Gauls: variations mobility

MOESAN

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more celtic
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a new survey:
Journal Pre-proof
Origin and mobility of Iron Age Gaulish groups in present-day France revealed
through archaeogenomics
Fischer Claire-Elise, Pemonge Marie-Hélène, Ducoussau Isaure, Arzelier Ana,
Rivollat Maïté, Santos Frederic, Barrand Emam Hélène, Bertaud Alexandre, Beylier
Alexandre, Ciesielski Elsa, Dedet Bernard, Desenne Sophie, Duday Henri, Chenal
Fanny, Gailledrat Eric, Goepfert Sébastien, Gorgé Olivier, Gorgues Alexis, Kuhnle
Gertrud, Lambach François, Lefort Anthony, Mauduit Amandine, Maziere Florent,
Oudry Sophie, Paresys Cécile, Pinard Estelle, Plouin Suzanne, Richard Isabelle,
Roth-Zehner Muriel, Roure Réjane, Thevenet Corinne, Thomas Yohann, Rottier
Stéphane, Deguilloux Marie-France, Pruvost Mélanie
 
1
Origin and mobility of Iron Age Gaulish groups in present-day France revealed through1
archaeogenomics2
3
4
Fischer Claire-Elise*1,2, Pemonge Marie-Hélène2, Ducoussau Isaure2, Arzelier Ana2, Rivollat5
Maïté2,3, Santos Frederic2, Barrand Emam Hélène4,5, Bertaud Alexandre6, Beylier6
Alexandre7,8, Ciesielski Elsa8, Dedet Bernard8, Desenne Sophie9,10, Duday Henri2, Chenal7
Fanny5,9, Gailledrat Eric8, Goepfert Sébastien4,5, Gorgé Olivier11 , Gorgues Alexis6, Kuhnle8
Gertrud12, Lambach François2, Lefort Anthony9, Mauduit Amandine4, Maziere Florent8,9,9
Oudry Sophie9,13, Paresys Cécile9,14, Pinard Estelle9,10, Plouin Suzanne5, Richard Isabelle9,14,10
Roth-Zehner Muriel5,15, Roure Réjane8, Thevenet Corinne9,10, Thomas Yohann5,9, Rottier11
Stéphane2, Deguilloux Marie-France*2,16 and Pruvost Mélanie*2,16,+
12
13
14
15
Summary16
The Iron Age period occupies an important place in French history, as the Gauls are17
regularly presented as the direct ancestors of the extant French population. We documented18
here the genomic diversity of Iron Age communities originating from six French regions. The19
49 acquired genomes permitted us to highlight an absence of discontinuity between Bronze20
Age and Iron Age groups in France, lending support to a cultural transition linked to21
progressive local economic changes rather than to a massive influx of allochthone groups.22
Genomic analyses revealed strong genetic homogeneity among the regional groups associated23
with distinct archaeological cultures. This genomic homogenisation appears to be linked to24
+ Lead contact
* Corresponding authors: claire-[email protected]; marie-france.deguilloux@u-bordeaux.fr;
melanie.pruvost@u-bordeaux.fr
1 present address: Department of Archaeology, University of York, King’s Manor Exhibition Square, York,
YO1 7EP, UK
2 UMR 5199 PACEA, CNRS, Université de Bordeaux, 33615 Pessac, France
3 Department of Archaeogenetics, Max Planck Institue for Evolutionary Anthropology, Deutscher Platz 6,
04103 Leipzig, Germany
4 ANTEA-Archéologie, Habsheim, France
5 UMR7044 Archimède, CNRS Université de Strasbourg et Université de Haute-Alsace, Strasbourg et
Mulhouse, France
6 UMR-5607 Ausonius, Université Bordeaux Montaigne, Maison de l’Archéologie, 8 Esplanade des Antilles
33607 Pessac, France
7 Service Archéologie Sète agglopôle mediterranée, 34110, Frontignan, France
8 UMR 5140 - ASM, Université Paul Valéry Montpellier 3, CNRS, Ministère de la Culture, Inrap, F34000
Montpellier, France
9 INRAP, Institut National de Recherche Archéologiques Préventives, 75685 Paris cedex14, France
10 UMR 8215 Trajectoires, CNRS, Université Paris 1 Pantheon Sorbonne, 92023 Nanterre, France
11 Institut de Recherche Biomédicale des Armées, Place Général Valérie André, 91220 Brétigny-sur-Orge,
France
12 Landesamt für Denkmalpflege im Regierungspräsidium Stuttgart Referat 84.2 Operative Archäologie
Dienstsitz Freiburg Günterstalstraße 67, 79100 Freiburg i. Br.
13 UMR-7268 ADES, CNRS, Université Aix-Marseille, EFS, 13015 Marseille, France
14 UMR 7264 CEPAM, CNRS Université Nice Sophia Antipolis, 06357 Nice cedex4, France
15 Archéologie Alsace, 11 rue Champollion 67600 Sélestat, France
16 These authors contributed equally to this work



