434: High‑coverage genomes recast Japan's prehistoric demography

Ishiya K et al., PNAS - This episode examines a PNAS study that reports two high-coverage ancient human genomes from mainland Japan (an Initial Jomon >67× and a Middle Yayoi >46×). The genomes enable diploid genotyping, demographic reconstructions, ancestry modeling, and AMY1 copy-number analysis that reshape understanding of Jomon and Yayoi histories. Key terms: ancient DNA, Jomon, Yayoi, AMY1, population history. Study Highlights:The authors sequenced two low-contamination, high-coverage genomes from mainland Japan (IY1, Initial Jomon; DO, Middle Yayoi) enabling diploid analyses and CNV inference. Demographic reconstructions show divergent post-LGM trajectories: long-term stability with no expansion in the Jomon lineage and gradual sustained growth in the Yayoi-related ancestral population. Admixture and f-statistics indicate substantial continental Northeast Asian ancestry in the Yayoi individual and genetic continuity between the Yayoi and present-day mainland Japanese. High AMY1 copy numbers (~9–10) in both individuals suggest starch-relevant variation existed before large-scale rice farming. Conclusion:High-coverage ancient genomes from mainland Japan reveal contrasting population histories for Jomon and Yayoi lineages and show that elevated AMY1 copy-number variation relevant to starch consumption predates intensive rice agriculture, refining models of Japanese population formation. Music:Enjoy the music based on this article at the end of the episode. Article title:High-coverage ancient genomes reveal divergent population histories and prehistoric starch-related genetic variation in Japan First author:Ishiya K Journal:PNAS DOI:10.1073/pnas.2606162123 Reference:Ishiya K., Mizuno F., Gojobori J., Kumagai M., et al. High-coverage ancient genomes reveal divergent population histories and prehistoric starch-related genetic variation in Japan. Proc Natl Acad Sci U S A. 2026;123(30):e2606162123. doi:10.1073/pnas.2606162123 License:This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/ Support:Base by Base is independent and ad-free — no sponsors, no paywall. If an episode was worth your time, chip in and keep the papers audited and the original songs coming:❤️ Support monthly: https://buy.stripe.com/cNifZhclVebvagk2JDgEg01☕ One-time donation: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00 More at basebybase.com On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics. Episode link: https://basebybase.com/episodes/high-coverage-ancient-genomes-japan QC:This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-08-06. QC Scope:- article metadata and core scientific claims from the narration- excludes analogies, intro/outro, and music- transcript coverage: Audited the transcript sections describing (1) sampling of two high-coverage genomes (IY1 and DO), (2) authenticity checks and sequencing depth, (3) demographic inferences (PSMC/SMC++), (4) AMY1 copy-number findings, (5) ancestry and admixture contexts, (6) admixture timing, and (7) the dual-structure model; excluded n- transcript topics: Two high-coverage mainland Japan genomes (IY1 Jomon, DO Yayoi); Petrous bone sampling and ancient DNA authentication; PSMC/SMC++ demographic inferences post-LGM; AMY1 copy-number variation and starch-diet adaptation; Ancestry and continental admixture in Yayoi vs Jomon; Admixture timing via LD decay and related methods QC Summary:- factual score: 10/10- metadata score: 10/10- supported core claims: 5- claims flagged for review: 0<...