Syrian Orontes has long since dried up, to be replaced by the Tiber once more


The paper is out, Ancient Rome: A genetic crossroads of Europe and the Mediterranean:

Ancient Rome was the capital of an empire of ~70 million inhabitants, but little is known about the genetics of ancient Romans. Here we present 127 genomes from 29 archaeological sites in and around Rome, spanning the past 12,000 years. We observe two major prehistoric ancestry transitions: one with the introduction of farming and another prior to the Iron Age. By the founding of Rome, the genetic composition of the region approximated that of modern Mediterranean populations. During the Imperial period, Rome’s population received net immigration from the Near East, followed by an increase in genetic contributions from Europe. These ancestry shifts mirrored the geopolitical affiliations of Rome and were accompanied by marked interindividual diversity, reflecting gene flow from across the Mediterranean, Europe, and North Africa.

If you don’t have access to the paper, the supplements are very good, with lots of visualizations.

The figure above summarizes the main clear dynamic:  the period of cultural and genetic cosmopolitanism of the Imperial period turned out to be ephemeral. The authors express a bit of surprise that the cosmopolitanism of Roman genetics during the Imperial period seems to manifest itself in an ‘eastward’ shift, and hypothesize that this is due to the greater population density of the eastern provinces.

This is almost certainly true.

The western focus of the early Roman Empire was somewhat at odds with the reality that the wealthiest and most populous domains were located in the eastern Mediterranean. The shocks of the 3rd-century resulted in an eastward orientation because that’s where the largest cities and tax base were. The Greek-speaking east, in particular, continued to provide the intelligentsia even throughout the Classical period, and due to the wealth of eastern cities, it is plausible that the mercantile elite of the capital often had eastern roots. The prevalence of Greek inscriptions in burials also is strongly indicative of eastern people in the capital.

That’s all to be expected. But what happened after the fall of Rome? The evidence above shows a western and northern shift. Though the proximal populations that contributed to this shift are somewhat different, overall the distal ancient components (e.g., “Neolithic”) return to frequencies that are closer to Iron Age Latium than the Roman Imperial phase. How did this happen?

Ancient DNA is a great window into the past, but it needs to be synthesized with an understanding of historical and anthropological processes. The Rome of the 400s was still a massive city, only marginally off its imperial peak in terms of population. But the Rome of 600 A.D. was a city filled with emptiness. What happened? A combination of the wars of the 6th-century, which are recorded to have depopulated much of Italy, and the overall decentering of Rome from the Mediterranean system after the ending of the Western Empire, probably resulted in the inevitable contraction of the Eternal City.

Of course, Rome grew again over the centuries. But the new Romans were not the same Romans as those of the Roman Empire, who left few descendants. In addition to far off cosmopolitans, the bulk of the population was probably derived from northern Lazio and southern Tuscany. Rural people whose genetic makeup resembled the Iron Age Italians from whom they descended.

This answers the question that people have been asking for decades: are modern Romans descended from the people of Republican Rome or Greeks and Syrians who transformed themselves into Romans? The answer is neither. Modern Romans descend from Italian peasants, who were less impacted by the predations of the Goths and Byzantines, and had higher fertility than urban dwellers even in peaceful times.

Which brings me to a second paper in the same issue of Science, The Church, intensive kinship, and global psychological variation:

There is substantial variation in psychological attributes across cultures. Schulz et al. examined whether the spread of Catholicism in Europe generated much of this variation (see the Perspective by Gelfand). In particular, they focus on how the Church broke down extended kin-based institutions and encouraged a nuclear family structure. To do this, the authors developed measures of historical Church exposure and kin-based institutions across populations. These measures accounted for individual differences in 20 psychological outcomes collected in prior studies.

The results are not that surprising, though the statistical rigor of the paper is impressive. I first encountered the idea about the instrumental role of the Western Church in imposing a new family order in Western Europe in Adam Bellow’s In Praise of Nepotism (others may have heard about this via HBD Chick). Bellow offers a very simple explanation: the early Roman Catholic Church used its ideological power to prevent the emergence of powerful lineage groups. More concretely, limiting marriage prospects of elite lineages increased the probability that properties of wealthy families would be given to the Church as a gift.

In some ways, this paper has nothing to do with the first. But note that the period when the Western Church began to transform the familial structure of Western Europe is at the end of the Roman Empire. Between the 6th and 9th centuries the Roman Church was a particularly cosmopolitan institution in a rapidly barbarizing Western Europe. In the 7th and early 8th century, there were a series of ethnically Syrian Popes, to give one example. As the post-Roman world in the West began to devolve into localism, the Western Church remained international. Global.

Consider then this Late Roman institution, the Western Church, a locus of urbane cosmopolitanism reflecting the civilian values of the ancient Roman aristocracy, surrounded by a rising tide of unlettered barbarism in the form of marginally Christianized Lombards and their ilk. This cultural tension during these centuries of Late Antiquity may lay at the root of the ideological program promoted by the Western Church against the ascendent barbarian elites which had inherited the mantle of Rome.

