever promotes our survival is passed on and proliferated through future generations. This Darwinian axiom includes not only anatomical traits, but also cultural norms and technologies.

Shared culture and technologies give people the ongoing sensation of the synchronization of time with each other. The museums and historical sites we visit, as well as the books and documentaries on the human story, overwhelmingly present the past to their audiences through simultaneous or synchronized stages that follow a kind of metric system of conformity in importance. Human events are charted along the direction of either progress or failure.

The archeological record shows us, however, that even though human evolution appears to have taken place as a series of sequential stages advancing our species toward “progress,” in fact, there is no inherent hierarchy to these processes of development.

This takes a while to sink in, especially if you’ve been educated within a cultural framework that explains prehistory as a linear and codependent set of chronological milestones, whose successive stages may be understood by historically elaborated logical systems of cause and effect. It takes an intellectual leap to reject such hierarchical constructions of prehistory and to perceive the past as a diachronous system of nonsynchronous events closely tied to ecological and biological phenomena.

But this endeavor is well worth the effort if it allows people to recognize and make use of the lessons that can be learned from the past.

If we can pinpoint the time, place, and circumstances under which specific technological or social behaviors were adopted by hominins and then follow their evolution through time, then we can more easily understand not only why they were selected in the first place, but also how they evolved and even what their links with the modern human condition may be.

Taking on this approach can help us understand how the reproductive success of our genus, Homo, eventually led up to the emergence of our own species, sapiens, through a complex process that caused some traits to disappear or be replaced, while others were transformed or perpetuated into defining human traits.

While new discoveries are popularizing the exciting new findings dating as far back as the Middle Paleolithic, the public is typically presented with a compressed prehistory that starts at the end of the last ice age some 12,000 years ago. This is understandable, since the more recent archeological register consists of objects and buildings that are in many ways analogous to our own patterns of living. Ignoring the more distant phases of the shared human past, however, has a wider effect of converting our interpretations of prehistory into a sort of timeless mass, almost totally lacking in chronological and even geographical context.

Among recent breakthroughs reaching the public eye, it has been shown that H. sapiens emerged in Africa much earlier than previously thought, some 300,000 years ago. We now know that the first groups of anatomically modern humans arrived on the northern shores of the Mediterranean Sea as early as 200,000 years ago, a fact that implies a far longer cohabitation of our species in territories already occupied by other forms of Homo, such as the Neandertals and the Denisovans.

Genomic research is progressively telling us something about what our interactions with these species might have been like, proving not only that these encounters took place, but even that they sometimes involved interbreeding and the conceiving of reproductively viable offspring. Such knowledge about our distant past is therefore making us keenly aware that we only very recently became the last surviving species of a very bushy human family tree.

Because of their great antiquity, these very ancient phases of the human evolutionary story are more difficult to interpret and involve hominins who were physically, cognitively, and behaviorally very different from ourselves.

For this reason, events postdating the onset of the Neolithic Period tend to be more readily shared in our society’s communication venues (e.g., museums and schools), while the older phases of human prehistory often remain shrouded in scientific journals, inaccessible to the general public.

But rendering prehistory without providing the complete picture of the evidence is like reading only the last chapter of a book. In this truncated vision, the vast majority of human development becomes a mere prelude before we move on to be amazed at how modern humans began to create monumental structures, sewage systems, and grain storage silos, for example. Just how we got there remains largely undisclosed to the public at large.

Bringing Prehistory Into the Open

The good news is that the rapid development of modern technologies is presently revolutionizing archeology and the ways that scientific data can be conveyed to society. This revolution is finally making ancient human prehistory understandable to a wider audience.

While many of the world’s prehistory museums still display only the most spectacular finds of classical or other “recent” forms of modern human archeology, we are finally beginning to see more exhibits dedicated to some of the older chapters of the human story. By generating awareness, the public is finally awakening to their meaning and significance, enabling themselves to gain a better understanding of the global condition of humanity and its links with the past.

