Where we went, written in DNA

The story this dataset tells is, at first, a story about its own gaps. We assembled 19,029 ancient individuals from the Allen Ancient DNA Resource, each carrying a place, a date, a curated ancestry label and, often, a paternal and maternal haplogroup. Yet when we plot those samples through time, 99.6 percent of them are younger than 30,000 years, and more than two-thirds come from Europe. The very window we set out to prioritise — the Out-of-Africa dispersal between 70,000 and 30,000 years ago — contains just sixty-eight individuals, and the African homeland that launched every later migration is represented by fewer samples than a single medieval European cemetery. Any honest reconstruction must therefore separate what the genomes confirm from what we infer around their silences.

The metadata still recovers recognizable structure. Unsupervised DBSCAN on geography and time produced 226 spatio-temporal groups, and several high-scoring connections line up with migrations already supported by genome-wide studies and archaeology: Anatolian farming expansions, Steppe-related movements, and the peopling of Remote Oceania. That agreement is a useful sanity check, not independent confirmation. A top-ranked edge means only that two groups satisfy this model's age, distance and haplogroup-profile rules.

Beyond Eurasia, the founder signatures are equally clean. Every Indigenous American cluster, from Anzick-1 in Pleistocene Montana to the Classic Maya, carries the Beringian Q1b paternal lineage — the fingerprint of a small population that paused in a glacial refugium while sea levels were low, then spread the length of two continents once deglaciation opened the coastal and interior routes. In Remote Oceania, the Mariana Islands' Latte-period people and the settlers of Vanuatu carry East Asian O lineages, the maritime calling-card of the Austronesian expansion that outrigger canoes made possible. In each case the driver is legible: a climate door opening, a technology unlocking new range, or a demographic engine — farming's carrying capacity — pushing one people into another's land.

The deepest and most important migration, however, we can only see in silhouette. The Out-of-Africa dispersal left no in-window genomes in its African or Arabian source. We infer it instead from its descendants: Ust'-Ishim in Siberia and Zlatý kůň and Bacho Kiro in Europe, all near 45,000 years old, with the Oase individual preserving a Neanderthal ancestor only a handful of generations back. From these downstream points, and from the climate record of MIS 3 with its intermittently "green" Arabia, we reconstruct a dispersal threading humid corridors out of Africa during favourable pulses — a confident outcome resting on an inferred route.

The methodological honesty matters as much as the pattern. The multi-gigabyte genotype matrix was not processed, the climate layer provides historical context rather than a causal test, and the clustering depends on a tuned space-time exchange rate. The map is therefore an exploratory hypothesis generator. The clearest message is double-edged: ancient DNA has transformed recent Eurasian prehistory, while the older, tropical and African chapters remain frustratingly, instructively blank.