Finally, a map within this paper showing the role of kinship in modern societies illustrates a striking pattern:

In Victor Lieberman’s Strange Parallels he asserts that Southeast Asia, like Europe, is part of a “protected zone” against the predations of the steppe. As such, it retained stability and continuity which allowed for the emergence of modern nation-states. Notice that Theravada Southeast Asia has a low kinship index, just like Europe (Vietnam, like China, has a high kinship index probably because of Confucianism’s focus on family as the atomic unit of society). Japan, also part of the “protected zone”, has a low kinship index.

It strikes me that exploring the role of institutions and historical contingency in these regions in decreasing the importance of familialism might be something that needs to be done. With that being said, the fact that the Western Church inherited Greco-Roman aversion to polygamy and innovated its own aversion to consanguinity resulted in a very unique familial configuration in Western Europe. Monogamous. Deemphasizing the extended kinship group.

We live in a time when some people would assert that “Western civilization” is a racist term. But it seems to me that these tendencies within Western civilization are highly correlated with flourishing and innovative societies.

Making Sense of Roman History: A Reading List

Inspired by Tanner Greer, I’ve decided to put together a list of books that I think will useful to understanding the Romans from the perspective of a non-specialist without a background in Latin, or Classics more broadly (I am in this category obviously).

First, I’m a big fan of Michael Grant’s History of Rome. Grant was a historian who wrote a great many books for the popular audience, and his History of Rome is a comprehensive survey. I’ve read it multiple times. Mary Beard’s SPQR: A History of Ancient Rome is a more contemporary take which covers a similar period. But I’m not sure it’s as useful if you have less background than Grant’s more traditional sequence.

Robin Lane Fox’s The Classical World: From Homer to Hadrian covers a lot more than Rome, but what it does cover that is Greek is essential to understanding Rome.

Adrian Goldsworthy’s The Fall of Carthage: The Punic Wars 265-146 BC is a good read on a classic topic. Goldsworthy is a military historian, and it shows. To be frank I haven’t read many treatments of the republican period since so much of it is back-loaded to the decades before the principate. But Goldsworthy’s Caesar: Life of a Colossus illuminates this critical juncture in Roman history well enough.

There are so many nearly novel-like treatments of figures from the Second Triumvirate and the Julio-Claudians that I’m not going with anything conventional: try Agrippina: Sex, Power, and Politics in the Early Empire. Colin Wells’ The Roman Empire focuses on the imperial apogee and the early years of the 3rd-century troubles. It’s a bit pedestrian but has interesting quantitative data like the decline in the proportion of soldiers of Italian origin over the centuries. If you’ve read the survey above then you know why Gwyn Morgan’s 69 A.D.: Year of Four Emperors is important to read.

I think biography is a pretty good way to get a sense of particular periods. With that in mind, Frank McLynn’s Marcus Aurelius: A Life and David Potter’s Constantine the Emperor are useful if a bit plodding and overmuch for the casual student.

The Fall of Rome: And the End of Civilization, The Fate of Rome: Climate, Disease, and the End of an Empire, and The Fall of the Roman Empire: A New History of Rome and the Barbarians are all critical contemporary analyses of the end the Roman polity. Written from an archaeological, environmental scientific, and narrative historical angles, they give different viewpoints on the same questions. These are all more or less responses to the sort of work written by Peter Brown a generation earlier, The Rise of Western Christendom: Triumph and Diversity, A.D. 200-1000, which argues against the idea of the fall. From a different perspective (the barbarian), The End of Empire: Attila the Hun & the Fall of Rome, though to be frank this book is as much about Aetius as it is about Attila.

Life and Leisure in Ancient Rome is one of the many books on the topic of “daily life” during this period and place. You should read at least one of these.

I’m not a humanist in Tanner’s league, so you won’t get poetry recommendations from me, but Aupelius’ The Golden Ass is the only complete surviving Latin novel. It’s rather weird. You surely know the list of eminences of the Latin poets, but Ovid’s Metamorphoses induced less labor than Virgil’s Aeneid. I recall thinking Virgil was a bit too “try hard.” Unlike The Fall of Rome: And the End of Civilization and History of Rome, both of which I’ve read more than half a dozen times front to back, with literature I usually read once, and don’t retain too much. I’m a Philistine!

Rome and China: Comparative Perspectives on Ancient World Empires and Rome and Jerusalem: The Clash of Ancient Civilizations are interesting comparative analyses. If you had to pick between the two, go with the first. But that’s because purely intellectual histories are not as interesting to me.

Historical fiction isn’t always accurate, but it really brings the dramatis personae alive. Colleen McCoullough’s First Man in Rome series is excellent, especially the first few novels. Everyone knows Robert Graves’ I, Claudius. But my teenage-self really enjoyed Allan Massie’s Let the Emperor Speak, about Augustus, and Tiberius: The Memoirs of the Emperor. Gore Vidal’s Julian: A Novel is well written and engaging, though a little light on history (not surprisingly there is a lot of editorializing by Vidal through Julian).

You have in some way read the works of Seutonius,Tacitus, and Livy because they are the foundation for so much of the narrative works written today. They are also the source material for fiction and dramatizations. If you want to “go back to the sources”, give Ammianus Marcellinus a try. He’s overlooked, and he’s excellent.

