Ancient Dog Skulls Challenge Views on Canine Evolution

New research has uncovered significant evidence indicating that dogs began diversifying in size and shape far earlier than previously believed. A comprehensive study involving over 600 ancient dog skulls reveals that these early canines were adapting to various roles within human societies as far back as 11,000 years ago. This finding challenges the long-held notion that dog diversity primarily stemmed from recent selective breeding practices.

The study, published in the journal *Science*, was led by researchers from the University of Exeter in collaboration with the French CNRS. It represents the most extensive analysis of dog skulls to date, examining specimens that span approximately 50,000 years, from the Pleistocene epoch to modern times. This global research, which began in 2014, utilized advanced 3D modeling and geometric morphometrics, enabling scientists to make precise comparisons between different skull shapes and sizes.

Uncovering Early Canine Diversity

The analysis indicates that by the Mesolithic and Neolithic periods, dogs exhibited a wide range of physical forms. This diversity likely reflected the various roles they played in early human communities, including hunting, herding, and companionship. Co-lead author Dr. Carly Ameen from Exeter’s Department of Archaeology and History remarked, “These results highlight the deep history of our relationship with dogs. Diversity among dogs isn’t just a product of Victorian breeders but instead a legacy of thousands of years of coevolution with human societies.”

The oldest confirmed domestic dog identified in the study came from the Russian Mesolithic site of Veretye, dating back to approximately 11,000 years ago. Additionally, researchers found evidence of early domestic dogs in the Americas and Asia, dating around 8,500 and 7,500 years ago, respectively. Dr. Allowen Evin, another co-lead author from the CNRS, explained, “A reduction in skull size for dogs is first detectable between 9,700 and 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.”

Insights into Dog Domestication

The findings from this study have significant implications for understanding the domestication process. Despite examining numerous specimens from the Late Pleistocene, researchers did not find any skull features indicative of domestication. This suggests that the earliest stages of dog domestication remain elusive in the archaeological record. Professor Greger Larson from the University of Oxford emphasized, “The earliest phases of dog domestication are still hidden from view, and the first dogs continue to elude us.”

The research reveals that once dogs emerged as a distinct species, they diversified rapidly. This early variation reflects not only natural ecological pressures but also the profound influence of living alongside humans. Modern dogs display a wide array of physical traits, such as the short-faced bulldogs and long-faced borzois, which were not present among early archaeological specimens. The diversity observed in Neolithic dogs was already double that of Pleistocene specimens and about half of what is seen in dogs today.

By establishing that dog diversity emerged thousands of years earlier than previously assumed, this study offers new perspectives on how human culture and environmental changes influenced the evolution of our canine companions. The insights gained reinforce the idea that dogs and humans have shared a close relationship since the very beginnings of domestication.

Funding for this research was supported by multiple national and international agencies, including the Natural Environment Research Council (UK), the Arts and Humanities Research Council (UK), the European Research Council, the Social Sciences and Humanities Research Council of Canada, the Russian Academy of Sciences, and the Fyssen Foundation.