Dog Skull Analysis Rewrites Evolution of Humanity’s Best Friend

A surprising diversity of dog shapes and sizes evolved long before the Victorians began making modern breeds

By Kate Wong edited by Clara Moskowitz

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Modern dog breeds come in a mind-boggling array of shapes and sizes—from Chihuahua to Great Dane, corgi to greyhound, pug to German shepherd. In fact, the domestic dog, Canis familiaris, shows more variation in its physical features than any other mammalian species on Earth. Conventional wisdom holds that this extreme variation is the result of humans intensively breeding dogs for particular traits over the past 200 years or so. Now a new analysis of modern and ancient dog and wolf skulls has upended this idea, revealing a far earlier origin for dog diversity.

In the new study, Allowen Evin of the University of Montpellier in France and her colleagues analyzed hundreds of dog and wolf skulls that spanned the past 50,000 years. The oldest skull in their sample with definitive dog traits dated to nearly 11,000 years ago, which aligned with DNA estimates of when dogs evolved from wolves. What’s surprising is that the researchers found a substantial degree of diversity in the sizes and shapes of dog skulls among the earliest specimens they studied. Although these features didn’t reach the extremes seen in modern breeds, such as bulldogs, with their smushed face, and borzois, with their ultralong snout, these ancient dogs exhibited fully half the diversity of modern dogs—a lot more than expected.

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The findings indicate that humans were not the sole driver of dog evolution, as previously thought. Other factors, such as climate or geography, might have contributed significantly to making humanity’s best friend the extraordinarily diverse species that it is today.

Kate Wong is an award-winning science writer and senior editor for features at Scientific American, where she has focused on evolution, ecology, anthropology, archaeology, paleontology and animal behavior. She is fascinated by human origins, which she has covered for nearly 30 years. Recently she has become obsessed with birds. Her reporting has taken her to caves in France and Croatia that Neandertals once called home to the shores of Kenya’s Lake Turkana in search of the oldest stone tools in the world, as well as to Madagascar on an expedition to unearth ancient mammals and dinosaurs, the icy waters of Antarctica, where humpback whales feast on krill, and a “Big Day” race around the state of Connecticut to find as many bird species as possible in 24 hours. Wong is co-author, with Donald Johanson, of Lucy’s Legacy: The Quest for Human Origins. She holds a bachelor of science degree in biological anthropology and zoology from the University of Michigan. Follow her on Bluesky @katewong.bsky.social

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