Kinship practices in the early state El Argar society from Bronze Age Iberia

Abstract

The Early Bronze Age in Europe is characterized by social and genetic transformations, starting in the early 3rd millennium BCE. New settlement and funerary structures, artifacts and techniques indicate times of change with increasing economic asymmetries and political hierarchization. Technological advances in metallurgy also played an important role, facilitating trade and exchange networks, which became tangible in higher levels of mobility and connectedness. Archeogenetic studies have revealed a substantial transformation of the genetic ancestry around this time, ultimately linked to the expansion of steppe- and forest steppe pastoralists from Eastern Europe. Evidence for emerging infectious diseases such as Yersinia pestis adds further complexity to these tumultuous and transformative times. The El Argar complex in southern Iberia marks the genetic turnover in southwestern Europe ~ 2200 BCE that accompanies profound changes in the socio-economic structure of the region. To answer the question of who was buried in the emblematic double burials of the El Argar site La Almoloya, we integrated results from biological relatedness analyses and archaeological funerary contexts and refined radiocarbon-based chronologies from 68 individuals. We find that the El Argar society was virilocally and patrilineally organized and practiced reciprocal female exogamy, supported by pedigrees that extend up to five generations along the paternal line. Synchronously dated adult males and females from double tombs were found to be unrelated mating partners, whereby the incoming females reflect socio-political alliances among El Argar groups. In three cases these unions had common offspring, while paternal half-siblings also indicate serial monogamy or polygyny.

Patrilineal segmentary systems provide a peaceful explanation for the post-Neolithic Y-chromosome bottleneck

“…In particular, males tend to share more often the same haplogroup of the Y chromosome, whereas there is a greater diversity of haplogroups for mtDNA 67 – 77 . In addition, reconstructed pedigrees show more first and second-degree related males than females 67 , 69 , 70 , 72 , 74 – 77 . These observations have been interpreted as the result of patrilocal residence (with varying degrees of compliance with the rule), with males more likely to remain in their birthplace and females more likely to migrate between sites.…”

BREADR: An R Package for the Bayesian Estimation of Genetic Relatedness from Low-coverage Genotype Data

“…To test the performance of BREADR on empirical data, we analyse a pseudo-haploid Eigenstrat data set ( [13]) generated from prehistoric individuals who were buried at the Early Bronze Age site La Almoloya in today's Spain ( [20]). This data was generated from 1240k capture ( [9]) data using pileupcaller 3 with mapping and sequence quality filtering parameters -q 30 and -Q30, and the -randomHaploid flag.…”

“…For details on the bionformatic processing of the raw sequence data, and for data quality statistics such as coverage, we refer the reader to the original study ( [20]).…”

“…We tested our method on the empirical data from the Early Bronze Age site of La Almoloya, in Spain ( [20]) using the same parameters as for the simulated data. A plot of the overall relatedness can be found in Figure 9.…”

“…Secondly, it is often used to exclude all but one of a group of closely-related individuals for reducing bias in downstream genetic analyses which rely on independent samples of the allele frequency distribution, and thus could lead to biased results. Recently, due to methodological improvements in sampling, DNA extraction, library preparation and capture techniques, archaeogenetics studies have also begun to explore focused regional studies, aimed at investigating kinship and social organisation in groups of burials or even entire graveyards/burial grounds ( [10,18,1,24,17,20]). Robust estimates of biological relatedness are a key source of information in concert with archaeological and anthropological lines of evidence (among others) for inferring kinship practices in past societies.…”