Razib Khan One-stop-shopping for all of my content

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?

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