Selection over migration in Rome

Ancient Roman declines in education‑linked polygenic scores may reflect differential fertility or selection within the local population rather than simply incoming migrants changing the gene pool. In a north‑central Italian sample the fluid‑intelligence score falls further after controlling for broad ancestry, implying internal demographic processes (e.g., who had surviving children) mattered. — If true, this reframes ancient‑DNA narratives from a migration‑only story to one that foregrounds selection and demographic structure — a cautionary model for interpreting genetic change in history and for contemporary debates that link genes, cognition, and migration.