Long-term matrilineal continuity in a nonisolated region of Tuscany

[Pax Augusta]

The female ancestor's tale: Long-term matrilineal continuity in a nonisolated region of Tuscany by Leonardi et al. Am J Phys Anthr (2018).


On American Journal of Physical anthropology a new paper (behind paywall) has been published: The female ancestor’s tale: Long‐term matrilineal continuity in a nonisolated region of Tuscany. It's possible to read the full paper here.

Excerpts:

"Here we analyze North-western Tuscany, a region that was a corridor of exchanges between Central Italy and the Western Mediterranean coast.

We newly obtained mitochondrial HVRI sequences from 28 individuals, and after gathering published data, we collected genetic information for 119 individuals from the region. Those span five periods during the last 5,000 years: Prehistory, Etruscan age, Roman age, Renaissance, and Present-day. We used serial coalescent simulations in an approximate Bayesian computation framework to test for continuity between the mentioned groups.


In all cases, a simple model of a long-term genealogical continuity proved to fit the data better, and sometimes much better, than the alternative hypothesis of discontinuity.

The low number of samples analyzed requires some caution in the interpretation. Because we did not test for gene flow, it is at this stage impossible to reject it, but our results suggest at least significant levels of genealogical continuity. Moreover, as it has not been possible to obtain more precise information on the age of the Eneolithic samples, they were grouped together considering the average archaeological period of interest, which may cause a bias in the analyses. (…)"

(…)

However, when adding the Etruscan sample to the model we observe both an increase of the fit for the model simulating continuity and a strong decrease of the model misclassification (below 10%). The pattern of genetic differentiation between the Eneolithic sample on the one hand and the Roman, Renaissance and Modern groups on the other, supports continuity in the small area encom-passed in North-western Tuscany, but also suggests that an alterna- tive model may also explain the results. Adding the Etruscans clarifies the pictures, increasing the statistical support for continuity; clearly, our samples show high levels of continuity when considering the whole Tuscan region as a genetic reservoir during the Iron Age.




The posterior distributions of the parameters confirm a high degree of genetic isolation in the sampled population, with very small values for the female effective population sizes across time. Such values, in particular the Neolithic ones, are in accord with the estimates obtained in similar studies, both in Tuscany (Ghirotto et al., 2013) and in France (Rivollat et al., 2017).

Taken at their face value, our results do not show any major shift in the composition of the maternal ancestry of the population, across 50 centuries. This does not mean that no demographic process of relevance has affected the population, and indeed the higher diversity accumulating in time is the likely consequence of immigrating people, enriching the mitochondrial gene pool.


(…) the population of the current Lucca province appears to have retained very ancient mitochondrial features, despite occupying a geographical corridor between the Ligurian and the Tyrrhenian coast, and despite not showing the persistence of unique cultural traits through the centuries.



Another possibility is that that the different populations passing through the area (Etruscans, Romans, and Lombards) had a consistent social and/or sex bias. An example of similar patterns has been observed several times. Between the Late Neolithic and the Early Bronze Age, female exogamy in patrilocal society has been observed in Southern Germany (Knipper et al., 2017); during the Bronze Age the migrations toward Europe from the steppes appears to have consisted prevalently of males (Goldberg, Günther, Rosenberg, & Jakobsson, 2017); and in more recent periods in the Canary Islands, the female ancestry maintains a significant amount of autochthonous lineages, while the male ancestry was strongly influenced by the European colonization (Fregel et al., 2009, b).

It is well known that military invasions may not have a significant genetic impact upon the invaded population (Schiffels et al., 2016; Sokal, Oden, Walker, Di Giovanni, & Thomson, 1996;Weale,Weiss, Jager, Bradman, & Thomas, 2002), especially at the mitochondrial level, because of the limited size of a sustainable army, and of the fact that armies are generally composed mostly or only of males. Even if a substantial share of invaders decided to remain and settle the region, this form of gene flow would affect mostly or only the paternal lineages, rather than the maternal ones. We can also hypothesize the immigration of a number of people (e.g., Romans, Lombards) that may have acted as ruler of the region, remaining socially (and so genetically) separated by the local population, and leaving few (if any) traces in the gene pools of the local population."

Abstract

Objectives

With the advent of ancient DNA analyses, it has been possible to disentangle the contribution of ancient populations to the genetic pool of the modern inhabitants of many regions. Reconstructing the maternal ancestry has often highlighted genetic continuity over several millennia, but almost always in isolated areas. Here we analyze North‐western Tuscany, a region that was a corridor of exchanges between Central Italy and the Western Mediterranean coast.