Rodney Stark wrote The Rise of Christianity: How the Obscure, Marginal Jesus Movement Became the Dominant Religious Force in the Western World in a Few Centuries back when he was a scholar and not a polemicist. I’m skeptical of some of his conclusions, but his thinking here is rigorous. It’s not the long scream that his last few books have been. Robin Lane Fox’s Pagans and Christians is complementary to The Rise of Christianity. Michelle Salzman’s The Making of a Christian Aristocracy: Social and Religious Change in the Western Roman Empire is worth a very deep read, as it synthesizes textual analysis with some quantitative work.

Some of the New Testament is interesting too. I especially think that the material attributed to St. Paul, a Roman citizen, is worth reading closely.

And finally, St. Augustine is worth a read. City of God is interminably long, but Confessions is more compact, and the beginning of a whole genre which eventually culminated in James Frey.

The material consequences of Rome’s decline


The plot at the top is from a Peter Turchin post, History Is Now a Quantitative Science. Peter has been on this for more than ten years now. I’ve long been broadly sympathetic, but of late it’s been nice to see his formal and data-intensive approach take hold and make some waves. Using raw data from a PNAS paper on the concentration of lead in Greenland ice caps one can illustrate the theory of secular cycles, as the western edge of the oikoumene went through periods of rise and fall. I don’t say specifically Rome because as Peter observes the first rise probably had more to do with Carthage than Rome, and the last recovery was particular mild probably because its focus was on the eastern Mediterranean, rather than the west.

As readers of this weblog know this lead data is not entirely new. I remember stumbling on it in The Fall of Rome: And the End of Civilization. It’s just more fine-grained and detailed than what came before. This sort of result definitively convinced me in a flash that the “fall of Rome” was neither fiction nor propaganda, but a true material event.

And yet the materiality is important. Like Song China, the Augustan and Antonine periods were characterized by a phase of intensive coordinated economic activity and productive output that one can’t deny. It’s right there in the material record. But from the perspective of a Christian or a Muslim, the collapse of the power of the Roman state coincided with the rise to power of the most important development in human history: the cultural dominance of singular religious visions.

The point being that when we say that “Rome fell,” it hides within it assumptions of value and importance. History is not fiction and can be understood in all its reality, but it is always critical to expose your assumptions and gain an understanding of the common ground shared between individuals whose viewpoints may differ.

 

The Roman, the Hun and the sun


I chose a fortuitous time to read Kyle Harper’s The Fate of Rome: Climate, Disease, and the End of an Empire. This is a great book, and a nice compliment to Bryan Ward-Perkins The Fall of Rome: And the End of Civilization. Where Ward-Perkins attempts to convince you that Rome did indeed fall, and that that fall mattered, Harper takes it as a given that you accept this position. Rather, he tries to show you in The Fate of Rome that a series of contingent and necessary causal factors set the Roman system up for its fall. The fall of Rome is not just an idea, but a material event that was given a strong push by material factors.

As the The Fate of Rome was published in the fall of 2017, so it was written well before recent work which highlights both the nature and role of steppe barbarians in triggering the changes which we dramatically term the “fall of Rome” and the “barbarian migrations.” A few months ago I wrote about a paper which reported that post-Hunnic people of the Balkans were genetically different from typical Europeans in that they exhibited some East Asian admixture. Harper does assume that the Huns were barbarians whose ultimate provenance was somewhere in the region of modern Mongolia, but emphasizes that their peregrinations transformed them.

As so it did. A new paper in Nature, 137 ancient human genomes from across the Eurasian steppes, nails the overall dynamics. As illustrated in the figure above the early steppe was dominated by peoples of a West Eurasian provenance, while the latter steppe shifted toward a more East Asian shifted population.

These early groups go by various names. But the Cimmerians, Scythians, and Sarmatians have origins on the Pontic steppe. Flourishing in the first millennium before Christ, I should precisely label them “Iranian,” but that might mislead readers a bit since some of these groups were never resident within Iran. The Scythians were a presence across a huge zone of Inner Asia and were a force in Eastern Europe, West Asia, South Asia, and in Eastern Asia. Likely emerging out of the Andronovo culture, genetically the results from the paper confirm early work that Scythians mixed with the local substrate where they went. In this way, they prefigure later steppe populations. Being a nomad was a lifestyle, the genetic correlates to some extent an accident.

In The Fate of Rome  the Huns have a role to play as a push for the migration of Goths into the Roman Empire, which eventually leads to their rebellion and a collapse in both the prestige and military manpower of the Roman state. The genetic evidence above and elsewhere is strongly indicative of the likelihood that the Huns were originally part of the Xiongnu confederacy. As they moved west they mixed with post-Scythian and other Iranian and Siberian elements, and presumably by the time they arrived on European frontier of Rome they had picked up some Germanic and proto-Slavic ancestry. In 137 ancient human genomes from across the Eurasian steppes the authors also report that the East Asian gene flow was somewhat “male-mediated” in the later steppe. Similarly, earlier work on proto-Iranian peoples in the Altai region is strongly suggestive of male-mediation in West Eurasian gene flow.

