Mitochondrial DNA passes from mother to child. In a community where women stay and men move in, the mitochondrial lineages converge. After a few generations, most members share a small number of maternal lines. In a community where men stay and women move in, the mitochondrial pool is diverse — each incoming woman brings a different lineage from a different origin.
Cassidy and colleagues analyzed 57 genomes from Iron Age Dorset burial sites — the Durotrigian communities of southern England between 100 BC and AD 100. Twenty-four of the thirty-four identified relatives shared a single mitochondrial lineage that occurs at a frequency of 0.00003% in modern populations. The unrelated burials were predominantly male. Women belonged. Men arrived.
The pattern held beyond Dorset. Multiple Iron Age British sites showed the same signature: extremely low mitochondrial diversity. Worlebury in Somerset, Gravelly Guy in Oxfordshire, Trethellan Farm and Tregunnel in Cornwall, Pocklington in Yorkshire. The matrilocal structure wasn't a regional anomaly — it was a widespread social organization visible only through genetic data.
The grave goods don't tell this story. The burial positions don't tell it. The artifacts — brooches, weapons, pottery — encode status and trade networks, not residence rules. Archaeologists looking at objects would see a mixed community. Geneticists looking at mitochondria see a community organized around maternal continuity, in which social belonging was defined by the maternal line and men were the mobile component.
Diversity usually signals vitality — genetic richness, cultural exchange, open borders. In maternal lineages, the opposite is true. Low mitochondrial diversity doesn't mean genetic poverty. It means the women stayed, generation after generation, and the community formed around them. The low count is the evidence of who held the center.