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May 24, 2018

The souls of peoples gone

Filed under: Demographics,Pots not Peoples,Roman History,rome — Razib Khan @ 11:14 pm



Stonehenge was first erected around 3100 BC, though the timber was only replaced with stone in 2600 BC. The great monument was a product of the Late Neolithic in Britain. Ancient DNA today tells us that these people were distantly related to the modern Sardinians, and derive from a wave of farmers that radiated out of Anatolia across much of Europe.

About a century after the stone form of Stonehenge was erected, prehistoric Britain was culturally and genetically transformed. In the space of a few centuries after 2500 BC there was nearly a ~90% genetic turnover, and a new people more closely related to Northern Europeans in Germany and further east became ascendant. The majority of the ancestry in Britain today probably derives from this migration period.

And yet the new people continued to utilize Stonehenge for over 1,000 years. Clearly, they co-opted a monument erected by their predecessors and maintained its significance across an enormous cultural disruption.

This is on my mind because on the episode of The Insight recorded with Patrick Wyman (it will probably drop in June) we talked extensively about Roman demography. And one of the peculiarities of 2013’s The Geography of Recent Genetic Ancestry across Europe is that Italy has a lot of deep population structure. From the paper:

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. An exception is that Italy and the neighboring Balkan populations share small but significant numbers of common ancestors in the last 1,500 years, as seen in Figures S16 and S17. 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 implication here is that there’s population structure deeper than the Roman period. When I first saw these results I was surprised. Looking at genome-wide data I was pretty sure that most of the modern Italian population dated to the Roman Republican period, but I was not expecting provincial level substructure. It was like telling me that the Samnites and Umbrians were still with us!

But what about the great cosmopolitan cities of Neopolis, Rome, and Ravenna? Some commenters on this blog routinely get frustrated when I dismiss the textual and epigraphic evidence of massive migration into the Italian peninsula during the height of the Roman Empire. Actually, I believe that this migration occurred. I just do not believe it was particularly impactful genetically today. Though my general outlook on this issue goes back over ten years (in part thanks to the suggestion of Greg Cochran), I believe the issue here is that cities are such incredible demographic sinks.

Roman urban cosmopolitanism was parasitic on migration. Demographically it was never self-sustaining. In fact, as Patrick points out urban areas probably did not see sustained above replacement reproduction anywhere in the world before about 1900, with the emergence of germ theory and massive public sanitation works, especially in the United States. This is evident in books as diverse as Kyle Harper’s The Fate of Rome and The Rise and Fall of American Growth.

So did Roman urban civilization leave nothing to posterity? On the contrary. Like much of Rodney Stark’s work in the last twenty years Cities of God is needlessly polemical and oftentimes unscholarly*, it gets at the reality that Christianity was fundamentally an urban cult. It was brought to Italy by people from the Eastern Mediterranean, Jews and Greeks. In its early period it was dominated by urban cosmopolitans. Some of the sermons in urban churches even castigated rural peasants  as pagan beasts of the field.

Christianity was an international religion with foreign origins, and like many elite cultural constructions of the pre-modern oikoumene its existed operationally as a social network across the various cities around which elites congregated. In some ways the vast sea of villages which filled in the landscape were untouched by many of the cultural innovations occurring in the cities. A Neolithic person might be confused by some aspects of Roman village life (in particular, access to standardized manufactured goods), but they would be totally flabbergasted by the city of Rome.

Over the 200 years between 400 AD and 600 AD the population of Rome probably went from ~500,000 to ~50,000. The decline of the Western Empire and the period of the Gothic Wars choked off the economic subsidies which could maintain the city’s population by drawing newcomers. And yet the Bishop of Rome, the Pope, remained in the city. If Patrick and I are correct then medieval Rome was repopulated by the descendants of peasants from Lazio, the hinterlands around the city.

Some scholars, albeit often from a partisan Protestant viewpoint, have suggested that the Western Christian Church of the early Middle Ages did not truly Christianize the peasantry. Whether this is true or not, it does seem to correct to say that deeply rooted popular Christianity took many centuries to become pervasive in rural areas. Despite their relative decline in the medieval period, both substantively and in terms of cultural prestige, cities remained remained the stalwart redoubts of Roman Christianity. They were the braintrust of European civilization, even if they were not demographically self-sustaining.

To a great extent the last ten years has seen a refutation of “pots not peoples.” It turns out that many of the archaeological transitions seen in the physical record correlate with demographic changes inferred from genetic changes. And yet we know from history that some peoples and social groups which were highly influential left far less of a demographic footprint. I suspect that the rise of cities and complex polities transformed the “pots not peoples” calculus significantly.

