Danelaw

• Such words have their origins in migrations and conquests that took place during the Middle Ages.
• Cultural evolution researchers like us know that it’s not just mountain ranges or oceans that can be barriers to interaction.
• This can be seen most clearly when cultural traditions lead people to marry people from the same community.
• Can smaller things, like the different dialects between neighboring villages, shape the genetic landscape of populations?

Combining two sets of data

• Ideally, we could use a unified data set capturing information about the genetics and dialects of people living in a region.
• Instead, we used data from two separate studies that focused on people from approximately the same time and place.
• For linguistic data, we relied on the Survey of English Dialects.
• Over time, dialects can persist in similar locations if geographic or cultural barriers influence how often and with whom people interact.

The echo of sounds long gone

• Our results suggest that language, or some other aspect of culture, has limited how people interacted to some degree over the past thousand years.
• This is the first time that information about linguistic dialects has been compared with modern genetic data within a population, particularly at such a granular level.
• Notably, people speaking different dialects have no obvious reason to avoid marrying one another, as would be expected from groups with specific marriage customs.
• At the same time, immigrants from the former British Empire and elsewhere have brought a new influx of language.