Roma Termini: why cities both make us and break us as a species
The eternal tradeoff of dynamism and fertility in urban centers
For what shall it profit a man, if he shall gain the whole world, and lose his own soul? -Matthew 16:26, KJV
South Koreans innovate and produce everything. All those miracle skin care products, k-pop, k-drama, that buzzy blockbuster that wins the Oscar, the only smartphone line that competes with the iPhone anymore, your dependable car, your washer and dryer that never quit, the flat screen TV in every hotel room. The only thing Koreans don’t make… is more Koreans. In the space of a human lifetime, the South Korean populace has gone from some 20% urban to over 90%. Korea has attained a quality of life that in material terms has few rivals. And with all that societal-level prosperity: the progress, the innovation and the productivity has come an immeasurable toll payable at the individual level: the dwindling or extinction of millions of human lineages. Families who are not childless today often have only a single child. At current rates, by 2100, Korea’s population will fall by half. Korea is an extreme example, but this dynamic is playing out all over the developed world.
Plotting women’s total fertility rate against percent urbanization yields an inverse correlation of -0.48, meaning that the more urbanized a nation, the fewer children born per woman. Today, the urbanization of nations below 2.0 total fertility averages 70%, while that of nations above 2.0 is 52%.
Where we flock to dynamic cities, we compete and collaborate, we prosper, we innovate, and we change human society the world over, innovation by innovation. And in the process, our fertility collapses. In Roman times, it wasn’t immediate fertility so much as that the numerous children of the urbs, even the most privileged ones, didn’t survive at the same rates as their counterparts in the sleepier hinterlands. Today we don’t even conceive them. Cities are an incredibly recent phenomenon in our history (our species has been anatomically modern for 200,000 years, during just 9,400 of which any humans, and then usually only a tiny minority, have dwelt in cities). I have reflected previously on the striking finding that two millennia on, the illustrious inhabitants of one of the most culturally influential societies to grace our planet, the Roman Empire, have fingerprints on nearly every aspect of modern society, and yet left nary a genetic trace even on the peninsula that Rome calls home. Here, I circle back to that line of thinking and reflect on why the comparatively plodding pace of human evolution is no match for the breakneck clip at which we drive cultural evolution when we come together in urban centers. Cities make us. Their uniquely unlimited possibility plays on our innate drive for status and material success (assured routes to improved reproductive outcomes elsewhere). And they break us, material success in the world’s cities coming at a cost that can be enumerated in tiny empty desks, desolate playgrounds and former maternity wards being converted into facilities for the burgeoning elderly population.
In the film Gladiator, set during the father and son reigns of Emperors Marcus Aurelius and Commodus, the only other member of the imperial family featured is Lucilla, daughter to the elder emperor, sister to the younger. In actuality though, over time, the historical Commodus had over a dozen siblings. But most of them, including his own twin brother, did not live to adulthood. Besides Commodus and Lucilla, their sisters Annia and Vibia survived to reproduce; but of Marcus Aurelius and his wife Faustina the Younger’s thirteen children, nine were not so lucky. So two in three children of the most powerful couple in the largest city in the world expired young, sobering testament to the non-negotiable caprices of biological forces in the lives of premodern people. Marcus Aurelius’ offspring lived and died subject to the same whims of nature as any peasant spawn. Roman medicine was primitive at best and counterproductive at worst. Ancient civilization had mastered arcane aspects of metallurgy, architecture and agriculture, but physiology, anatomy and immunology remained as mysterious to the Romans as they had been to their Pleistocene forebears. The conquest of human biology, and therefore scientific medicine and public health would have to wait all the way until humanity's most recent few centuries of history.