Materials and methods

We newly obtained mitochondrial HVRI sequences from 28 individuals, and after gathering published data, we collected genetic information for 119 individuals from the region. Those span five periods during the last 5,000 years: Prehistory, Etruscan age, Roman age, Renaissance, and Present‐day. We used serial coalescent simulations in an approximate Bayesian computation framework to test for continuity between the mentioned groups.

Results

Our analyses always favor continuity over discontinuity for all groups considered, with the Etruscans being part of the genealogy. Moreover, the posterior distributions of the parameters support very small female effective population sizes.

Conclusions

The observed signals of long‐term genetic continuity and isolation are in contrast with the history of the region, conquered several times (Etruscans, Romans, Lombards, and French). While the Etruscans appear as a local population, intermediate between the prehistoric and the other samples, we suggest that the other conquerors—arriving from far—had a consistent social or sex bias, hence only marginally affecting the maternal lineages. At the same time, our results show that long‐term genealogical continuity is not necessarily linked to geographical isolation.

[Angela]

Thanks, Pax, very interesting.

Looks like half of the samples are some form of H2a, and the majority of the H2a are H2a2a1. What's interesting to me, in light of speculation that it is an IE lineage, although originally from the north Caucasus, is that it's already present in Lucca province as early as 3000 BC.

Isn't that too early for the Indo-Europeans reaching Italy? I thought the earliest date was sometime around 2200 BC?

I briefly skimmed it but don't see the "Etruscan" results, although I do remember there was H2a2a among them, as well.

Another interesting thing I notice is that almost all of the Roman Era samples are H2a2a.

It will be really interesting to see if different areas of Italy, including other places in northern Italy, have a different pattern in terms of mtDna. If they do it will just support what some of us have long maintained, and Ralph and Coop maintained in their paper based on IBD chunks i.e. structure in Italy is very old. I really wish they had ancient samples from the Lunigiana, particularly in light of the Statue Stele. Jean Manco, rest her soul, was always very interested in them.

https://journals.plos.org/plosbiolog...l.pbio.1001555

https://it.wikipedia.org/wiki/Statue_stele

http://www.statuestele.org/en/

Interesting also that mtDna ROa and M in the Neolithic. So much for it all came during the days of the Roman Empire.

[Pax Augusta]

Thanks, Pax, very interesting.

Looks like half of the samples are some form of H2a, and the majority of the H2a are H2a2a1. What's interesting to me, in light of speculation that it is an IE lineage, although originally from the north Caucasus, is that it's already present in Lucca province as early as 3000 BC.

Isn't that too early for the Indo-Europeans reaching Italy? I thought the earliest date was sometime around 2200 BC?

I briefly skimmed it but don't see the "Etruscan" results, although I do remember there was H2a2a among them, as well.

Another interesting thing I notice is that almost all of the Roman Era samples are H2a2a.

All what we know about "Etruscan" results is this. According to Gail Tonnesen, based on Ghirotto 2013, ancient Etruscan samples were mostly mtDNA U5 and mtDNA JT (of which the overwhelming majority belonged to mtDNA J), and a minority was mtDNA H1b.




Taken from other forums. I have likely forgotten many others.

Ancient samples with H2a2a1:

1) Roman from London (50-70 AD)

2) Anglo-Saxon from Hinxton (690-881 AD)

3) Proto-Bulgarian from Nojarevo (700-900 AD)

4) Proto-Bulgarian from Tuhovishte (800-1000 AD)

5) Slav from Detkovice, Czechia (11th c. AD)


Ancient samples with H2a2a:

1) Hungarian Scythian (3th c. BC?)

Interesting also that mtDna ROa and M in the Neolithic. So much for it all came during the days of the Roman Empire.

Indeed. Ironically, without ancient DNA, these mtDNAs in modern-day samples were often considered as evidence of very recent arrivals from Near East. Instead, they were wrong, these mtDNAs were already there for at least 5000 years.

[Pax Augusta]

It will be really interesting to see if different areas of Italy, including other places in northern Italy, have a different pattern in terms of mtDna. If they do it will just support what some of us have long maintained, and Ralph and Coop maintained in their paper based on IBD chunks i.e. structure in Italy is very old. I really wish they had ancient samples from the Lunigiana, particularly in light of the Statue Stele. Jean Manco, rest her soul, was always very interested in them.

https://journals.plos.org/plosbiolog...l.pbio.1001555

https://it.wikipedia.org/wiki/Statue_stele

http://www.statuestele.org/en/

Sooner or later a study on Lunigiana should come out, they've been working on it for years.