Iron Age bottleneck of the Proto-Fennic population in Estonia

Demographic data and figures derived from Estonian Iron Age graves, by Raili Allmäe, Papers on Anthropology (2018) 27(2).

Interesting excerpts (emphasis mine):

Introduction

Inhumation and cremation burials were both common in Iron Age Estonia; however, the pattern which burials were prevalent has regional as well temporal peculiarities. In Estonia, cremation burials appear in the Late Bronze Age (1100–500 BC), for example, in stone-cist graves and ship graves, although inhumation is still characteristic of the period [28, 18]. Cremation burials have occasionally been found beneath the Late Bronze Age cists and the Early Iron Age (500 BC–450 AD) tarand graves [30, 28]. In south-eastern Estonia, including Setumaa, the tradition to bury cremated human remains in pit graves also appeared in the Bronze Age and lasted during the Pre-Roman period (500 BC–50 AD) and the Roman Iron Age (50–450 AD), and even up to the medieval times [30, 23, 33, 9]. During the Early Iron Age, cremations appear in cairn graves and have occasionally been found in many Pre-Roman early tarand graves where they appear with inhumations [27, 28, 19, 20, 21, 22, 24]. In Roman Iron Age tarand graves, cremation as well inhumation were practiced [28, 36, 37]; however, cremation was the prevailing burial practice during the Roman Iron Age, for example, in tarand graves in south-eastern Estonia [30, 28]. Roman Iron Age (50 AD–450 AD) burial sites have not been found in continental west Estonia [28, 38]). At the beginning of the Middle Iron Age (450–800 AD), burial sites, for example stone graves without a formal structure, like Maidla I, Lihula and Ehmja ‘Varetemägi’, appear in Läänemaa, west Estonia; in these graves cremations as well inhumations have been found [39, 48]. Like underground cremation burial, the stone grave without a formal structure was the most common grave type during the Late Iron Age (800– 1200 AD) in west Estonia [39, 35, 48]. In south-eastern and eastern Estonia, sand barrows with cremation burials appeared at the beginning of the Middle Iron Age. Cremation barrows are attributed to the Culture of Long Barrows and are most numerous in the villages Laossina and Rõsna in northern Setomaa, on the western shore of Lake Peipsi [8, 48]. Apparently during the Iron Age, the practiced burial customs varied in Estonia.

cist-grave-tarand
Typical prehistoric Estonian graves. Top: Cist-graves common during the Bronze Age, by Terker (GNU FDL 1.2). Bottom: Tarand graves of the Iron Age, by Marika Mägi (2017)

Abstract:

Three Iron Age cremation graves from south-eastern Estonia and four graves including cremations as well inhumations from western Estonia were analysed by osteological and palaeodemographic methods in order to estimate the age and sex composition of burial sites, and to propose some possible demographic figures and models for living communities.

The crude birth/death rate estimated on the basis of juvenility indices varied between 55.1‰ and 60.0‰ (58.5‰ on average) at Rõsna village in south-eastern Estonia in the Middle Iron Age. The birth/death rates based on juvenility indices for south eastern graves varied to a greater degree. The estimated crude birth/death rate was somewhat lower (38.9‰) at Maidla in the Late Iron Age and extremely high (92.1‰) at Maidla in the Middle Iron Age, which indicates an unsustainable community. High crude birth/death rates are also characteristic of Poanse tarand graves from the Pre-Roman Iron Age – 92.3‰ for the 1st grave and 69.6‰for the 2nd grave. Expectedly, newborn life expectancies are extremely low in both communities – 10.8 years at Poanse I and 14.4 years at Poanse II. Most likely, both Maidla I and Poanse I were unsustainable communities.

tarand-graves-estonia
Locations of the investigated Estonian Iron Age graves. Map by R. Allmäe

According to the main model where the given period of grave usage is 150 years, the burial grounds were most likely exploited by communities of 3–14 people. In most cases, this corresponds to one family or household. In comparison with other graves, Maidla II stone grave in western Estonia and Rõsna-Saare I barrow cemetery in south-eastern Estonia could have been used by a somewhat larger community, which may mean an extended family, a larger household or usage by two nuclear families.

More papers on the same subject by the author – who participated in the recent Mittnik et al. (2018) paper – include Observations On Estonian Iron Age Cremations (2013), and The demography of Iron Age graves in Estonia (2014).

Fast life history in Iron Age Estonia

While the demographic situation in the Gulf of Finland during the Iron Age is not well known – and demography is always difficult to estimate based on burials, especially when cremation is prevalent – , there is a clear genetic bottleneck in Finns, which has been estimated precisely to this period, coincident with the expansion of Proto-Fennic.

estonian-pca
PCA of Estonian samples from the Bronze Age, Iron Age and Medieval times. Tambets et al. (2018, upcoming).

The infiltration of N1c lineages in Estonia – the homeland of Proto-Fennic – happened during the Iron Age – as of yet found in 3 out of 5 sampled Tarand graves – , while the previous period was dominated by 100% R1a and Corded Ware + Baltic HG ancestry. With the Iron Age, a slight shift towards Corded Ware ancestry can be seen, which probably signals the arrival of warrior-traders from the Alanino culture, close to the steppe. They became integrated through alliances and intermarriages in a culture of chiefdoms dominated by hill forts. Their origin in the Mid-Volga area is witnessed by their material culture, such as Tarand-like graves (read here a full account of events).

This new political structure, reminiscent of the chiefdom system in Sintashta (with a similar fast life history causing a bottleneck of R1a-Z645 lineages), coupled with the expansion of Fennic (and displaced Saamic) peoples to the north, probably caused the spread of N1c-L392 among Finnic peoples. The linguistic influence of these early Iron Age trading movements from the Middle Volga region can be seen in similarities between Fennic and Mordvinic, which proves that the Fenno-Saamic community was by then not only separated linguistically, but also physically (unlike the period of long-term Palaeo-Germanic influence, where loanwords could diffuse from one to the other).

NOTE. Either this, or the alternative version: an increase in Corded Ware ancestry in Estonia during the Iron Age marks the arrival of the first Fennic speakers ca. 800 BC or later, splitting from Mordvinic? A ‘Mordvin-Fennic’ group in the Volga, of mainly Corded Ware ancestry…?? Which comes in turn from a ‘Volga-Saamic’ population of Siberian ancestry in the Artic region??? And, of course, Palaeo-Germanic widely distributed in North-Eastern Europe with R1a during the Bronze Age! Whichever model you find more logical.

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