Old Demographics
High-resolution genomic history of early medieval Europe
Leo Speidel et al.
Nature, 2 January 2024, Pages 118-126
Abstract:
Many known and unknown historical events have remained below detection thresholds of genetic studies because subtle ancestry changes are challenging to reconstruct. Methods based on shared haplotypes and rare variants improve power but are not explicitly temporal and have not been possible to adopt in unbiased ancestry models. Here we develop Twigstats, an approach of time-stratified ancestry analysis that can improve statistical power by an order of magnitude by focusing on coalescences in recent times, while remaining unbiased by population-specific drift. We apply this framework to 1,556 available ancient whole genomes from Europe in the historical period. We are able to model individual-level ancestry using preceding genomes to provide high resolution. During the first half of the first millennium CE, we observe at least two different streams of Scandinavian-related ancestry expanding across western, central and eastern Europe. By contrast, during the second half of the first millennium CE, ancestry patterns suggest the regional disappearance or substantial admixture of these ancestries. In Scandinavia, we document a major ancestry influx by approximately 800 CE, when a large proportion of Viking Age individuals carried ancestry from groups related to central Europe not seen in individuals from the early Iron Age. Our findings suggest that time-stratified ancestry analysis can provide a higher-resolution lens for genetic history.
How Deep Are the Roots of Female Empowerment? Population Diversity and Gender Inequality
Trung Vu
Oxford Bulletin of Economics and Statistics, forthcoming
Abstract:
I study the impact of population diversity, determined predominantly over the prehistorical out-of-Africa migration process of anatomically modern humans, on present-day gender inequality. Leveraging variations across countries and individuals residing in the same country but descending from different prehistorically indigenous ethnic groups, I find that deep-rooted population diversity negatively affects women's economic and political empowerment. I provide several explanations for this finding. First, preindustrial societies with higher interpersonal diversity tended to experience early technological development, which primarily translated into fertility growth associated with lower women's social status during the Malthusian epoch. Second, population diversity was conducive to economic specialization, which co-evolved with and amplified the traditional gendered division of labour particularly in preindustrial societies with long agricultural histories. Finally, the early formation and prevalence of unequal gender roles in preindustrial times would gradually increase intergenerationally transmitted cultural beliefs about gender inequality, leading to wide and persistent disparities in gender roles across the contemporary world.
Dating the beginning of urbanization in Central Mexico: A high-resolution chronology of the Middle Formative Period at Tlalancaleca
Tatsuya Murakami, Alexander Jurado & Shigeru Kabata
Radiocarbon, forthcoming
Abstract:
Research by the Tlalancaleca Archaeological Project (PATP) has corroborated modifications to the Middle Formative chronology in Puebla-Tlaxcala (Lesure et al. 2006, 2014) using Bayesian modeling on 26 radiocarbon dates from Tlalancaleca. The present study is the first to evaluate the region's Middle Formative chronology with radiocarbon dates from superposed stratigraphy. Nine Bayesian models were constructed with different combinations of radiocarbon dates and OxCal's phase and sequence functions to determine the beginning and end of the Texoloc phase. Results place the Tlatempa-Texoloc transition at around 650 cal BC and the Texoloc-Tezoquipan transition at around 500 cal BC. The OxCal Interval function supports a timespan of approximately 150 years for the duration of the Texoloc phase. These results suggest the process of initial urbanization in Central Mexico was a rapid one.
Lake-centred sedentary lifestyle of early Tibetan Plateau Indigenous populations at high elevation 4,400 years ago
Xiaoyan Yang et al.
Nature Ecology & Evolution, December 2024, Pages 2297-2308
Abstract:
The onset of sedentism on the Tibetan Plateau is often presumed to be associated with the dispersal of agriculture or farmers from archaeological sites located in the low elevation margins of the plateau. Previous studies of the plateau assumed that all foragers were probably mobile, but few systematic excavations at forager sites have been conducted to inform us about their settlement patterns. Here we report the world's highest elevation sedentary way of living exhibited by the Mabu Co site at 4,446 metres above sea level, deep in the interior of the Tibetan Plateau 4,400-4,000 years ago. Our interdisciplinary study indicates that the site was occupied by Indigenous inhabitants of the plateau, representing the earliest known DNA evidence of foragers who predominantly harbour the southern plateau ancestry. The evidence shows that they had a sedentary lifestyle primarily supported by fishing at nearby lakes, supplemented by mammal and bird hunting, as well as small-scale exchanges of millet and rice crops.