The obligate and exclusive Eurasian nomad lifestyle was one dominated by men, though as one can see the importance of Genghis Khan’s wives and daughters women maintained independence as well.

For whatever reason, full-blown nomadism only became a feature of the landscape north of what became China in the last few centuries before Christ. The mobile and militarized nomadic lifestyle that emerged in western Eurasia in the years around 1000 BC seem to have taken five centuries to penetrate the far eastern fringes. Until the crushing of the Dzhungar’s by the Manchus in the 18th century, 2,000 years later, the dynamic between nomad and settled was a defining feature of Chinese statecraft and political culture. And, it was also a major feature of nomad culture, because the wealthy Chinese state was an almost irresistible attraction to steppe elites as a source of plunder and tribute.

But human action is not the only relevant parameter in human history.  The Fate of Rome  is fundamentally a work of history, but it also takes ecology and evolution seriously. In fact, it foregrounds them. Kyle Harper makes the argument that the expansionary phase of the Roman Empire was not necessarily coincidental, or at least it was lucky indeed because there was a climatic optimum, similar to the one which preceded the demographic expansion of medieval Europe. In contrast, in the 6th century, the world went through some of the coldest years in the Holocene because of a combination of fluctuations in solar radiation and volcanic explosions. I assume that the likelihood of the latter is Poisson distributed, so the combination of decreased radiation and several successive volcanic events can be chalked up to randomness. But its consequences were not random at all.

The climatic changes can have demographic and social consequences obviously. Desperate armed pastoralists can overwhelm states, and change the course of history, just as peasants can rebel from taxes and subordination. And, pastoralists can also bring Yerisina pestis, the plague. Climate is an abiotic pressure which is to some extent an exogeneous shock which occurs randomly, and does not react to human feedbac k.* Disease though is a biotic pressure, and though it may relate to abiotic forces, human interaction and agency matter quite a bit.

The Fate of Rome clearly hinges on abiotic factors as initial drivers: a good harvest is good for the state. But the biotic factors, disease, are partly under the control of the state. The Romans did not have germ theory, and were under constant stress due to the high pathogen load, especially of the cities. Harper presents the evidence of high mortality within Roman society well. Because of the endemic ubiquity of disease even elites were impacted by it. But Rome was not just affected by endemic ailments, it was subject to pandemics and plagues. Three loom large in  The Fate of Rome:

  • The Antonine Plague, which ended the expansionary phase of the High Empire in the middle to late 2nd century.
  • The Plague of Cyprian of the middle 3rd century which ushered in a period of state collapse.
  • And finally, the Justinian Plague which marked the end of Late Antiquity and the beginning of the “Dark Ages.”

One of the major insights that Kyle Harper reiterates is that these plagues, these pandemics, are a feature/bug of the Roman imperial system. They are not just the consequence of simply settled agricultural society. As described in books such as Pandora’s Seed, agriculture and settled society transformed the lifestyles of human groups, and many diseases which were rare in hunter-gatherer populations probably became common among farmers. But The Fate of Rome the author argues that pandemics were a novel outcome of complex imperial state-systems with long-distance trade-networks. Small-scale pre-state Neolithic chiefdoms did not have the scale and interconnections to foster plague.

Mass pandemics of smallpox, plague, and influenza are then aspects of civilized life, not, settled agricultural life. This puts the argument of Charles C. Mann in 1493 into greater focus. It wasn’t just more extensive and intensive agriculture in the Old World which left Amerindians vulnerable, it was also that the Old World had thrown up several massive imperial systems which had incubated pandemic producing pathogens (smallpox and influenza epidemics were a major issue in New World societies). These were unleashed at once upon New World societies.

It also suggests to us why adaptation seems to be occurring in the last few thousand years. Bouts of plague which persisted for generations may have driven immunological responses.

Kyle Harper also seems to agree with the general thesis in The Fall of Rome that this period in European civilization was in some ways proto-modern, with economic specialization resulting in a modicum of affluence in ways unimaginable in times before, or after. Trade and some level of mass production allowed British peasants to eat off tableware that was standardized, and not homemade. In contrast after Britain’s post-Roman regression a more local economy had to step in. The most curious fact from The Fall of Rome is that pollution in British ponds did not attain Roman levels until the early modern period, with the rise of industrialization. Again and again  The Fate of Rome emphasizes that social and economic complexity achieved in the Roman Empire was not attained in Europe again to the same scale as the early modern period.

Roman wealth was fundamentally due to the returns on scale and specialization that are the hallmark of Smithian growth. Though the Romans did invent a few things, Roman prosperity was not fundamentally driven by innovation. Rather, the Roman peace was a framework for trade and exchange that took advantage of abiotic clement conditions (the Roman climatic optimum highlighted in The Fate of Rome).

But this political system had biotic costs, as well as being subject to biotic shocks. Though Romans may have been wealthier than their Iron Age predecessors in things, and also wealthier than their early medieval successors, they were also a smaller people. Using isotope data Harper suggests that this is not due to Malthusian immiseration as the imperial population pushed up against food supply. Apparently Romans did not subsist on gruel alone, but ate a fair amount of meat, especially pork. Rather it was the high pathogen load enabled by the advancement of Roman urban life and its scale. Rome was a world of intense morbidity.