People are finally beginning to understand why the emergence of the first stone tool technologies some 3 million years ago in Africa was such a landmark innovation that would eventually embark our ancestors onto an alternative evolutionary route that would sharply distinguish us from all other species on the planet.

By developing their stone tool technologies, early hominins provided the basis for what would eventually be recognized as a culture: a transformative trait that transformed us into the technology-dependent species we have become and that continues to shape our lives in unpredictable ways.

Archeologists provide interpretations of these first phases of the human technological adventure thanks to the stone tools left behind by hominins very different from ourselves and the contexts in which they are discovered. Among the authors of these groundbreaking ancient technologies are Homo habilis, the first species attributed to our genus—precisely because of their ability to intentionally modify stone into tools—but also other non-Homo primates, such as Paranthropus and Australopithecines, with which they shared the African landscape for many millennia.

Surprisingly, even at a very early stage beginning some 2,600,000 years ago in Africa, scientists have found that some hominins were systematizing stone toolmaking into a coherent cultural complex grouped under the denomination “Oldowan,” after the eponymous sites situated at Olduvai Gorge in Tanzania. This implies that stone toolmaking was being transformed at a very early date into an adaptive strategy, because it must have provided hominins with some advantages. From this time onward, our ancestors continued to produce and transmit culture with increasing intensity, a phenomenon that was eventually accompanied by demographic growth and expansions into new lands beyond Africa—as their nascent technologies transformed every aspect of their lives.

Unevenly through time and space, this hugely significant development branched out into the increasingly diverse manifestations of culture that came to characterize the successive hominin species composing the human family tree. Each technocomplex of the Lower Paleolithic, from the Oldowan to the subsequent Acheulian phase (beginning in Africa some 1,750,000 years ago and then spreading into Eurasia up to around 350,000 years ago), and onward into the Middle Paleolithic and beyond, is defined by specific sets of skills and accompanying behavioral shifts. The tools developed in service of those skills reveal to us the sociocultural practices of the hominins who used them.

Fossilized human remains, and the stone tool technologies they developed, provide the keys to understanding more about ourselves. We can comprehend the changes we observe in the archeological register through time thanks to the bodies of material evidence that tell the story of how humans evolved up to the present. It gives us a frame of reference to recognize the directions that our species might be taking as we move into the future.

To see more clearly, we need to explore how this evolution took place, understanding the transformations diachronically, with change often occurring in nonlinear ways. To do so, we need to leave behind models of path dependence that condition our thinking, leading us to believe that particular aspects recognizable to us through our lens of modernity have a forcing effect of change on the next stages of technosocial development.

Human prehistory widens our conceptual lens by taking into consideration not only innate human traits particular to each phase of hominin ancestral evolution, but also the exterior forces at play throughout the shifting climatic conditions that characterize the long time periods we are considering.

In much the same way as biological evolution, some technosocial innovations can emerge and persist, while others may remain latent in the human developmental repertory, providing a baseline for new creations that can be further developed. If proven to be favorable under specific conditions, selected behavioral capacities can be developed to the point of becoming defining aspects of the human condition.

The latent aspects of technology can, in different regions or time frames, be selected for, used, and refined, leading human groups to choose divergent evolutionary pathways and even triggering technological revolutions: when the changes lead to positive results, they can set off wider cultural developments in the populations that use them.

This way of thinking about technosocial evolution also helps to explain why, more often than not, specific cultural phases generally appear in some kind of coherent successive order through space and time, even though the transitions from one to the other—and the related social processes they engender—can appear blurry as we try to make sense of the archeological evidence.

In this case, it is essential to keep in mind that, through time, different hominins also evolved biologically, as toolmaking and its associated social implications had effects on the evolution of the brain. Developing stone tool technologies provided hominins with an evolutionary edge, enabling them to carve out a unique niche in the scheme of things since it improved their capacity to compete for resources with other kinds of animals. Technological and behavioral developments occurred and evolved in a nonlinear fashion because they were unevenly packed in accordance with each specific paleoecological and community setting.

