The Ancestors Who Left Nothing
Essay · biology · September 2026 Thirty generations back you have a billion slots in your family tree and about two thousand pieces of DNA to fill them with. Everyone of European descent is descended from Charlemagne; almost no one carries anything of his. Ancestry runs on two clocks, one exponential and one linear, and the gap between them is where genealogy and genetics part company — and where the newest object in population genetics, a graph that holds the whole history of a species’ DNA, comes in.