Unlike physical/abiotic forces biological/biotic pressures on human existence are adaptive. Moderns know this with the rise of antibiotic resistance, it’s the eternal race. The Romans were not aware of the consequences of their means of prosperity, and were not ready for the exogenous shocks of climate and disease which were to perturb their state system.

But The Fate of Rome is not just a story of exogenous factors, climate and disease. Rather, Harper puts into stark relief the variables which might push an empire over the edge, or eat into its seed corn of human capital. That does not negate the fact that endogenous variables matter. The Roman elite of the early centuries exhibited some level of asabiyyah, social cohesion. The Empire was fundamentally not a strong state in comparison to modern ones. It was a thin skein of cities and fortifications binding together an overwhelmingly rural population of villages. Its achievement of peace and prosperity was bound up in an ideology and identity focused project which bound together an elite (or bound together elites).

The origins of this elite were not always arbitrary. Though the Empire was famously cosmopolitan, The Fate of Rome crystallizes something that anyone who had sat back and thought about could see: certain groups bound the imperial state together as a ruling caste. Harper observes that between the reign of Claudius and Phocas, from 268 to 602, 75% of the Emperors were of Illyrian/Balkan stock. That is, 75% of the Emperors were drawn from 2% of the Roman Empire’s territory. The exception being the Theodosian dynasty, which was of Iberian origin and jumped into the breach after the defeat of Valens at Battle of Adrianople.

This is a fascinating fact in and of itself. Harper points out that these Emperors from the Danube frontier did not enrich their own region to the detriment of others. They were ideological heirs of the earlier Roman project, and their identity was as Romans first, Illyrians and Thracians of Latin stock second (or third, after Christianization). But they brought particular skills of administration and an overall martial attitude which served to lead the Empire through a period of greater stress than it had been subject to during the earlier climatic optimum.

The Fate of Rome does not plumb the depths of ideological and social change but emphasizes their interaction with biotic and abiotic factors. Harper observes that public temple building decreases sharply after the Cyprian plague. Why? Perhaps there was a loss of faith in the old religious institutions. Though popular paganism remained dominant, new elite religious ideologies such as the cult of the Invincible Sun and later Christianity came out of the shadows during this period.

These cultural and political aspects remain bit players and mostly offstage in The Fate of Rome. If you are interested in political narrative, then something like Peter Heather’s The Fall of the Roman Empire may be more to your taste. If culture, then Mary Beard’s SPQRBut ultimately social, political, economic, biological, and climatological factors are critical and interconnected. The rise of plague is hard to understand outside of the context of trade, which was enabled by political power and unity. Ecological factors may have driven Yerisina pestis out of its Central Eurasian reservoir, and those ecological factors may have been triggered by climatic variables.

The fall of Rome is a huge topic. I’m just glad that we’re beyond the revision of the previous generation which denied that it happened in the first place. The reason that it occurred is probably contingent in the details, though inevitable over the long-term. All things must end, even the Roman peace.

* This is not totally true, but over the time-scales we’re talking about probably mostly true.

The genetics of the Lombard folk migration


There are many debates about the period after the fall of the Western Roman Empire in the late 5th century. For example, did it “fall” in the first place? I believe that the concomitant p0litical, social, and economic changes do warrant that word. But another question concerns the “barbarians,” who were mostly German peoples (there are some exceptions, such as the Iranian Alans and the Huns, whose specific provenance is unclear). Were they ethnically and politically coherent? Were they even peoples?

The extreme stylized positions might be outlined as follows:

– The barbarians who filled the political vacuum after the collapse of the late Roman state were coherent preexistent ethnic and political entities of German origin who migrated en masse and engaged in a folk wandering.

– Though their original provenance may have been in bands of German warriors from specific tribes, but the time they appear on the stage of history as we understand it, the barbarians were in fact a motley crew of opportunists of various origins, who adhered to a “barbarian” identity which was created de novo with the collapse of Rome. They were made by the collapse, they did not cause the collapse.

In the late 1990s, Norman Davies in The Isles presents an argument closer to the latter for the British Isles. That is, the Anglo-Saxon character of Britain was to a large effect a function of elite emulation and diffusion of a Germanic culture introduced by what was operationally a late Roman mercenary class. Davies alludes to texts which indicate a substantial native British population in Anglo-Saxon England centuries after the fall of Celtic kingdoms. This is in contrast to the apocalyptic vision of British monk Gildas, who depicts his Brythonic people fleeing before pagan Saxons and being driven into the sea. And, I have alluded to the possibility that the West Saxon monarchy, which later came to the center of English history during the Viking incursion, was in fact in origin Romano-British, rather than German (the early kings have Celtic names).

And yet England was always the most difficult case for cultural diffusion, because to a great extent Roman-British society did collapse. Both the British Celtic language and Christianity seem to have faded from the landscape, so the that the latter had to be reintroduced by Irish and continental European missionaries. Today, the genetics is more definitive, and it seems a substantial German migration did impact what became England, especially the east, what was the Saxon Shore. Though the majority of the ancestry of the people of England today seems to derive from people who were already resident in Britain in 400 A.D., a substantial enough minority seems to have greater affinities to people who were living in the stretch of land between the Netherlands and Denmark.