When we look deeper into our prehistory, it is important to remember that the degree of complexity of human achievements was largely dependent upon particular stages of cognitive readiness. Human technosocial evolution thus appears to have global coherency through time because it reflects the successive phases of cognitive readiness attained on an anatomical level by distinct groups of hominins thriving in different paleoecological settings in diverse geographical regions.

While drawing straight lines between specific hominin species and particular kinds of tools presents some pitfalls, science has already demonstrated that cerebral development was (and is) tightly linked to technological evolution. Specific areas of the brain—the neocortical regions of the frontal and temporal lobes responsible for language, symbolic thought, volumetric planning, and other abstract cerebral functions—were merged with toolmaking. Toolmaking contributed to endowing hominins with unique cerebral capacities—in particular, the abilities to communicate complex abstract notions and create multifaceted sociocultural environments.

Different types of symbolic behavior—the use of a system of symbols to communicate—were employed by different hominin species who found them to be positively adaptive. As a result, cerebral and technological evolution were linked into a co-evolutionary process by which early Homo and subsequent hominins developed idiosyncratic brain structures relative to other animals.

Following the Oldowan, the Acheulian cultural phase is commonly (but not uniquely) linked with the arrival of the successful and widely dispersed Homo erectus. It is during this era that humanity produced some of its most significant technological and behavioral breakthroughs, like fire making and the capacity to predetermine the forms they created in stone. The archeological record attributed to the Acheulian bears witness to advanced technosocial standardization, with the advent of symmetrical tools like spheroids or handaxes attesting to the emergence of aesthetic sensitivity.

The expanding repertory of tool types that appeared at this time suggests that hominins were carrying out more diverse activities, while subtle differences observed in the ways of making and doing began to appear in specific regions, forming the foundation of land-linked traditions and social identities.

The fact that these breakthroughs occurred on comparable timescales in widely separate regions of the globe—South Africa, East Africa, the Middle East, and the Indian subcontinent—underpins that hominins already living in these regions had reached a comparable stage of cognitive readiness and that the specific conditions favoring the emergence of analogous latent technosocial capacities were ripe for the taking. The huge expanses separating the geographical hotbeds suggest that the Acheulian emerged without interpopulational contact.

The explanation that better fits the evidence is that there was a convergent development in the transition from a fairly simple form of Oldowan stone toolmaking to the more complex and sophisticated Acheulian—when Oldowan toolmakers spread out over the planet, they carried the seeds of the Acheulian with them in their minds, their culture, and in the shapes of the stone tools they brought with them.

Indeed, it was only during the later phases of the Acheulian, when we observe denser demographic trends in Africa and Eurasia, that hominin populations would have developed the social networking necessary for technologies to migrate from place to place through direct communication networking.

A similar process of latency and development is in fact observed even in more recent phases of the human evolutionary process—for example, with the emergence of such complex technosocial achievements as the intentional burial of congeners, the construction of monumental structures, the practices of agriculture and animal husbandry, or the invention of writing.

A diachronous approach to time permits more valuable insights from 7 million years of evidence we have of human development. How we structure our understanding of it can create big opportunities to have a better future.

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Deborah Barsky is a researcher at the Catalan Institute of Human Paleoecology and Social Evolution and associate professor at the Rovira i Virgili University in Tarragona, Spain, with the Open University of Catalonia (UOC). She is the author of Human Prehistory: Exploring the Past to Understand the Future (Cambridge University Press, 2022).

Jan Ritch-Frel is the executive director of the Independent Media Institute, and a co-founder of the Human Bridges project.

(Photo Credit: Jebulon / Wikimedia Commons)

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An international group of researchers and data scientists are creating a comprehensive database of the world’s archaeological knowledge—and changing our understanding of humans’ prehistoric heritage.

