Nomads, cosmopolitan predators, and peasants, xenophobic producers

Ten years ago when I read Peter Heather’s Empires and Barbarians, its thesis that the migrations and conquests of the post-Roman period were at least in part folk wanderings, where men, women, and children swarmed into the collapsing Empire en masse, was somewhat edgy. Today Heather’s model has to a large extent been validated. The recent paper on the Lombard migration, the discovery that the Lombards were indeed by and large genetically coherent as a transplanted German tribe in Pannonia and later northern Italy, confirms the older views which Heather attempted to resurrect. Additionally, the Lombards also seem to have been defined by a dominant group of elite male lineages.

Why is this even surprising? Because to a great extent, the ethnic and tribal character of the post-Roman power transfer between Late Antique elites and the newcomers was diminished and dismissed for decades. I can still remember the moment in 2010 when I was browsing books on Late Antiquity at Foyles in London and opened a page on a monograph devoted to the society of the Vandal kingdom in North Africa. The author explained that though the Vandals were defined by a particular set of cultural codes and mores, they were to a great extent an ad hoc group of mercenaries and refugees, whose ethnic identity emerged de novo on the post-Roman landscape.

In the next few years, we will probably get Vandal DNA from North Africa. I predict that they will be notably German (though with admixture, especially as time progresses). Additionally, I predict most of the males will be haplogroup R1b or I1. But the Vandal kingdom was actually one where there was a secondary group of barbarians: the Alans. It was Regnum Vandalorum et Alanorum. I predict that Alan males will be R1a. In particular, R1a1a-z93.

But this post is not about the post-Roman world. Rather, it’s about the Inner Asian forest steppe. The sea of grass, stretching from the Altai to the Carpathians. A new paper in Science adds more samples to the story of the Srubna, Cimmerians, Scythians, and Sarmatians. Ancient genomes suggest the eastern Pontic-Caspian steppe as the source of western Iron Age nomads. The abstract is weirdly nonspecific, though accurate:

For millennia, the Pontic-Caspian steppe was a connector between the Eurasian steppe and Europe. In this scene, multidirectional and sequential movements of different populations may have occurred, including those of the Eurasian steppe nomads. We sequenced 35 genomes (low to medium coverage) of Bronze Age individuals (Srubnaya-Alakulskaya) and Iron Age nomads (Cimmerians, Scythians, and Sarmatians) that represent four distinct cultural entities corresponding to the chronological sequence of cultural complexes in the region. Our results suggest that, despite genetic links among these peoples, no group can be considered a direct ancestor of the subsequent group. The nomadic populations were heterogeneous and carried genetic affinities with populations from several other regions including the Far East and the southern Urals. We found evidence of a stable shared genetic signature, making the eastern Pontic-Caspian steppe a likely source of western nomadic groups.

The German groups which invaded the Western Roman Empire were agropastoralists. That is, they were slash and burn farmers who raised livestock. Though they were mobile, they were not nomads of the open steppe. Man for man the Germans of Late Antiquity had more skills applicable to the military life than the Roman peasant. This explains in part their representation in the Roman armed forces in large numbers starting in the 3rd century. But the people of the steppe, pure nomads, were even more fearsome. Ask the Goths about the Huns.

Whole German tribes, like the Cimbri, might coordinate for a singular migration for new territory, but for the exclusive pastoralist, their whole existence was migration. Groups such as the Goths and Vandals might settle down, and become primary producers again, but pure pastoralists probably required some natural level of predation and extortion upon settled peoples to obtain a lifestyle beyond marginal subsistence. Which is to say that some of the characterizations of Late Antique barbarians as ad hoc configurations might apply more to steppe hordes.

There has been enough work on these populations over the past few years to admit that various groups have different genetic characteristics, indicative of a somewhat delimited breeding population. But, invariably there are outliers here and there, and indications of periodic reversals of migration and interactions with populations from other parts of Eurasia.

Earlier I noted that Heather seems to have been correct that the barbarian invasions of the Roman Empire were events that involved the migration of women and children, as well as men. The steppe was probably a bit different. Here are the Y and mtDNA results for males from these data that are new to this paper:

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Why Bronze Age steppe people replaced the farmers they conquered

One of the major revisions in my own mind about the demographic and historical processes of the Holocene in relation to humans has been the reality that large and dense agglomerations of agriculturalists could be marginalized by later peoples, to the point of having a smaller genetic footprint in the future than anyone might have imagined. If you had asked me ten years ago I just wouldn’t have believed that the first farmers of Europe or South Asia wouldn’t account for the vast majority of the ancestry of the contemporary populations of the region. By “first farmers” I don’t even mean migrants. At that point, I had assumed a primarily Pleistocene indigenous hypothesis for the origin of Europeans and South Asians, with farming diffusing through a mixture of a few migrants along a demographic wave of advance.

