New research reveals that domestic dogs began developing diverse sizes and shapes over 11,000 years ago, far earlier than previously thought. A comprehensive analysis of ancient canid remains challenges the notion that modern dog breeds stem mainly from recent selective breeding. Instead, it highlights a long history of coevolution between humans and canines.
Archaeological findings are rewriting the timeline of dog domestication. Scientists analyzed 643 canid skulls from modern breeds, street dogs, wolves, and ancient sites, spanning about 50,000 years from the Pleistocene era to today. The project, which started in 2014, involved researchers from over 40 institutions, including the University of Exeter and the French CNRS. They created 3D models and applied geometric morphometrics to compare skull sizes and shapes precisely.
The study, published in Science, identifies the oldest confirmed domestic dog at the Russian Mesolithic site of Veretye, dating back approximately 11,000 years. Similar early domestic dogs appeared in America around 8,500 years ago and in Asia about 7,500 years ago. Key changes emerged soon after: skull size reduction between 9,700 and 8,700 years ago, increased size variance from 7,700 years ago, and greater shape variability starting around 8,200 years ago.
By the Mesolithic and Neolithic periods, dogs exhibited a wide array of skull forms and body sizes, likely adapting to roles such as hunting, herding, guarding, and companionship in human societies. This diversity was double that of Pleistocene specimens and half of what is seen in modern dogs, though extreme forms like short-faced bulldogs were absent in early remains.
"These results highlight the deep history of our relationship with dogs," said Dr. Carly Ameen of Exeter's Department of Archaeology and History. "Diversity among dogs isn't just a product of Victorian breeders, but instead a legacy of thousands of years of coevolution with human societies."
Dr. Allowen Evin from the CNRS added: "A reduction in skull size for dogs is first detectable between 9,700-8,700 years ago, while an increase in size variance appears from 7,700 years ago. Greater variability in skull shape begins to emerge from around 8,200 years ago onwards."
None of the Late Pleistocene skulls showed domestication traits, underscoring the challenge of pinpointing the very start of the process. Professor Greger Larson of the University of Oxford noted: "The earliest phases of dog domestication are still hidden from view... But what we can now show with confidence is that once dogs emerged, they diversified rapidly. Their early variation reflects both natural ecological pressures and the profound impact of living alongside humans."
Funded by agencies like the Natural Environment Research Council and the European Research Council, the work suggests human cultural and environmental shifts influenced canine evolution from the outset.