By Eric Laursen

Archaeology isn’t what it was in Indiana Jones’s heyday. The traditional image of the khaki-clad researcher scrambling over an excavation site with rock hammer and camel-hair brush has been supplemented by aerial and satellite photography, CT scanners and 3D modeling, and lidar that can isolate the smallest details of long-buried settlements. What archaeologists do with the artifacts and data they gather is changing dramatically as well, as they use network science and new software tools to map the complex connections between regional economic networks in the millennia before written history.

With this new, technology-driven approach, researchers can form a far more comprehensive picture of early communities’ ties with other human clusters sometimes thousands of miles away, by examining the goods and raw materials they exchanged and tracing these from their points of origin to the far-flung places where they were abandoned and then rediscovered centuries later. This is yielding additional insights into social inequality and power relations within communities, differences and similarities between communities living next to each other, and patterns of migration and settlement.

“You get more of a sense of a dynamic,” says Tim Kerig, an archaeologist at Kiel University’s ROOTS Cluster of Excellence in Social, Environmental, and Cultural Connectivity in Past Societies, in Germany, “of people coming from other places and how, over the generations, they filled that landscape. So we’re looking at the whole system, over not centuries but millennia.”

Network science is the study of complex relationships—and probable relationships—between physical, biological, social, and cognitive phenomena. Applying network science to archaeology was an idea in the minds of researchers as far back as the 1960s, says Kerig, whose own work focuses on the European Neolithic period—from about 8000 BC to 2000 BC—and the evolution of social inequalities. But while interest grew in succeeding decades, archaeologists lacked the tools to easily collate and analyze the millions of data points that had been gathered over many decades. The few efforts to do so proceeded punishingly slowly, on top of which, there was less interest at the time in exploring the connections that material and economic exchanges between far-flung communities could reveal.

“Sociological questions were mostly answered by looking at goods that were found in graves—the ‘sphere of kings’—which tended to be highly valued luxury items,” Kerig says, while archaeologists were less interested in “the daily stuff”: fragments of flint or stone objects or implements that made up the fabric of most people’s everyday lives. This was partly due to an overabundance of these humbler items. “Don’t forget that at a Stone Age site in Denmark, for example, you might have 100,000 artifacts to deal with, and they all look to most of us exactly the same.”

“Big Exchange” is the name of a project that an international cluster of scholars and data scientists, including Kerig, launched in 2020 with the aim of using digital tools to break down the barriers to applying network science to archaeology. The most critical hurdle they faced was overspecialization. Traditionally, archaeologists have focused on specific objects or raw materials—amber, obsidian, jade, flint, other metals—rather than the totality of findings at a given site, which prevented them from seeing the totality of that community’s networks of exchange. Big Exchange’s first objective is to create a database that collates all these materials and makes them available for more sophisticated, cross-referenced study and analysis.

“The approach of our project is to include all recordable raw materials, their find locations and places of origin in the analysis for the period from the end of the Middle Stone Age [or Mesolithic, 10,000 years ago,] to Antiquity,” Johanna Hilpert, a Big Exchange postdoc researcher at the ROOTS Cluster, told Phys.org in July 2023. “This can only be done by means of network analysis and with AI [artificial intelligence].”

A Deeper, More Granular Understanding

As of July 2023, Big Exchange has already collated data from 6,000 sites from which millions of artifacts have been recovered, and expects to complete the task in another two and a half years. The objective is to collect and digitize as much information as possible and establish classifications for all of it—for example, by site location, time period, and how far a material was found from its place of origin.

Establishing the database itself has not proven to be an easy task. Some of the source data for Big Exchange had already been digitized in some form; some of it is being digitized for the first time. It quickly became clear that the way researchers analyze these findings has changed over the past hundred years, “and so you can imagine all kinds of technical problems,” Kerig says.

Big Exchange used PostgreSQL, a common relational database management system. Working bottom-up, they started by inputting the individual datasets, developing the formal structure of the database, including comparisons of attributes and concepts, as they went along. Once all existing data is integrated, the database can be used by researchers working to reconstruct long-vanished economic and social networks.

