Domestic dogs: Diversity emerged thousands of years before modern breeding

A groundbreaking archaeozoological study has revealed when domestic dogs first began to show the remarkable diversity that characterises them today. By applying modern shape analysis to hundreds of archaeological specimens spanning tens of thousands of years, researchers have traced the emergence of distinct dog forms deep into prehistory pinpointing the moment dogs began to diversify in size and shape - at least 11,000 years ago.

These findings challenge long-standing assumptions that canine diversity is largely a recent phenomenon shaped by selective breeding which started with the Victorian Kennel Clubs in the 19th century. Instead, the study demonstrates that significant variation in skull shape and size among domestic dogs was already present thousands of years ago, soon after their divergence from wolves.

Since the project began in 2012, 643 skulls of modern and archaeological canids have been recorded for the study, including recognized dog breeds, street dogs, and wolves. The samples cover a period of 50,000 years, from the Pleistocene to the present day, as well as a large geographical area. The comprehensive data collection also includes material from Switzerland: around 60 dog skulls from the globally unique cynological collection of the Natural History Museum in Bern were included in the analysis. These include modern breeds such as St. Bernards and Bernese Mountain Dogs, as well as Neolithic and Bronze Age dogs from pile dwelling settlements. “Prehistoric dogs from the Swiss Plateau show a variability that is found today in medium-sized dogs with a so-called mesocephalic head shape – such as Border Collies or large and medium-sized Spitz dogs,” says André Rehazek, curator of archaeozoology at the Natural History Museum in Bern.

A team of researchers from over 40 institutions analyzed the skulls. Their conclusion: dogs of various sizes and shapes already existed in the Mesolithic and Neolithic periods – presumably in response to their different roles in early societies, such as hunting, livestock farming, or social bonding. The earliest specimen identified as a domestic dog came from the Russian Mesolithic site of Veretye (dating to ~11,000 years ago). The team also identified early dogs from America (~8,500 years ago) and Asia (~7,500 years ago) with domestic skull shapes. After that, the study shows a lot of variation emerging relatively quickly.

The study also underscores the challenges of tracing the earliest dogs. None of the Late Pleistocene specimens - some previously proposed as “proto-dogs” - had skull shapes consistent with domestication, suggesting that the very first stages of the process remain difficult to capture in the archaeological record. The researchers note: “The earliest phases of dog domestication are still hidden from view and the first dogs continue to elude us. But what we can now show with confidence is that once dogs emerged, they diversified rapidly.”