Why did Rome, rather than any of its many rivals in Iron Age Italy, become the core of an empire?
A muddy settlement on the Tiber turns into a machine that can raise armies, write laws that outlive empires, build roads that stitch a continent together, and carry water for millions through aqueducts, while running a Mediterranean-wide bureaucracy for centuries. The usual explanations are familiar: institutions, military discipline, geography, luck. All true, and none of them feels fully satisfying on its own. Many societies possessed some of these advantages. Rome was unusual in how consistently it turned them into scalable institutions.
There is another angle that is rarely discussed, mostly because until recently it was not testable. What if part of Rome’s advantage was carried in its people, as average differences in traits linked to learning, planning, and administration?
Ancient DNA makes it possible to ask that question directly. Using the AADR dataset and educational attainment polygenic scores, Iron Age and Republican-era Romans come out unusually high. Besides exceeding earlier Italian groups, they sit at the top of the entire ancient European distribution, even after accounting for sample age and genomic coverage.
That by itself does not explain the rise of Rome. But it does suggest a sharper hypothesis: Rome’s institutions may have been built and operated by a population that, on average, was unusually well suited to master and scale complex social systems.