The next time you see a Great Dane standing beside a Chihuahua, you are looking at a story that began not in Victorian kennels, but in the distant prehistoric past. A landmark study published in Science and led by the University of Exeter and the French CNRS has 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.
The research team, spanning more than 40 institutions, analyzed 643 modern and archaeological canid skulls using three-dimensional geometric morphometrics — a technique that precisely measures shape and size differences. The specimens ranged from the Pleistocene epoch to the present day, covering 50,000 years of canine history.
Three key findings stand out from the study:
1. Diversity existed long before breed standards. By the Mesolithic and Neolithic periods, dogs already exhibited a wide range of skull shapes and sizes. Early dogs from the Russian site of Veretye (~11,000 years ago), America (~8,500 years ago), and Asia (~7,500 years ago) all showed domestic skull shapes, with significant variation emerging rapidly after domestication.
2. The variation was gradual but substantial. A reduction in skull size first became detectable between 9,700 and 8,700 years ago, while greater variability in skull shape began emerging from around 8,200 years ago. By the Neolithic period, the diversity among dogs was already double that of Pleistocene specimens and had reached half the range seen in modern dogs.
3. No "proto-dogs" found in the Pleistocene. None of the Late Pleistocene specimens — some previously proposed as "proto-dogs" — had skull shapes consistent with domestication. This suggests that the very earliest stages of dog domestication remain hidden from the archaeological record, and the first true dogs continue to elude researchers.
"Diversity among dogs isn't just a product of Victorian breeders, but instead a legacy of thousands of years of coevolution with human societies," said co-lead author Dr. Carly Ameen of Exeter's Department of Archaeology and History. The study suggests that early dog diversity reflected their varied roles in human societies — from hunting and herding to companionship — long before formal breed standards existed.
Modern dogs do exhibit more extreme morphologies, such as the short-faced bulldog and the long-faced borzoi, which are absent in early archaeological specimens. However, the foundation for that diversity was laid thousands of years earlier than previously assumed, shaped by both natural ecological pressures and the profound impact of living alongside humans.