That’s not what it looks like according to ancient DNA. In Northern Europe, it seems that around half or more of the ancestry is due to the incursions of a pastoralist steppe population during the Bronze Age. In Southern Europe and South Asia, the fraction is closer to 10-25%. But even in the latter case, the fraction of steppe ancestry is far higher than I had expected.

I had assumed that the steppe migrants would contribute 1-5% of the ancestry of Europeans and South Asians and that the spread of Indo-European languages was a matter of elite transmission and emulation. Think the Hungarians, for example, as an example of what had assumed.

So what explains what really happened?

During the Mongol conquest of Northern China Genghis Khan reputedly wanted to turn the land that had been the heart of the Middle Kingdom into pasture, first by exterminating the whole population. Part of the motive was to punish the Chinese for resisting his armies, and part of it was to increase his wealth. One of his advisors, Yelu Chucai, a functionary from the Khitai people, dissuaded him from this path through appealing to his selfishness. Chinese peasants taxed on their surplus would enrich Genghis Khan far more than enlarging his herds. Rather than focus on primary production, Genghis Khan could sit atop a more complex economic system and extract rents.

Most of you at this point can see the general framework then. For thousands of years, pastoralist people of the Inner Asian steppe and forest would extract rents out of the oikoumene by threatening them with force. The reason the East Roman Empire did not face the Hunnic onslaught during the lifetime of Attila is that they paid the horde tribute. Imperial China did the same during some periods. In other instances, civilized states found in the barbarians of the steppe useful confederates. The Tang dynasty did not collapse during the 750s because of the intervention of the Uyghurs, who suppressed the rebellion of An Lushan. In 9th century Baghdad the rise of the Turks was enabled by their usefulness in court politics and distance from any given faction.

The rise of the “gunpowder empires” during the 16th century and the eventual closing of the Inner Asian frontier with the crushing of the last embers of the Oirat confederacy between the Russian and Chinese Empires in the 18th century marked the end of thousands of years of interaction between the farmland and pasture.

But this makes us ask: when did this dynamic begin? I don’t think it was primordial. It was invented and developed over time through trial and error. I believe that the initial instinct of pastoralists was to turn farmland into pasture for his herds. This was Genghis Khan’s instinct. The rude barbarian that he was he had not grown up in the extortive system which more civilized barbarians, such as the Khitai, had been habituated to.

In these situations where pastoralists expropriated the land, there wouldn’t have been an opportunity for the farmer to raise a family. Barbarian warlords throughout history have aspired to be rich by plundering from the civilized the peoples…but would the earliest generations have understood the complexity of the institutions that they would have to extract rents out of if there wasn’t a precedent?

Instead of conventional historical dynamics of predatory elites and static peasantry, a better way to understand what occurred with the incursion of steppe pastoralists during the Bronze Age might be a simple ecological model of intra-specific competition. In a pre-state society defined by clan and tribal ties, steppe elites may have seen the farmers who were earlier residents in the territories which they were expanding into as competitors rather than resources from which a life of leisure might be obtained. In other words, instead of conquest, the dynamic was of animal competition.

Of course, pre-modern societies did not have totalitarian states and deadly technology. Rapid organized genocide in a way that we would understand was unlikely to have happened. Rather, in a world on the Malthusian margin, a few generations of deprivation may have resulted in the rapid demographic extinction of whole cultures. You don’t need to kill them if they starve because they were driven off their land.

In fact, we have some precedent of this historically. The Spaniards were intent on extracting rents out of the native peoples of the New World and living a life of leisure, but in many areas disease and exploitation resulted in demographic collapse. Imagine a conquest elite as vicious as the Spaniards, but without thousands of years of precedent that conquered peoples were more useful alive rather than dead. 

Addendum: The fraction of haplogroup M, which is probably derived from Pleistocene South Asians, is greater than 50% in places like Sindh. This indicates that the steppe migrations were strongly male biased in the initial generations.