The case for mass migration on the continent of Europe (with the exception of much of the Balkans) is more difficult to make in a cut & dried fashion because the basic outlines of Romanness were much more intact in the centuries after the fall than in Britain. Though France and Lombardy may have names which derive from German tribes, there is not much that is German about these regions today, and frankly, even at the height of the barbarian rule when conquest and migration were fresh, the non-Roman overlay was likely a thin elite layer. Outside of Britan and the Balkans, the languages of the Roman Empire and the Christian religion maintained their dominance even after the fall of the Roman political order, a transformation of social norms, and the collapse of the economy.

And yet this does not deny the possibility of migration of peoples into this order. In Empires and Barbarians: The Fall of Rome and the Birth of Europe the historian Peter Heather argues that we must not neglect the likelihood that to some extent the arrival of the Germans was one of “folk wanderings.” That the identity of the Franks, Goths, and Lombards, did not emerge ad hoc and de novo through the accrual of military men around a tiny nucleus of German warlords and their retainers. That women and children were also part of the movement into the Roman Empire. Heather, in fact, depicts the Gothic arrival as one of destitute refugees fleeing the famine and chaos outside of the Pax Romana, and their subsequent militarization and rebellion as one forced upon them by the exigencies of their situation.

A new preprint on bioRxiv, Understanding 6th-Century Barbarian Social Organization and Migration through Paleogenomics, clarify these arguments in the case of the Lombards, who conquered Italy in the 6th century. The abstract:

Despite centuries of research, much about the barbarian migrations that took place between the fourth and sixth centuries in Europe remains hotly debated. To better understand this key era that marks the dawn of modern European societies, we obtained ancient genomic DNA from 63 samples from two cemeteries (from Hungary and Northern Italy) that have been previously associated with the Longobards, a barbarian people that ruled large parts of Italy for over 200 years after invading from Pannonia in 568 CE. Our dense cemetery-based sampling revealed that each cemetery was primarily organized around one large pedigree, suggesting that biological relationships played an important role in these early Medieval societies. Moreover, we identified genetic structure in each cemetery involving at least two groups with different ancestry that were very distinct in terms of their funerary customs. Finally, our data was consistent with the proposed long-distance migration from Pannonia to Northern Italy.

The preprint has genetic and isotopic results from two graveyards associated with elite Lombards of the 6th century. The one in late antique Pannonia would be in modern Hungary. The one in modern Italy is near Turin. The late 6th century was a time of tumult in the Roman Empire, as both Italy and the Balkans were subject to massive turnovers of the ethnic and political orders. The movement into Italy from the northeast was a typical one, prefigured by the Goths and other Germans before the Lombards.

From what I know, as far as German barbarians went, the Lombards were rather “raw” and non-Roman (in contrast, some tribes, such as the Goths and Franks, had had relationships with the Roman Empire for generations before they decided to take it over). Though they were nominally Christianized, and elite Lombards persisted in practicing pagan rituals in Italy down to the 8th century, over 100 years after their conquest of the peninsula.

The authors used a lot of “best of breed” methods with their large data set, but the ADMIXTURE plot really illustrates the result fine enough. The blue is associated with Northwest European ancestry (British and white Utah samples), red with Italian ancestry (Tuscan), and green(ish) with Iberian (Spanish mostly). The very light blue is 1K Genomes Finnish. Panel B is the graveyard in modern Hungary, and panel C is the one from northern Italy.

There is a strong correlation in the graves with those being of Northern European ancestry, and having high status via grave goods. The individuals also exhibited some segregation in the graves. Northern European ancestry and Southern European ancestry individuals were clustered together. The Pannonian individuals, whether Northern or Southern European, don’t seem to resemble ancient or modern Hungarians. The isotope analysis indicates that many of the individuals were highly mobile.

Finally, the data was robust enough to do a pedigree analysis. It looks like a lot of these individuals are related. If you look at the plots you can see groups with the label “Kindred.”

There is so much detail in the results that I won’t recapitulate. Just read the preprint and make sure to check out the supplementary text. What I will say is this.

  1. The Lombard migration seems to have been a migration of people of Northwest European heritage into Southern Europe.
  2. The migration occurred during the lifetime of some individuals. These were highly mobile individuals.
  3. There were associated groups with the Lombards, who were genetically distinct, and likely of lower status. Their Southern European character is also distinct from the native population of Pannonia in the case of panel A.
  4. The Lombards themselves had Northern European ancestry which was somewhat heterogenous (probably different tribes and ethnicities). The shift away from Finnish ancestry probably indicates sampling more from western and opposed to central Europe.
  5. Admixture with the local populations and other post-Roman groups began early on.

The ethnocultural distinctiveness of the Lombards is clear from the textual evidence. The genetic data here confirm that in totality. But, The Geography of Recent Ancestry Across Europe, also highlighted a lot of deep population structure within modern Italy, and could not discern much impact of barbarian migration outside of the Balkans across their data set. Why?