* Google the fact that about ten years ago Stark was dismissing reports that Americans were getting more secular as wishful thinking by biased liberal scholars. Who do you really think had a bias with hindsight?

May 19, 2018

The material consequences of Rome’s decline

Filed under: Roman History — Razib Khan @ 9:40 pm


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.

 

May 12, 2018

The Roman, the Hun and the sun

Filed under: Roman History — Razib Khan @ 8:23 pm


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 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, than 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.

March 13, 2018

The barbarian invasions, illuminated by genetics

Filed under: Huns,Roman History — Razib Khan @ 1:02 am

My own comprehension or understanding of the fall of Rome and the barbarian invasions probably began when I was about nine years old when I read a book about the various peoples who crashed the gates of civilization. First and foremost in the various descriptions were the Huns, a mysterious and fearsome race who in previous times had almost a talismanic role in the history of this period. Like the Mongols later on, they were more a force of nature that illustrated the hand of an angry God in the world than a people with their own agency.

But their identity was, and is, mysterious. Though contemporary descriptions seem to describe them as alien and repulsive in physiognomy, by the 19th century these antique descriptions were filtered through the racialist framework ascendent in the West of that period to cast them as foreign Asiatics. By the 20th century, a reaction set in and attempts to adduce the Huns’ possible connection to Central Asia seem to have diminished, though no one could deny the proposition either.

The fact that the ethnolinguistic affiliation of the Huns is mysterious to us should give a clue that they weren’t related to the standard Germanic or Iranian groups which operated on the fringes of the European Roman world. If the latter surprises you in the context of the European frontier of the Roman Empire, the Sarmatian tribes which pushed into Hungary and harried Rome defenses were related to groups like the Scythians, and branches eventually gave rise to the Alans (who ended up in the North African kingdom of the Vandals!) and Ossetians.* The German peoples have been observed by the Romans since the time of Cimbri invasions, and the later eruptions were easy to slot into that ethnographic framework.

In contrast, the Huns are mysterious precisely because they were a new cultural force. They seemed to be pure nomads like the Sarmatians, but not out of the Iranian steppe cultural milieu. Though they may have been a linguistic isolate, the most likely probability is that they spoke a Uralic (e.g., Hungarian) or Altaic language (e.g., Turkish). Like later steppe nomad hordes which burst out of Inner Asia into the Eurasian oikumene the genius of the Huns was in part organizational, as they accrued to their confederacy a motley of German and Iranian tribes. One standard narrative of the Gothic migrations is that their peregrinations were triggered by the movement of the Huns and their allies to their east and north.

An extreme social constructionist might assert that the term “Hun” simply brackets a new way to organize mobile barbarians beyond the Roman frontier. That they were not ethnically distinct. Though I don’t know anyone who holds to this extreme view, it’s not entirely impossible.

But now we have some genetic data. Population genomic analysis of elongated skulls reveals extensive female-biased immigration in Early Medieval Bavaria:

…we generated genomic data from 41 individuals dating mostly to the late 5th/early 6th century AD from present-day Bavaria in southern Germany, including 11 whole genomes (mean depth 5.56×). In addition we developed a capture array to sequence neutral regions spanning a total of 5 Mb and 486 functional polymorphic sites to high depth (mean 72×) in all individuals. Our data indicate that while men generally had ancestry that closely resembles modern northern and central Europeans, women exhibit a very high genetic heterogeneity; this includes signals of genetic ancestry ranging from western Europe to East Asia. Particularly striking are women with artificial skull deformations; the analysis of their collective genetic ancestry suggests an origin in southeastern Europe. In addition, functional variants indicate that they also differed in visible characteristics. This example of female-biased migration indicates that complex demographic processes during the Early Medieval period may have contributed in an unexpected way to shape the modern European genetic landscape. Examination of the panel of functional loci also revealed that many alleles associated with recent positive selection were already at modern-like frequencies in European populations ∼1,500 years ago.

The admixture plot is key. They have enough markers that intercontinental genetic differences should be discernible. The male and female symbols should be familiar to you, but they also classified the samples by the cranial deformation (a practice associated with the arrival of the Huns to Europe). Blue ~ no deformation, green ~ intermediate, and red ~ deformation.

You can see that the individuals with cranial deformation, who are females, are genetically very distinct from everyone else. And, in particular, the males who exhibit no deformation are pretty homogeneous. Both PCA and admixture suggest that the males resemble typical North-Central Europeans. That is, Bavarians. The women on the PCA plot are shifted toward Southeastern Europe, where anthropologically the deformations were much more common.

The authors analyzed the features of these women and determined that they were likely darker than the males in eye color. This is entirely reasonable in light of their more Southern European genetic character.