2
individuals’ mobility between regions as well as gene flow with neighbouring groups from25
England and Spain. Thus, the results globally support a common genomic legacy for the Iron26
Age population of modern-day France that could be linked to recurrent gene flow between27
culturally differentiated communities.28
Introduction29
30
The French Iron Age holds an important place in French history, as Gaulish31
communities are regularly presented to the general public as the direct ancestors of French32
populations. This major interest has led to an impressive number of archaeological studies33
describing Iron Age communities through their material culture and funerary practices and34
questioning their cultural origins and affinities. Despite this interest, questions concerning the35
cultural and biological processes underlying the emergence and expansion of Iron Age36
cultures remain intensely debated. Thus, the transition between the Bronze Age (BA) and the37
Iron Age (IA) was first linked to the rapid shift from bronze to iron technologies between38
Hallstatt B3 and Hallstatt C (approximately 800 BC). However, this clear cut-off does not39
appear to reflect the regional archaeological reality that there was a gradual transition to the40
use of iron instead of a rapid substitution (Verger, 2015). Moreover, the cultural41
transformations associated with the transition span over two centuries encompassing the late42
Bronze Age and the first phase of the Iron Age and appear to have followed different rhythms43
that varied by region (Verger, 2015). Debates also concern the modes of emergence of the44
Late Iron Age culture La Tène, associated with groups generally referred to as ‘Celts’ and45
spread over a large part of Europe, spanning from Bohemia to the Atlantic (Roure, 2020).46
Thus, some authors propose an advent of this cultural entity in Central Europe and Bohemia47
before its expansion through the migration of groups bringing cultural developments from the48
northern Alpine area to the rest of Europe (Kruta, 2000; Brun, 2017). Other authors propose a49
multiregional origin of the La Tène culture through the evolution of a mosaic of cultural50
complexes ('multipolar genesis in networks'; Milcent, 2006) connected by common markers51
such as art without implying major migration. According to this view, the ‘Celts’ would be52
defined as a multitude of related people with different cultural practices (Lejars and Gruel,53
2015).54
The great amount of archaeological data available for Iron Age groups from the55
French territory strikingly contrasts with the near absence of genomic data for the human56
groups concerned. In the archaeology of death, as well as in the study of ancient human group57
dynamics, palaeogenetic analyses have led to considerable advances. From the Palaeolithic to58
the Bronze Age periods, ancient DNA (aDNA) studies have provided arguments59
complementary to the archaeological evidence to reconstruct the dynamics of the groups at60
the European macroregional scale (see Liu et al., 2021 for a recent review), as well as61
discussions on the social functioning of communities at the local scale (documenting, for62
example, residence rules or filiation systems; e.g. Mittnik et al., 2019). Despite the63
considerable increase in palaeogenomic analyses over the last decade, some territories or64
periods remain poorly documented. In that respect, the French territory remained neglected in65
palaeogenomic studies in Europe until the very recent publication of three studies targeting66
this key crossroad region in western Europe (Brunel et al., 2020; Rivollat et al., 2020;67
Seguin-Orlando et al., 2021). Nevertheless, genetic and genomic data for IA period from68
French territory remain scarce, with mitochondrial data for 91 individuals and low-coverage69
genomes for 19 individuals (Fischer et al., 2018, 2019; Brunel et al., 2020). To date, the70
underrepresentation of IA populations in palaeogenomic studies, compared with prior71
periods, can be extended to the European scale, with a total of 44 mitochondrial sequences72
3
from Germany, Spain and Italy (Knipper et al., 2014, Núñez et al., 2016, Serventi et al.,73
2018) and a total of 27 genomic data points from England (Martiniano et al., 2016; Schiffels74
et al., 2016), Bulgaria (Mathieson et al., 2018), Croatia (Mathieson et al., 2018), Spain75
(Olalde et al., 2019), Hungary (Gamba et al., 2014), Montenegro (Allentoft et al., 2015),76
Estonia (Saag et al., 2019) and Germany (Furtwängler et al., 2020).77
These observations are particularly frustrating given that only the acquisition of78
representative palaeogenomic data for French Iron Age groups and their comparison with79
archaeological data can allow to directly characterise the biological processes potentially80
involved in the cultural transformations documented between the Bronze Age and Iron Age81
or between the Early and the Late Iron Age periods. Furthermore, compelling genomic data82
for these ancient communities provide the only way to test for correlation between the83
cultural and biological diversities of groups and question modes of exchanges between84
populations. Finally, genomic data obtained at the local scale can provide major insights into85
the social organisation of communities. For older periods, whether the Neolithic or Bronze86
Age, palaeogenomic studies have revealed recurrent patrilocal residence rules, patrilineal87
filiation systems or differences in social level (see, for example, Lacan et al., 2011; Mittnik et88
al., 2019). For the Iron Age, the indirect testimonies left by Greeks and Romans (such as De89
Bello Gallico from Julius Caesar, even if they must be considered with caution) mentioned a90
very hierarchical society characterised by a patrilineal system of filiation. Thus, obtaining91
genomic data for the Iron Age communities represents a unique opportunity to compare92
biological, archaeological and textual data.93
The outstanding questions presented above and the great potential of the combination94
of archaeological, textual and genomic data in an attempt to resolve them motivated us to95
better document the genomic diversity of the Gaulish populations. For this purpose, we96
targeted 145 individuals from 27 sites spread over the extant French territory and distributed97
throughout the IA period to optimise our chance of documenting the gene pool of a98
representative set of French Iron Age individuals. The wide chronological distribution of the99
dataset permitted us to address questions of origin and evolution of the groups, whereas the100
wide geographical distribution of the samples allowed us to test for interregional gene flow.101
Notably, some archaeological evidence highlighted particular exchange networks with the102
groups from the surrounding areas, such as the example of the necropolis of Urville-103
Nacqueville, sharing clear archaeological features (roundhouses, Durotrigian burials, etc.)104
with contemporaneous groups from Britain (Lefort et al., 2015). Finally, we also targeted105
sites associated with different funerary practices to better understand the biological identity106
and potential selection of the individuals buried.
 