It is rather clear that there were population declines across the West Roman Empire in the years after the Gothic Wars. If you read the textual evidence you imagine some sort of catastrophe going on. In human terms it was catastrophic. On the scale of economics, it was catastrophic. But in terms of population genetics, the long-term impact was not that extreme. The local population structure was not much altered because the Roman population base was so high that even a large decline did not induce bottleneck effects, and the German elite was also small enough it did not much perturb the underlying structure which had roots back to the period before the Roman Empire. Even in the first generations of Lombards in Italy, which is the Collego data set reflects, there was intermarriage between German people and others.

The demographic impact of the German migrations was huge on culture, politics, and economics. But it was not huge on population genetics.

Disruptive ages happen…and they happen fast

A friend of mine was pointing out that there is something of an anti-civilizational polemic in Against the Grain: A Deep History of the Earliest States. It’s the same sort of impulse which also asserts that “Rome never fell it evolved” and that the “Dark Ages” is a myth. I pretty much agree with Scott Alexander’s take. The datum that pollution due to lead did not match that of Classical Antiquity until the early modern period is one I remember as a searing one from The Fall of Rome: And the End of Civilization. You can’t really argue with that.

After reading The Fall of Rome I had a period when I read a lot of stuff on late antiquity. For example Peter Brown’s The Rise of Western Christendom: Triumph and Diversity, A.D. 200-1000. Brown is a serious scholar, and I’ve read several more of his books. But, I do think it shares something with earlier scholarship, and some of the more polemic recent screeds of Rodney Stark (see How the West Won), and that is that Christianity is viewed as a good in and of itself.

That is, if there is one thing that can be said for the period after the fall of Rome, it is that Christianity transcended its Mediterranean focus, and became a truly international religion, and a light unto the nations. If you believe that Christianity is true, then details about population collapse and a recession of cultural productivity matter a lot less than otherwise.

I think the economic historical evidence on the balance does lead to the conclusion that the Roman Empire achieved an optimum of economic development during the Antonine period of the 2nd century A.D. through classical efficiencies on the margin (e.g., specialization through trade, bringing all of the land into production, etc.). These levels were not again reached until after 1000 A.D. in Europe, though comparisons are not entirely apt because innovations such as the moldboard plow and windmills allowed for increases in genuine economic productivity.

The bigger question that looms in the background though is would it have been better to be a median Roman citizen or a median subject of a Dark Age warlord? I don’t have a strong opinion on this, especially when it comes to the ability to consume above subsistence.  It seems likely that the far worst treatment of slaves in places like Sicily than anything serfs were subject to (though serfdom only truly came into its own during the end of the Dark Ages) should be weighed in the calculus, but the Roman peace was also a genuine peace. The petty conflicts persistent at a local level in the Dark Ages may have made the life of a typical peasant less secure than for Roman citizens.

Rather constant reports of subjects and citizens fleeing from strong political units, or more “advanced” nations (e.g., the early American frontier), tell us something real. People valued freedom. But not everyone fled, so we’re probably seeing a bias in terms of who attempted to escape the shackles of civilization (e.g., young able-bodied single men, in particular, loom large in these reports, and I think there’s a reason for that).

Roman cultural history has almost no demographic imprint


Several friends have asked that I weigh in the recent dust-up between Nassim Nicholas Taleb and Mary Beard. I haven’t for a few reasons. First, I can’t really be bothered to go incognito and see every detail of Taleb’s argument, as he has me blocked on Twitter (he called me a fucking idiot or something at some point). Second, the passion around this topic has little to do with genetics or ancient history from what I can see, two topics which I am actually interested in. Rather, it’s more about contemporary geopolitics. This is interesting too, and I have opinions on that, but I try really hard to keep history and politics in separate silos unless I am explicit about the connections and relevance. That’s because I don’t see classical history as simply something instrumentally important for modern times, but interesting in and of itself (the same goes for population genetics).

And for what it’s worth, Mary Beard says the same in her conclusion to SPQR. The ancients were ancients. Let them be what they were.

That being said, as someone with knowledge sets in ancient history and historical population genetics, I will make a few statements and let others interpret them however they wish (to be frank, I’m not going to cede ground to any of the experts I’ve seen who have spoken on the intersection of these two knowledge sets, so I figured it was time to put something somewhere beside Twitter).

* The prior probability that a Roman officer of the period in Britain would have visible black African ancestry (as seems clear by the cartoon, though no one has asked the cartoonists what their intent was) probability seems rather low. But it is non-zero, because a small minority of Roman subjects and citizens would have been defined as black by their physical appearance if they were alive today (they are mentioned passingly in the literature and texts from the period). Including in Britain.

* The probability conditional that he was based on an officer in Britain who was a native of Tidis is low, but higher. Several historians have pointed out in defense of the cartoon’s plausibility that there were many North Africans in Roman service, as well as prominent North Africans in Roman history (to name three of note, Septimius Severus, Tertullian, and St. Augustine). Whole tribes of what we’d today term Berbers enrolled in the Roman military a federates.