There are a few other random samples too. In the admixture plot, FN_2 is a Roman soldier from ~300 AD from the Munich area. About two centuries before the Bavarian samples. The authors note it is curious this individual seems to exhibit Spanish ancestry (IBS being the Spanish samples). And yet this ancestry did not impact the region. Anyone who reads a history of the Roman Empire and its fall and regression knows that the area of southern Germany, Austria, and Hungary south into the Balkans became highly barbarized. It seems likely that many Roman peasants died or fled back to the safety of the empire.

PR_10 is a Sarmatian from the southern Urals. The individual has more “Finnish” ancestry, but that’s not atypical for Russian samples. The South Asian ancestry is something I’d dismiss normally, but I think this might be shared Yamnaya heritage.

Finally, VIM_2, like AED_1108 (a Bavarian female with cranial deformation), has East Asian ancestry. This individual was sampled in Serbia, dates to the 6th century, and is presumably a Gepid, a relatively obscure German tribe.

The presence of East Asian ancestry in these individuals highlights the likely cosmopolitan character of the barbarian zone stretching from Hungary to Bulgaria. It should definitely increase our likelihood that the Huns spoke a Turkic language of some sort. By the time most Turkic peoples arrive on the scene in Western Eurasia, they’re highly admixed, but they invariably have some East Asian ancestry. I highly doubt that the Huns arrived in Europe with the Southern European ancestry, TSI (Tuscan). So that is probably admixture over the century and a half since they arrived that allows for this individual to be predominantly TSI (though the individual may also have been a later Oghuz migrant). The ancestry of the Huns should have been more like a mix of East Asian and Sarmatia. The latter sorts were the first “West Eurasians” they’d run acros unless they had originally come from further south in the Tarim basin.

In the decades before the Huns turned West, they harried the East Roman Empire, pushed its limes back toward the sea, and extorted tribue out of it. After the collapse of Attila’s Empire, they seem to have retreated back to the territories to the east where they could be self-supporting, as opposed to extorting protection money out of states more powerful than them. Because the Huns become less of a problem for the Roman Empire, we don’t hear much about them by the late 5th century. And yet that does not mean they disappeared. The human and biological ecology of this region seems to have been amenable to the intrusion of Eurasian nomads, by the end of the 6th century the Avar confederacy was dominant in the interior Balkans and toward southeastern Germany.

Though this paper is not exactly revolutionary, it confirms that individuals from a post-Hunnic cultural configuration are mostly indigenous, that some evidence of East Asian ancestry persist, it shows that many of the arguments about Late Antiquity as to the ethnological character of peoples will be resolved. Unlike prehistory, where we have no written records, this period has clear and distinct cultures which we have a grasp of. The empty spots on the map are smaller.

* Some captured Sarmatians were settled in Britain on the frontier looking north. There are conjectures that Sarmatian motifs may have influenced Arthurian legends.

February 21, 2018

The genetics of the Lombard folk migration

Filed under: barbarians,Germans,Lombards,Migration,Roman History,Romans — Razib Khan @ 9:13 am


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.

January 23, 2018

A commentary on the current year

Filed under: Roman History — Razib Khan @ 11:26 pm

November 12, 2017

Disruptive ages happen…and they happen fast

Filed under: Roman History — Razib Khan @ 9:58 pm

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).

August 15, 2017

Roman cultural history has almost no demographic imprint

Filed under: ancient Population Genetics,History,Mary Beard,Roman History — Razib Khan @ 9:48 am


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 due 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 hae 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 the North Africa 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 wars was a massive 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? I 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 exchanged 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).

January 2, 2013

When Rome fell civilization did decline

Filed under: Antiquity,History,Late Antiquity,Roman History — Razib Khan @ 9:37 pm

Before the Holidays I mentioned that I was rereading Bryan Ward-Perkins’ The Fall of Rome: And the End of Civilization. Why do I hold this book in such high esteem? Because of figures such as the one to the left. Granted, this chart is not from The Fall of Rome, but that book has an extensive bibliography which drew me to research on long term trends in pollutant concentrations. What you see illustrated are variations in the concentration of lead in ice cores from Greenland. Why is lead so important? Because it is a noxious byproduct in various primitive metallurgical processes. The basic thesis that Ward-Perkins fleshes out in great detail in The Fall of Rome is that the material basis of European life suffered a sharp regression after the collapse of the Roman Empire. In short the fall of Rome was the end of civilization, and what came after was coarser and more elementary in character. This may seem “common sense,” but it is actually a matter of some dispute and debate in the academy.