The Iron Age genomic dataset from France111
112
A total of 145 individuals were targeted for palaeogenomic analyses (Table S1). DNA113
was extracted, and DNA libraries were built with a partial uracil-DNA glycosylase treatment,114
allowing for the assessment of postmortem deamination patterns (2% to 29%) expected for115
ancient DNA data. Initial screening via shotgun sequencing of 1 to 2 million reads was used116
to select libraries with an amount of endogenous DNA above 15%, leading to the exclusion117
of 92 individuals. For the remaining individuals who passed these quality criteria, we118
sequenced the libraries to an average depth of 0.178X (Table S2). We found overall119
negligible level of contamination in our dataset by testing for heterozygosity of polymorphic120
sites on the X chromosome in males (Table S3). The dataset resulting from these successive121Journal Pre-proof
4
quality selections encompasses low-coverage genomes for 49 individuals originating from 27122
sites, dating from the Bronze Age (N = 2) and the Iron Age periods (N = 47). We compiled123
the IA data with 18 low-coverage genomes already published for IA groups from France124
(Brunel et al., 2020), leading to a total of 65 low-coverage genomes distributed in 6125
geographical areas: Alsace (N = 20), Champagne (N = 5), Normandy (N = 3), North (N =126
10), South (N = 18) and Paris Basin (N = 9) (see Figure 1A, STAR Methods and Tables S1127
and S3). The IA dataset is unbalanced in terms of the chronological distribution of the128
individuals, with 11 individuals dated to the Early Iron Age and 54 dated to the Late Iron Age129
period (Figure 1B). This can be partly explained by the funerary treatment and the use of130
cremation (see, for example, Dedet, 2004 for southern France). The few humans remains131
(from southern or north-western France) available for genomic analyses represent deceased132
who escaped cremation and benefited from non-ordinary funerary practices. Therefore, the133
corpus available for genomic analysis may not be representative of the entire population134
living at the time. For instance, for southern France, genetically analysed individuals135
correspond to severed heads (see STAR Methods. site of Le Cailar) or to neonates buried in136
settlements (see STAR Methods. site Le Plan de la Tour). The dataset is also unbalanced in137
terms of regional representativeness, with the Normandy region providing the lowest number138
of genomes due to the low DNA conservation in the coastal Urville-Nacqueville necropolis139
targeted (Table S1). Finally, among the 65 individuals, if 33 were males and 32 were females,140
the sex ratio within each region was unbalanced, with notably more females in Alsace and141
more males in the South (Table S2). With this frame in mind, we analysed our data with142
published ancient individuals (n = 5225) genotyped on the 1240k panel (Mathieson et al.,143
2015) as well with modern (n = 6461) individuals from a panel of modern-day worldwide144
populations genotyped on the Affymetrix Human Origins (HO) panel. From the present145
study’s dataset, 65 individuals with more than 20,000 SNPs on the 1240k panel were used for146
the downstream genome-wide analyses (see STAR Methods and Table S2). We found no147
first-degree relatives among IA individuals from present-day France allowing us to keep the148
full dataset for downstream analyses (see STAR Methods, Table S3 and Figure S4).149
150
We first explored our data qualitatively using principal component analysis (PCA) by151
projecting the ancient genomes onto the genetic variation of an HO set of west Eurasians152
(Figure 1C and S1). French IA individuals fall within the genomic variability of the modern-153
day French population. IA samples from Spain and Great Britain also fall within modern-day154
populations from the same region, highlighting a certain degree of continuity from the Iron155
Age to modern-day populations in western Europe, confirming previous results based on156
mitochondrial DNA (Fischer et al., 2018). The PCA also shows a clinal distribution of our IA157
French samples according to their latitudinal position: the northern samples are closer to the158
extant Great Britain population, and the southern samples are closer to the Spanish population159
(Figure S1). These observations are fully consistent with genomic studies conducted on160
modern Europeans and highlight a geographically and genomic intermediate position of the161
French groups between north-western and south-western European populations (Novembre et162
al., 2008).163
164
165
To test further the genomic variability of the new IA genomes, we grouped the166
individuals among different chrono-cultural groups, i.e., according to their region of origin167
and, when possible, to their dating (Early vs. Late Iron Age): EIA_Alsace (from 800 BC to168
450 BC), LIA_Alsace (from 450 BC to 50 BC), IA_Champagne, IA_Normandy, IA_North,169
IA_Paris_Basin and IA_South. We then carried out a qpWave analysis iterated over all170
individuals in the pool, testing for significant evidence of heterogeneity relative to the171