In actual fact though, no matter how elite their pater, Marcus Aurelius’ children were subject to even more inclement forces than those faced by their peasant contemporaries in the countryside of Latium. Though they are approximations at best, the scholarly literature holds that about half of Roman children survived to adulthood, a sight better than Commodus’ sibling cohort fared. And the sorry outcome of most of Marcus Aurelius’ issue might well represent a best case for the children born to the Roman urbs. The Emperor’s offspring would have spent much of their time in Palatine Hill’s sumptuous, airy palaces, rather than the fetid Suburra below, a vast slum occupied by the Roman underclass. And unlike many inhabitants of the Roman Empire, the emperor’s children would have fed well on a rich and varied diet of meat, fish, fruit, vegetables and grains. But even still, the Roman elite were surrounded by the second-century city’s teeming masses, its million inhabitants crowding in around them. At 13.7 km2, Antonine Rome recorded a population density of 72,000 people/km2. Our densest modern city is Manila, at 43,000/km2. Manhattan, this country’s idea of dense, sits at 28,000 people/km2. The visible squalor and inescapable stench that dominated antiquity’s megacities is surely beyond our imagining. Perhaps the only realistic sense we might obtain would come in slums like Dharavi in Mumbai.
Life in the premodern world was often short and brutal; plague, famine and war always lurked. As early as 3000 BC you see evidence of this, with the collapse of village life all across Europe upon introduction of plague from the east (a recurring event whose relentlessness was seemingly dictated by the massive reservoir of livestock animals incubating pathogens on the Eurasian steppe). Ancient people knew though that the toll of plague and disease impacted cities more than the hinterlands. Fresh country air, in place of the dusty and polluted miasma that suffused the urban slums, was understood to be salubrious. Later, better transportation allowed for the emergence of suburbs, releasing yet more pressure on the urban core, with the poor no longer condemned to live in cheek-by-jowl dystopian conditions.
But for all its rankness and grime, the ancient city was the hinge of civilization, the nexus around which the literate classes who recorded their era’s enduring histories gathered and indeed flourished. An increasingly urban engine of creativity drove intellectual, economic and political power. These were the human cultures that would not only reshape their age but reach across millennia to touch our own in countless crucial ways worked out in the city’s taverns, public squares, courts and academies. Historian of religion Rodney Stark wrote Cities of God to document the fundamentally urban character of early Christianity; the term pagan was synonymous not just with unbelievers, but also with rural peasants. The future was to be determined by the direction Roman culture took in its cities, not in the vast rural hinterlands. But this urban cultural ferment came with a punishing biological mortgage: the men and women with their fingerprints all over the world of ideas left no imprint on posterity genetically. If ancient cities were dynamic engines of culture, birthing whole new civilizational social structures, it was almost as if for fuel they required vast graveyards’ worth of spent human lineages
Marcus Aurelius’ milieu, the Greco-Roman world of Classical Antiquity, is a perfect example of this reality. For the Greeks, the city, the polis, was the state. Most imperial subjects and citizens of the Roman Empire were peasants, but the imperium under which they lived was operationally a Mediterranean-wide collection of cities bound together by roads and seaways, administered by bureaucrats and gentry. It is these cities that preserved records for our research, and it is they that produced texts like the New Testament that have proved foundational to the course of Western civilization. But we can now also finally examine ancient DNA from these dynamic cities that went from strength to strength, the lynchpins and anchors of the ancient world’s most powerful state. And that DNA paints a very different picture, one of ceaseless defeat in the face of pathogens.
The roads to extinction
A common idea runs that before the advent of trains, planes and highways, the average human rarely left their home village. This model imagines the world of the peasant delimited by field, farmhouse and market. A timeless scene marked generation after generation by little more variety than the change of seasons, a world of sedentism after the close of the forager’s age.
But this was not the only model. The remains of an ancient individual known to archaeology as the Amesbury Archer were buried three miles from Stonehenge more than 4,300 years ago, some two millennia after the arrival of settled farmers to Britain. His burial goods indicate that he was of high status. Though he died in Copper Age Britain, the isotopes in his bones indicate that he reached manhood on the European continent, near the Alps, 750 km away for a bird, and far longer of course for an ancient archer traversing ocean, river and valley floor. More recently, ancient DNA has also produced evidence of second and third cousins buried 5,000 years ago in gravesites at completely opposite ends of the Eurasian steppe, in Mongolia and Eastern Europe, a startling illustration of the extent of early nomads’ appetite for ultra-long-distance migration. A man or woman born on the Pontic steppe at Europe’s eastern edge might by the end of life be resident (and thus eventually buried) in the distant summer pastures of Mongolia’s Altai.
