Critically, the ancestry analysis also illuminated what happened after Cheddar Man’s time. The Western Hunter-Gatherers of Mesolithic Britain did not give rise, in a simple uninterrupted line, to modern British people. What the ancient DNA evidence shows — most clearly from the 2019 paper in Nature Ecology and Evolution by Brace, Diekmann, Booth, and their colleagues, which included Cheddar Man’s genome among a broader dataset — is that the Mesolithic population of Britain was largely replaced by incoming Neolithic farmers around 4000 BCE.
These farmers were genetically distinct from the Western Hunter-Gatherers. They were descended primarily from populations originating in the Aegean region — western Anatolia and the Aegean islands — and they had spread through Europe along Mediterranean and Danubian routes before arriving in Britain. When they arrived, the genetic picture of Britain changed substantially. The hunter-gatherer ancestry did not disappear entirely, but it was diluted to the point where, as the Natural History Museum has noted, only about ten percent of modern British ancestry is attributable to western European Mesolithic hunter-gatherers — and that ten percent is understood to represent ancestry from the entire Western Hunter-Gatherer population, dispersed across Europe, rather than specifically from the Cheddar Man population in Britain.
This is an important point that some early media coverage of the 2018 announcement handled imprecisely. Claims that modern Britons “can trace ten percent of their ancestry” to Cheddar Man specifically, or that Cheddar Man is an ancestor of all modern British people, overstate what the genetics can establish. The ten percent figure describes a population-level proportion, and the ancestry it represents came primarily through later migrations that included people already genetically mixed with Western Hunter-Gatherers on the continent — not directly from the Mesolithic population of Britain.