5
remaining chrono-cultural group (see STAR Methods and Figure 2). Individuals were172
considered genomic outliers from the chronological-cultural group from which they originate173
when the qpWave p value was < 0.05 (Fernandes et al., 2020). This resulted in the174
identification of six individuals as outliers: BES1248, PECH3 and PEY163 stand as outliers175
from the IA_South group, CROI11 from the EIA_Alsace group, COL239 from the176
LIA_Alsace group and GDF1341 from the IA_Paris_Basin group. The analyses at the177
regional level were consequently conducted separately on these individuals and their chrono-178
cultural groups. The outlier status of these special individuals will be further discussed.179
18
 
I just this minute finished reading it. There are so many caveats, starting with low coverage genomes and the lack of balance in terms of numbers between the early and late Iron Age that I have some hesitancy in accepting it.

"The Iron Age period occupies an important place in French history, as the Gauls are regularly presented as the direct ancestors of the extant French population. We documented here the genomic diversity of Iron Age communities originating from six French regions. The 49 acquired genomes permitted us to highlight an absence of discontinuity between Bronze Age and Iron Age groups in France, lending support to a cultural transition linked to progressive local economic changes rather than to a massive influx of allochthone groups. Genomic analyses revealed strong genetic homogeneity among the regional groups associated with distinct archaeological cultures. This genomic homogenisation appears to be linked to individuals’ mobility between regions as well as gene flow with neighbouring groups from England and Spain. Thus, the results globally support a common genomic legacy for the Iron Age population of modern-day France that could be linked to recurrent gene flow between culturally differentiated communities."

https://www.cell.com/action/showPdf?pii=S2589-0042%2822%2900364-9

In my case, thanks to Lazaridis for the heads up.
 
Yes, too small samples and personally I'm not sure of the close cultural assignation of the southern France pop's of the time. "Gaul" in some way, but "Celt"? What seems sure independently of this survey is that internal moves occurred in Gaul during Iron and modified the most western parts of the territory. THis survey seems looking at things from far and high.
 

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