But the project is already producing results. One study, published this year in the journal Antiquity, analyzed the geographic expansion of one of the most studied Neolithic cultures, the Linear Pottery culture (LPC) that extended from roughly the present-day Netherlands to the Black Sea and flourished from about 5500 BC to 4500 BC.

Applying a heterogeneous information network (HIN) analysis—a sophisticated graphic model that can map the relationships between diverse but interconnected sets of data—to raw materials in circulation at the time, researchers were able to detect differences in material culture between the northwest subgroup of the LPC and other subgroups that surrounded it. For example, sites associated with the northwest group contained no shells of Spondylus, a bivalve mollusk, that were a prestige good in Neolithic burial sites farther east in the Carpathian Mountains.

Previously, researchers assumed this was because of poor conditions for preservation in the area that the northwest group occupied. But HIN mapping revealed that the region lacking Spondylus shells was much wider than the area where preservation was difficult, and that it contained a good supply of flint that had originated much farther west. This suggested that the blend of raw materials used by the northwestern group wasn’t dictated by local availability, but by cultural or economic choice, linking the group to exchange networks that other LPC subgroups didn’t participate in, in spite of the fact that those other subgroups were close neighbors.

The HIN analysis allowed the Big Exchange researchers to develop a deeper, more granular understanding of the LPC—a culture that archaeologists thought they had already acquired a detailed knowledge of—that teases out previously undetected cultural and economic differences between subgroups.

Combining Big Exchange’s practice of looking at all the objects found at a particular excavation site with its focus on networks of exchange, the project is also producing new insights into inequality and power relations within groups. “The meaning of these objects changes depending on the regional and chronological context,” says Kerig. For instance, a fragile item found in a protective leather wrapping, with no evident practical use, will tend to come from a greater distance than more common items, indicating that a distant origin and the difficulty of obtaining it conferred a prestige value on the object. A large finding of such objects would indicate that an elite was emerging in the community connected with that site.

Clearing Away Cultural Bias

Already, however, the researchers are confronting limitations in the data they are collecting: limitations that point to larger issues. The vast majority of known archaeological sites outside the Americas are in Europe and, to a lesser extent, the Near East—a comparatively small area—with far fewer elsewhere, Kerig notes. Exchange networks in the Neolithic era certainly stretched far beyond these two regions. The more connections revealed by projects like Big Exchange, the more urgent will be the need to expand excavation and recovery into other parts of Eurasia; one goal of Big Exchange is to offer guidance as to where the most promising sites might be located.

Cultural bias is another issue. “We are not only collating datasets; we are also collating the authors of the datasets,” Kerig says. For some sites that he and his colleagues wanted to include, no actual data is available; perhaps research began in those areas but then was interrupted, or else documentation was lost during wartime, and all that remains are published or unpublished writings, often with less quantitative content and heavily informed by the preconceptions of the time. While evidence can be teased out of these sources, it has to be handled with care.

“These more qualitative things are very, very important—perhaps worth more than the actual datasets,” says Kerig. “But we meet regularly to discuss these things, and it’s new for all of us. I would expect that we will get a bloody nose if we don’t.” This is where technologies like artificial intelligence could become more useful in the future, by helping researchers to tease out valid observations from the mass of culturally biased material.

Big Exchange’s most pressing challenge, however, is keeping the project going. The painstaking work of inputting and mapping data into the project’s evolving database is currently being carried out by students at the Kiel ROOTS Cluster. “It’s a very labor-intensive thing,” says Kerig. He is now looking for a long-term home for Big Exchange that can host its growing data-analytic treasure trove and make it available to archaeologists and other investigators in coming decades.

But he remains hopeful about Big Exchange’s future. “I am pretty sure that something is coming in in this direction,” he says.

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Eric Laursen is an independent journalist, historian, and activist. He is the author of The People’s Pension, The Duty to Stand Aside, and The Operating System. His work has appeared in a wide variety of publications, including In These Times, the Nation, and the Arkansas Review. He lives in Buckland, Massachusetts.