When discussing this issue there are two primary objections which always seem to come to the fore. First, after the de facto collapse of the West Roman imperium in the first half of the 5th century there were other societies of importance and grandness on the historical stage (see The Inheritance of Rome, When Baghdad Ruled the Muslim World, and China’s Cosmopolitan Empire). Far to the east of faded Rome Tang China’s glory waxed in the nadir of the European regression between 600 and 750. More well known to Westerners, the same period saw the apogee of Arab Islamic civilization. But the data above indicate that the industrial production of these two polities did not match that of the period around the peak of the Roman Empire. I refer here to period, because of course the Roman Empire flourished at the same time as Han China, and Sassanian Persia. The collapse of the 5th century was not a collapse of civilization as such, but of the western terminus of the oikoumene. And this decline was not compensated for by greater vigor in the Islamic center, or Chinese east.

Marcus Aurelius, 2nd century

A materialist perspective has the elegant attribute that it is less malleable in the hands of those with stylistic polish and the will and skill to engage in selective massaging of sources. I can assert plausibly I think that that the classical civilization which produced Thucydides, and later Polybius, Tacitus, and Ammianus Marcellinus, was superior in the fineness of its high culture than that in which Jordanes or the Venerable Bede flourished. But if an individual is clever, erudite, and set in their proposition, it will be impossible to definitively refute someone who holds that 8th century Anglo-Saxon England was no less cultured than 5th century Athens or 2nd century Rome. And if the exposition of the counter-intuitive position is placed in the hands of a cunning sophist, and the one who endorses common sense is plain and less learned, then the battle is already lost before it is begun. Terms like “superior” and “cultured” are slippery, and the whole enterprise of grading societies is held in bad odor in our age. A barrage of facts curated with intent to support a preposterous thesis can overwhelm simple sincerity. But the quantitative consequences of material production are not as contextualized or easily problematized. It is simply fact that proto-industrial production in the post-Roman world had regressed, and with it an array of material comforts and minor luxuries vanish from the record or become very rare. The dull can defeat the sly simply by pointing to the angle of the line on a chart.

A broader and more fundamental issue is that one must question how one judges the rise and fall of civilizations and society. From an orthodox Muslim or Christian perspective the collapse of Rome in the 5th century was an unfortunate incident, but ultimately secondary to the reality that the western half of the civilized world was to soon to be permeated by the presuppositions of their respective religious creeds. St. Augustine’s The City of God is only the most extended and thorough of many contemporaneous Christian apologetics which purport to explain the peculiarity of the collapse of the civilized (i.e., Roman) world just as the old pagan high traditions were finally superseded by Christianity. This is why I say that I find The Fall of Rome persuasive for partially normative considerations. Though I am willing to grant the superiority for various reasons of Christianity or Islam over the animistic primal religion of Republican Rome, or the Mystery Cults of the High Empire, I weight the extinction of industrial production of pottery and the reversion to localized barter economies as of greater consequence. Matter is more critical necessary precondition for civilization than mind. I doubt that Tacitus was anymore brilliant than Bede, but the former shone with more absolute greatness of the cultural capital which he could mine and leverage. The withering of the Christian church in the Balkans and England is a testament to the fact that higher religion themselves are preconditioned on a minimal level of social complexity and organization. It seems likely that by the 5th century Christianity succeeded in spite of the collapse of the West Roman Empire, not because of it. Rather than being a minor problem of history, the disturbance of the Roman order was a disaster for institutional Christianity, from which it only slowly recovered, still maintaining its original Roman outlines despite the Germanic interlude.

There are often debates as to whether fields like anthropology or history are humanities or social sciences. The truth is almost certainly both. In many ways I find archaeologists, particularly those of prehistory, theory-poor. Rather, what theory they attach to their wealth of material remains seems to be imbibed from the spirit of the times. Before World War II they were keen to illustrate the congruence of their material results with a migrationist narrative, while after World War II they rejected such models. But though archaeology can often tell us little directly in and of itself about the creators of a material culture, the flux of that material culture can tell us a great deal about aspects of that given society’s material workings. Technology is predicated on basic laws of nature, and those laws of nature produce constraints in the possibilities. Though it is possible in theory that Europeans between 500 and 1000 AD developed complex social systems which were also more ecologically friendly than those of antiquity (so as to generate less pollution in the material record), a more parsimonious explanation seems to me to be that in fact those societies were simpler, and that the order and institutions necessary for large scale proto-industrial production which had evolved organically from 1st millennium BC down to the Roman era had disappeared. This is simply not a matter of discourse, dialogue, debate, or contexualization. It is.

February 2, 2011

Empires and Barbarians: The Fall of Rome and the Birth of Europe

Link to review: Say it with me: Völkerwanderung

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