Pongsakorn Wangkumhang1,2, Matthew Greenfield1 and Garrett Hellenthal1 1University College London Genetics Institute (UGI), Department of Genetics, Evolution and Environment, University College London, London, WC1E 6BT, United Kingdom; 2National Biobank of Thailand, National Science and Technology Development Agency, Pathum Thani 12120, Thailand Corresponding author: g.hellenthalucl.ac.uk Abstract

We present fastGLOBETROTTER, an efficient new haplotype-based technique to identify, date, and describe admixture events using genome-wide autosomal data. With simulations, we show how fastGLOBETROTTER reduces computation time by an order of magnitude relative to the related technique GLOBETROTTER without suffering loss of accuracy. We apply fastGLOBETROTTER to a cohort of more than 6000 Europeans from 10 countries, revealing previously unreported admixture signals. In particular, we infer multiple periods of admixture related to East Asian or Siberian-like sources, starting >2000 yr ago, in people living in countries north of the Baltic Sea. In contrast, we infer admixture related to West Asian, North African, and/or Southern European sources in populations south of the Baltic Sea, including admixture dated to ∼300–700 CE, overlapping the fall of the Roman Empire, in people from Belgium, France, and parts of Germany. Our new approach scales to analyzing hundreds to thousands of individuals from a putatively admixed population and, hence, is applicable to emerging large-scale cohorts of genetically homogeneous populations.

Footnotes

[Supplemental material is available for this article.]

Article published online before print. Article, supplemental material, and publication date are at https://www.genome.org/cgi/doi/10.1101/gr.275994.121.

Freely available online through the Genome Research Open Access option.

Received July 23, 2021. Accepted June 28, 2022.