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Today’s hot-button issue is actually as old as the human race.

By Deborah Barsky

We live in an era of mass migration. According to the United Nations’ World Migration Report 2022, there were 281 million international migrants in 2020, equaling 3.6 percent of the global population. That’s well over twice the number in 1990 and over three times the estimated number in 1970. In countries that receive them, migrants are often blamed, rightly or wrongly, for everything from higher crime to declining wages to social and cultural disruption.

But the frictions provoked by migration are not new problems; they are deeply embedded in human history and even prehistory. Taking a long-term, cultural-historical perspective on human population movements can help us reach a better understanding of the forces that have governed them over time, and that continue to do so. By anchoring our understanding in data from the archeological record, we can uncover the hidden trends in human migration patterns and discern (or at least form more robust hypotheses about) our species’ present condition—and, perhaps, formulate useful future scenarios.

Globalization in the modern context, including large-scale migrations and the modern notion of the “state,” traces back to Eurasia in the period when humans first organized themselves into spatially delimited clusters united by imaginary cultural boundaries. The archeological record shows that after the last glacial period—ending about 11,700 years ago—intensified trade sharpened the concept of borders even further. This facilitated the control and manipulation of ever-larger social units by intensifying the power of symbolic constructions of identity and the self.

Then as now, cultural consensus created and reinforced notions of territorial unity by excluding “others” who lived in different areas and displayed different behavioral patterns. Each nation elaborated its own story with its own perceived succession of historical events. These stories were often modified to favor some members of the social unit and justify exclusionist policies toward peoples classified as others. Often, as they grew more elaborate, these stories left prehistory by the wayside, conveniently negating the common origins of the human family. The triggers that may first have prompted human populations to migrate into new territories were probably biological and subject to changing climatic conditions. Later, and especially after the emergence of our own species, Homo sapiens, the impulse to migrate assumed new facets linked to culture.

From Nomadism to Migration

The oldest migrations by hominins—the group consisting of humans, extinct human species, and all our immediate ancestors—took place after the emergence of our genus, Homo, in Africa some 2.8 million years ago and coincided roughly with the appearance of the first recognizably “human” technologies: systematically modified stones. Interestingly, these early “Oldowan” tool kits (after the Olduvai Gorge site in Tanzania) were probably made not only by our genus but also by other hominins, including Paranthropus and Australopithecines.

What role did stone tools play in these early steps along our evolutionary path? Archeology tells us that ancient humans increasingly invested in toolmaking as an adaptive strategy that provided them with some advantages for survival. We see this in the noticeable increase in the geographical distribution of archeological sites beginning about 2 million years ago. This coincided with rising populations and also with the first significant hominin migrations out of Africa and into Eurasia.

Toolmaking in Oldowan technocomplexes—distinct cultures that use specific technologies—shows the systematic repetition of very specific chains of operations applied to stone. This suggests that the techniques must have been learned and then incorporated into the sociobehavioral norms of the hominin groups that practiced them. In fact, there are similarities between the first Eurasian stone tool kits and those produced at the same time in Africa. Technological know-how was being learned and transmitted—and that implies that hominins were entering into a whole new realm of culture.

While the archeological record dating to this period is still fragmentary, there is evidence of a hominin presence in widely separated parts of Eurasia—China and Georgia—from as early as 2 million to 1.8 million years ago; we know that hominins were also present in the Near East and Western Europe by around 1.6 million to 1.4 million years ago. While there is no evidence suggesting that they had mastered fire making, their ability to thrive in a variety of landscapes—even in regions quite different from their original African savannah home—demonstrates their impressive adaptive flexibility. I believe that we can attribute this capacity largely to toolmaking and socialization.

How can we envision these first phases of human migrations?

We know that there were different species of Homo (Homo georgicus, Homo antecessor) and that these pioneering groups were free-ranging. Population density was low, implying that different groups rarely encountered each other in the same landscape. While they certainly competed for resources with other large carnivores, this was probably manageable thanks to a profusion of natural resources and the hominins’ technological competence.