Nomadic mobility is a natural consequence of their way of life, driving vast herds, followed by caravans of carts. They may not have rivaled the speed of Victorian-era trains, but even the annual life cycle of pastoralist peoples could often entail migration between winter and summer pastures hundreds of kilometers apart. With rare exceptions, farmers do not move with the seasons, they merely endure the seasons moving over them. Though initial phases of agriculture’s expansion involve migration and long-distance colonization, farming societies rapidly reach static equilibrium, where cultural evolution slows to a crawl as a population comes into balance with the local “carrying capacity.” Faced with both climatic volatility that threatened famine and rent-seeking elites wreaking political instability, peasants grasped for stasis in a bid for survival; even today, farmers remain notoriously conservative because that was the surest path to survival in the premodern world. European peasants’ conservatism famously retarded the adoption of potatoes by centuries.
Both after the end of the Ice Age 11,700 years ago and up to when the Industrial Revolution of the 19th century dawned, these peasants formed the backbone of human societies. To a first approximation, to be human was to be a peasant. In all ancient societies, elites trusted that land ownership was the most stable and secure form of wealth given that cultivators’ economic production was the foundation of civilization. But despite the primacy of the peasant as civilization’s bedrock, by the time text preserves narrative history, cities were the nodes around which civilization progressed, evolved and eventually attained unprecedented heights of complexity.
The first civilization of Sumer was not a single polity, but a commonwealth of cities, from Ur in the south to Kish in the north. If farmers were the sturdy body of agricultural civilization, cities were its head. After Sumer came Babylonia, named for its capital city, and then the Greeks, whose loyalty to their polis, their cities, transcended any national identity. Thus the society that became the Roman Empire was heir to a 3,000-year legacy of literate urban civilization beginning in Mesopotamia, and the Romans, like their Greek predecessors, remained a people focused on their city. Republican Rome was organized around “tribes” that voted in blocs. Most of these were rural, located outside Rome proper (just two urban tribes represented the city’s proletariat and these had minimal voting power). But the rural tribes' political leadership flexed their power within the walls of the city, with their senators and tribunes holding forth in Rome’s Forum, charting the direction of the Republic from the urban apartments where they held court with their clients.
At its peak, somewhere between 10-20% of the citizens of the Empire lived in cities; a threshold not regained in Europe until the 1800’s. In Italy, as much as 20-30% of the population may have been urban, concentrated around several large cities like Rome, Syracuse and Ravenna. At their peaks, Rome in the west and Constantinople in the east may have topped a million residents each. These numbers were entirely unsustainable on the backs of the agricultural production in their hinterlands alone. In later centuries, Rome relied on grain shipped from North Africa, Constantinople on wheat from Egypt. Complex agricultural civilizations like Rome broke beyond the self-sustaining autarky of village life, their maritime routes and roads teeming with manufactured goods and produce, a sophisticated network that brought housewares and fine wine even to remote Britain. The collapse of the western Roman Empire in the centuries after 400 AD was the implosion of an entire economic system; archaeologist Bryan Ward-Perkins famously publicized the finding that pollution in British ponds did not reach Roman levels again until the Industrial Revolution.
While the Greeks are famed in the ancient world for their achievements in abstract analysis, and for pioneering mathematics, science and philosophy, the Romans were a more practical people, introducing aqueducts, domes and long straight cobblestone roads across their empire. Though Roman roads were originally built with strictly military ends in mind, facilitating the march of legions from one end of the Empire to the other, in peacetime they were byways of trade and transit. Roman engineering prowess was such that even 1,600 years after the Empire departed Britain, motorists still use 10 Roman roads on that island.
Though the Roman transport infrastructure, from roads and canals to vast fleets of ships, their cargo holds bursting with grain, was instrumental in moving goods from one end of the Empire to the other, it also crucially facilitated the mass migration of peoples. By the time of the Empire, as many as 40% of the grave sites in Rome bore epitaphs written in the Greek alphabet, and second-century AD poet Juvenal complained of foreign influence in the city, quipping that the “Syrian Orontes has flowed into the [Roman] Tiber.” The textual and archaeological evidence is clear; after Juvenal’s time, Rome grew more foreign still, with even the rulers of the Eternal City all hailing from the Empire’s periphery after 200 AD. And the DNA supports this contention; the reality the ancient Romans recorded comports with the genetic evidence.