There are several separate issues to note. First, of the many North African genotypes I’ve seen detectable Sub-Saharan ancestry is found in almost all of them. But, many (most?) North Africans do not look visibly of Sub-Saharan African ancestry (see list of heads of states of Algeria). Second, both historical and genetic evidence indicates that this admixture from Sub-Saharan Africa is overwhelmingly (though not exclusively) from the period after Islam and the rise of a much bigger trans-Saharan trade (see Genomic Ancestry of North Africans Supports Back-to-Africa Migrations). Modern North Africa does have a large population today of people who are black or of obvious part-black ancestry, but this is due to the slave trade under Islam, and not antiquity.

* As evidence of the lack of non-European ancestry the paper The fine-scale genetic structure of the British population has been submitted. This is a great paper with best-of-breed methods and a massive data set of native English, with regional data. How do we resolve textual and archaeological evidence of people born outside of Britain during the Roman period in Britain with their lack of long-term genetic footprint among native modern Britains?

These sorts of questions need to be integrated in a broader context of the demography and genetics of antiquity that we have. On the whole looking at papers on modern and ancient DNA I am surprised by the lack of perturbation on the genetic structure attributable to the Roman period across Western Eurasia. I will offer two likely reasons that are related.

First, Classical civilization was an urban one, and the textual evidence we have is going to be highly skewed culturally in terms of our perception. The Roman world was predominantly written in cultured Latin and Greek (from what I have read the early translations of the Bible are indicative of a more pedestrian background of Christians due to the class markers of their lexical choices and idioms). But it was not necessarily spoken in cultured Latin and Greek across vast swaths of its territory. Even in St. Augustine’s time Punic was still spoken in the North African countryside, while the persistence and resurgence of Basque and Berber, and perhaps Brythonic Celtic in Britain, attest to vast reservoirs of people who were under the Roman peace, but not of it (also, the persistence of Albanian from a native Illyrian substrate). Because of the resources historians have on hand, text, there is going to be a major lacunae in our understanding and perception of the past. We hear the urban elites speaking to us. Not the rural majority.

Second, Classical civilization was an urban one, and this might have a major impact on the demographic consequences of migration. At any given size the effective breeding population is smaller than the census population, and the breeding population may not be representative of the overall population in terms of their genetic character. More specifically, it seems highly possible that the cosmopolitan urban Roman cities were massive demographic sinks. Rome before the Gothic Wars was a very populous city, not too far on the path of decline from its early imperial peak. But by the year 600 it had decreased its population to the point that vast swaths of the city were abandoned. Where did these people go? No doubt some of the elites scattered. Cassiodorus simply moved when barbarism came to his front step. But this was less possible for the urban proletariat. There is strong evidence that slaves in the ancient world were not replacing themselves reproductively due to brutality under which they lived. Some of the same was likely true of the urban proletariat.

* There is a difference between the inheritance pattern of culture and genes. In The Geography of Recent Genetic Ancestry across Europe this passage has always stuck out for me: “There is relatively little common ancestry shared between the Italian peninsula and other locations, and what there is seems to derive mostly from longer ago than 2,500 ya…The rate of genetic common ancestry between pairs of Italian individuals seems to have been fairly constant for the past 2,500 years, which combined with significant structure within Italy suggests a constant exchange of migrants between coherent subpopulations.”

The straightforward conclusion from this is that the Latinization of the Italian tribes and Magna Graecia occurred with no great demographic transformation. Modern Italy has within it the ghost of tribes long gone. This is notable because if you read the historical records of the Roman period you see evidence of trade, transport, and migration. But the genetic data would not lead you to this conclusion outside of Sicily and a few parts of Southern Italy.*

Above I have presented my reasoning for why this might be. But I think what it tells us that genetic data can informs us when there is a demographic turnover, and therefore a cultural turnover, but it will miss cultural turnovers which don’t have demographic impacts. These are many. To give a few examples, the rise of Islam in South Asia and Southeast Asia, the Latinization of the Western Mediterranean, the de-Latinization of Britain after the withdrawal of Roman legion and before the mass arrival of Saxons, and arrival of Buddhism in East Asia. All these are massive historical and cultural events, but they would not be visible in the genetic record.

If you want to learn about Roman history there are many books you could read. But I do recommend you try Bryan Ward-Perkins’ The Fall of Rome: And the End of Civilization. It’s a nice materialist take, and I think it gets to the underlying dynamics of institutional fragility of ancient civilization which was so easily wiped away by barbarism.

Addendum: The migration of the Slavs, Anglo-Saxons, and the Islamic Empires, all seem to differ from antiquity in having a major demographic impact. Why? In the case of massive institutional collapse, as in the first two cases, very old dynamics of inter-group competition arise, and famine probably does the rest of the trick. For Islam, it was a genuinely cosmopolitan civilization, with a more complex gradation between free and slave than in antiquity. Though it was quite brutal, African and Turkish slaves became free, and their genetic impact can be seen throughout the Islamic world.

* Like Spain, a substantial proportion of the Sicilian gene flow exchange is almost certainly due to the Islamic period. There are segments of North African and Sub-Saharan ancestry in Sicilians, albeit to a smaller extent than in Spain (in keeping with the shorter time period as part of the Islamic world).