From around 1.75 million years ago in Africa and 1 million years ago in Eurasia, these hominins and their related descendants created new types of stone tool kits, referred to as “Acheulian” (after the Saint-Acheul site in France). These are remarkable for their intricacy, the standardization of their design, and the dexterity with which they were fashioned. While the Acheulian tool kits contained a fixed assortment of tool types, some tools for the first time displayed regionally specific designs that prehistorians have identified with specific cultural groups. As early as 1 million years ago, they had also learned to make fire.

Acheulian-producing peoples—principally of the Homo erectus group—were a fast-growing population, and evidence of their presence appears in a wide variety of locations that sometimes yield high densities of archeological finds. While nomadic, Acheulian hominins came to occupy a wide geographical landscape. By the final Acheulian phase, beginning around 500,000 years ago, higher population density would have increased the likelihood of encounters between groups that we know were ranging within more strictly defined geographical radiuses. Home base-type habitats emerged, indicating that these hominin groups returned cyclically to the same areas, which can be identified by characteristic differences in their tool kits.

After the Oldowan, the Acheulean was the longest cultural phase in human history, lasting some 1.4 million years; toward its end, our genus had reached a sufficiently complex stage of cultural and behavioral development to promulgate a profoundly new kind of cognitive awareness: the awareness of self, accompanied by a sense of belonging within a definable cultural unit. This consciousness of culturally based differences eventually favored the separation of groups living in diverse areas based on geographically defined behavioral and technological norms. This was a hugely significant event in human evolution, implying the first inklings of “identity” as a concept founded on symbolically manufactured differences: that is, on ways of doing or making things.

At the same time, the evidence suggests that networking between these increasingly distinct populations intensified, favoring all sorts of interchange: exchange of mates to improve gene pool variability, for example, and sharing of technological know-how to accelerate and improve adaptive processes. We can only speculate about other kinds of relations that might have developed—trading of stories, beliefs, customs, or even culinary or medicinal customs—since “advanced” symbolic communicative networking, emblematic of both Neandertals and humans, has so far only been recognized from the Middle Paleolithic period, from 350,000 to 30,000 years ago.

Importantly, no evidence from the vast chronological periods we have outlined so far suggests that these multilayered encounters involved significant inter- or intraspecies violence.

That remained the case moving into the Middle Paleolithic, as the human family expanded to include other species of Homo over a wide territorial range: Neandertals, Denisovans, Homo floresiensis, Homo luzonensis, Homo naledi, Nesher Ramla Homo, and even the first Homo sapiens. Thanks to advances in the application of genetic studies to the paleoanthropological record, we now know that interbreeding took place between several of the species known to have coexisted in Eurasia: humans, Neandertals, and Denisovans. Once again, the fossil evidence thus far does not support the hypotheses that these encounters involved warfare or other forms of violence. By around 150,000 years ago, at least six different species of Homo occupied much of Eurasia, from the Siberian steppes to the tropical Southeast Asian islands, and still no fossil evidence appears of large-scale interpopulational violence.

Some 100,000 years later, however, other varieties appear to have died away, and Homo sapiens became the only Homo species still occupying the planet. And occupy it they did: By some time between 70,000 and 30,000 years ago, most of the Earth’s islands and continents document human presence. Now expert in migrating into new lands, human populations flourished in constantly growing numbers, overexploiting other animal species as their dominion steadily enlarged.

Without written records, it’s impossible to know with any certainty what kinds of relationships or hierarchies might have existed during the final phases of the Paleolithic. Archeologists can only infer from the patchy remains of material culture that patterns of symbolic complexity were intensifying exponentially. Art, body decoration, and incredibly advanced tool kits all bear witness to socially complex behaviors that probably also involved the cementing of hierarchical relationships within sharply distinct social units.

