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Population Issues and General Etruscan Modeling

Posted by EP1987 on 20 Feb 2013 at 12:45 GMT

The problem for the Anatolian sample is not only recent immigration by the Turks. As non-Indo-Europeans, the Etruscans in Anatolia would already have been a small and marginalized population there in 1000 BC, potentially genetically isolated from their neighbors for several thousand years. Then from 1000 BC to the modern era, there was continuous additional immigration into Anatolia, of which the Ottoman conquest was only one chapter. It's also possible that the entire Etruscan ethnic group (perhaps meaning a few hundred refugees) could have left Anatolia to resettle in Italy.

So any ancient Etruscan DNA in Anatolia could well be extinct or quite rare in the modern population of Turkey. In fact this is supported by the authors' own premise. They found Etruscan mtDNA in a modern Italian population because they looked in Volterra, not Florence or Palermo, and this is after 2000 years. So a small and general DNA sample from Turkey as a whole, after 3000 years, can't be counted on to identify an isolated ancient minority population up in the hills somewhere. If they ever existed. If they didn't disappear long ago.

What this study has shown is that ancient Etruscan mtDNA is at least not common in Turkey today, and that's certainly useful to know. A future large-scale database of DNA from modern Turkey, or DNA from Bronze Age Anatolian burials, might positively prove Etruscan origins there. But a lack of DNA will never positively disprove it from silence, given the possibility of a small ethnic group totally disappearing from the detectable record.

Regarding continuity of the ancient to modern Tuscans, an essential issue is class. The DNA in elaborate Etruscan tombs is of the aristocracy. This could be quite distinct from that of the large majority of the ancient Etruscan population -- certainly if the upper class was a thin layer of foreign settlers/conquerers. This applies really even with an "indigenous" model, if by this we mean the Villanovan culture -- which was just another elite that had arrived from Central Europe a few hundred years earlier.

What is unexpected about this study is that it examined only mtDNA. Perhaps there is a technical explanation for this or it is simply the researchers' current undertaking, among others. Settlement in Italy could easily have been by Etruscan-speaking males only. One possibility is that Etruscan men arrived neither in a migration, nor as conquerors, but as foreign merchants setting up trading depots in Italy, and becoming a bourgeoise ruling class due to their wealth, intermarrying with the Indo-European Villanovan women. Everyone will agree that Etruscan culture is fundamentally influenced by Aegean culture, and the essential thing is that pots don't fly. They, or at least their designs, are brought by men. In all cases, the "Etruscans" in the initial sense can be a very small group which superimposes its language and culture on the region much more than its genes.

I will also mention that modeling of Etruscan origins should definitely not be limited to the three options of indigenous, Anatolian, or Alpine/Central European (Rhaetian). Other strong contenders are Corsica, Iberia, Crete, and the Caucasus Mountains. Given the Etruscans' highly-developed nautical skills they could even have come from more exotic locations beyond the Mediterranean. Historians are oddly quiet even about the fact that they traded for tin in Britain.

Finally indigenous origin for the Etruscans is not a default that wins if no other conclusive proof can be established. There is no explanation for the Villanovans simultaneously adopting Greek culture, while switching to inhumation, which is both un-Villanovan and utterly un-Greek. Advocates of indigenous origin must positively prove it with Bronze Age DNA of their own in Italy, which is directly ancestral to the (male) Etruscans in the tombs. And this should be easy for them, if there was really a single ethnic group living on the same piece of land for 5000 years.

I thank the authors for their hard work on this fascinating subject and apologize for some tangents from the present study.

No competing interests declared.

RE: Population Issues and General Etruscan Modeling

GuidoBarbujani replied to EP1987 on 22 Feb 2013 at 10:52 GMT

Human genetic studies often evoke polarized reactions. Some write in their posts that archaeology is all we need to understand our past, others ask geneticists exceedingly complicated questions. However, science has little to do with establishing a historical reality (that would be far too difficult). Instead, it has a lot to do with testing testable hypotheses. Geneticists can describe the DNAs of past and present people, and then see what is the most likely hypothesis accounting for the available data. It is hard to imagine we shall ever be able to properly compare hypotheses on possible Etruscan origins in Anatolia, the Alps, Corsica, Iberia, Crete, and the Caucasus, let alone in more exotic locations.

Thus, we can answer only two of the many questions asked in this comment: (1) It will take many years before a decent number of past populations are typed for DNA markers other than mtDNA; (2) We did consider the possibility that the Etruscans might have been a social elite (Belle et al. 2006), but probably that elite was not so small, since traces of their DNAs are still present in Tuscany. Other than that, so far genetic studies have been able to say something about the Etruscans. Not much, but much better than nothing, we think.

1. In 2004 we typed the first Etruscan individuals, from classical Etruria, Capua and Adria, showing that their mtDNAs are similar, but seldom identical, to those of current Tuscans, and observing some degree of similarity with Anatolian populations too (Vernesi et al. 2004).
2. We formally tested by serial coalescent simulations the hypothesis of a genetic continuity between Tuscans and Etruscans, and found no support for it (Belle et al. 2006).
3. Achilli et al. (2007) observed a degree of similarity between mtDNAs in modern Tuscans and Anatolians, which they interpreted as a consequence of an Etruscan origin in Anatolia. Because no such similarity was apparent between Tuscans and Etruscans, Achilli et al. (2007) concluded that the ancient data were flawed.
4. Mateiu and Rannala (2008) reanalyzed by a Bayesian method the Etruscan mtDNA dataset, showing that there was no reason to suspect it might contain systematic errors.
5. We expanded the Etruscan sample, and by ABC found evidence for a genealogical continuity between classical Etruria (i.e. excluding Capua and Adria) and some local Tuscan populations. Also, we showed by the IM method that such Tuscans populations and two samples from Anatolia do have something in common (as proposed by Achilli et al. 2007), but that the last contact between their ancestors long predated the onset of the Etruscan culture in Italy (Ghirotto et al. 2013).

All this can certainly be improved. Sample sizes can be expanded and a greater number of populations, modern as well as ancient, can be typed for many DNA markers. Unfortunately, no genetic study of the Villanovian people seems possible, because they cremated their dead. Once new data will be available, what now appears to be the most likely hypothesis may or may not be confirmed. For the time being, there is little doubt that the available evidence does not suggest an Etruscan origin outside Italy.

Achilli A, Olivieri A, Pala M, Metspalu E, Fornarino S, et al. (2007) Mitochondrial DNA variation of modern Tuscans supports the near eastern origin of Etruscans. Am J Hum Genet 80: 759–768.
Belle EM, Ramakrishnan U, Mountain JL, Barbujani G (2006) Serial coalescent simulations suggest a weak genealogical relationship between Etruscans and modern Tuscans. Proc Natl Acad Sci USA 103: 8012–8017.
Mateiu LM, Rannala BH (2008) Bayesian inference of errors in ancient DNA caused by postmortem degradation. Mol Biol Evol 25: 1503–1511.
Vernesi C, Caramelli D, Dupanloup I, Bertorelle G, Lari M, et al. (2004) The Etruscans: a population-genetic study. Am J Hum Genet 74: 694–704.

No competing interests declared.