By the end of the last glacial period and into the Neolithic and, especially, protohistoric times—when sedentarism and, eventually, urbanism, began but before written records appear—peoples were defining themselves through distinct patterns and standards of manufacturing culture, divided by invented geographic frontiers within which they united to protect and defend the amassed goods and lands that they claimed as their own property. Obtaining more land became a decisive goal for groups of culturally distinct peoples, newly united into large clusters, striving to enrich themselves by increasing their possessions. As they conquered new lands, the peoples they defeated were absorbed or, if they refused to relinquish their culture, became the have-nots of a newly established order.

An Imagined World

After millions of years of physical evolution, growing expertise, and geographic expansion, our singular species had created an imagined world in which differences with no grounding in biological or natural configurations coalesced into multilayered social paradigms defined by inequality in individual worth—a concept measured by the quality and quantity of possessions. Access to resources—rapidly transforming into property—formed a fundamental part of this progression, as did the capacity to create ever-more efficient technological systems by which humans obtained, processed, and exploited those resources.

Since then, peoples of shared inheritance have established strict protocols for assuring their sense of membership in one or another national context. Documents proving birthright guarantee that “outsiders” are kept at a distance and enable strict control by a few chosen authorities, maintaining a stronghold against any possible breach of the system. Members of each social unit are indoctrinated through an elaborate preestablished apprenticeship, institutionally reinforced throughout every facet of life: religious, educational, family, and workplace.

Peoples belonging to “alien” constructed realities have no place within the social unit’s tightly knit hierarchy, on the assumption that they pose a threat by virtue of their perceived difference. For any person outside of a context characterized by a relative abundance of resources, access to the required documents is generally denied; for people from low-income countries seeking to better their lives by migrating, access to documents is either extremely difficult or impossible, guarded by sentinels charged with determining identitarian “belonging.” In the contemporary world, migration has become one of the most strictly regulated and problematic of human activities.

It should be no surprise, then, that we are also experiencing a resurgence of nationalistic sentiment worldwide, even as we face the realities of global climate deregulation; nations now regard the race to achieve exclusive access to critical resources as absolutely urgent. The protectionist response of the world’s privileged, high-income nations includes reinforcing conjectured identities to stoke fear and sometimes even hatred of peoples designated as others who wish to enter “our” territories as active and rightful citizens.

Thanks to the very ancient creation of these conceptual barriers, the “rightful” members of privileged social units—the haves—can feel justified in defending and validating their exclusion of others—the have-nots—and comfortably deny them access to rights and resources through consensus, despite the denigrating and horrific experiences these others might have undergone to ameliorate their condition.

Incredibly, it was only some 500 years ago that an unwieldy medieval Europe, already overpopulated and subject to a corrupt and unjust social system, (re)discovered half of the planet, finding in the Americas a distinct world inhabited by many thousands of peoples, established there since the final phases of the Upper Pleistocene, perhaps as early as 60,000 years ago. Neither did the peoples living there, who had organized themselves into a variety of social units ranging from sprawling cities to seminomadic open-air habitations, expect this incredible event to occur. The resource-hungry Europeans nevertheless claimed these lands as their own, decimating the original inhabitants and destroying the delicate natural balance of their world. The conquerors justified the genocide of the Indigenous inhabitants in the same way we reject asylum seekers today: on the grounds that they lacked the necessary shared symbolic referents.

As we step into a newly recognized epoch of our own creation—the Anthropocene, in which the human imprint has become visible even in the geo-atmospheric strata of our planet—humans can be expected to continue creating new referents to justify the exclusion of a new kind of migrant: the climate refugee. What referents of exclusion will we invoke to justify the refusal of basic needs and access to resources to peoples migrating from inundated coastal cities, submerged islands, or lands rendered lifeless and non-arable by pollutants?

Click here to read the article on Resilience.org.

Deborah Barsky is a researcher at the Catalan Institute of Human Paleoecology and Social Evolution and associate professor at the Rovira i Virgili University in Tarragona, Spain, with the Open University of Catalonia (UOC). She is the author of Human Prehistory: Exploring the Past to Understand the Future (Cambridge University Press, 2022).