Molecular Medicine Israel

How dogs became humans’ best friends: from Neanderthals to now

A lively tale of evolution, domestication, migration and fellowship.

Our Oldest Companions: The Story of the First Dogs Pat Shipman Belknap (2021)

Several years ago, strolling through Washington Square Park in New York City, I found myself surrounded by hundreds of dachshunds with their human partners. Some were even dressed as hot dogs. I had stumbled on Dachshund Day, an annual event.

Short-legged and long-bodied, the dachshund seems eons away in shape and lifestyle from its ancestor, the grey wolf (Canis lupus). Yet domestic dogs differ from their wild forebears by, at most, 0.2% of their mitochondrial DNA sequence. So relates palaeoanthropologist Pat Shipman in her lively tale of dog domestication and migration, Our Oldest Companions.

Unlike wolves, dachshunds — originally bred in Germany to hunt badgers — are keen to be part of, and communicate with, a group that includes humans. All domesticated dogs exhibit such traits: they are our companions, protectors, playmates, herders, blankets and hunting aids, Shipman writes.

Dogs were the earliest animal to be domesticated. But when and why did they become our fellow travellers? That question is at the heart of Shipman’s narrative, a round-the-world and back-in-time journey to the era when Homo sapiens first encountered Neanderthals in ice-age Europe, one of the most likely locales for early dog domestication. Neanderthals never domesticated dogs, but they did hunt the same animals as European wolves, mostly medium- to large-sized herbivores, including deer.

When Homo sapiens, travelling out of Africa, reached Europe between 50,000 and 40,000 years ago, they encountered — and bred with — Neanderthals. Homo sapiens gained the advantage, Shipman claims, by forging a “long-term, mutually beneficial partnership with canids” to hunt bigger prey, which might have helped to drive the extinction of Neanderthals. She concedes that not everyone agrees with this hypothesis.

Skill share

By cooperating with dogs, and living intimately with them, humans were able to capitalize on the animals’ abilities, “such as a keen sense of smell, the stamina to run swiftly and nearly tirelessly after potential prey, and good eyesight”, Shipman writes. She hypothesizes that, perhaps 36,000 years ago, animals that she calls wolf-dogs — not yet fully resembling modern dogs, but no longer wolves — became our companions. The collaboration offered mutual benefits: wolf-dogs could find, surround and hold a mammoth until humans could spear it; humans could protect wolf-dogs from local, wild wolf packs.

Mietje Germonpré, an archaeozoologist at the Royal Belgian Institute of Natural Sciences in Brussels, has found skulls, jaws and sharp teeth of canids at archaeological sites in Belgium, the Czech Republic and Russia that date to as far back as 36,000 years ago. But such dates for domestication are highly contested, and these “protodogs” might represent subspecies of the grey wolf. A period around 16,000 years ago is the more widely accepted time frame for dog domestication. However, “there is no single anatomical trait that can distinguish a dog from a wolf with certainty”, Shipman writes.

Instead, researchers rely on subtle variations in mitochondrial DNA, dietary changes (detected in ancient bones) and cultural shifts, such as the burial of dogs alongside humans, most famously at the 14,000-year-old site of Bonn-Oberkassel in Germany. In 2018, analysis of a tooth found in the grave indicated that humans had cared for a sick puppy for weeks before it died (L. Janssens et al. J. Archaeol. Sci92, 126–138; 2018).

There are some mysterious gaps in the narrative. By at least 55,000 years ago, the first Australians had navigated open seas in boats to reach the super-continent of Sahul, or Greater Australia (comprising Australia, New Guinea and Tasmania, which were one land mass when sea levels were lower). These travellers were dogless. Instead of partnering with canids to pursue prey, Shipman posits, they fished and gathered shellfish, or hunted small marsupial animals and birds so fearless of humans that they were easy to capture. Dingoes were brought to Australia by boat about 5,000 years ago, after which Indigenous Australians did form bonds with them. They raised dingo pups as pets and treated them as companions and guardians against humans or supernatural beings.

Global range

None of the earliest Americans, who migrated to North America from Siberia across the land mass of Beringia, were associated with canids, either. An 18,000-year-old puppy, dubbed Dogor (‘friend’ in the Yakut language), that emerged from melting Siberian permafrost in 2018 could have been an ancestor of dogs or wolves. But the earliest trace of a dog in North America, a fragment of femur from Alaska, is just 10,000 years old.

The Mexican Chihuahua might be descended directly from dogs that lived in the region before the arrival of Europeans, but in South America, wild canines such as the rare bush dog (Speothos venaticus) remained untamed. Horrifyingly, conquistadors trained Spanish mastiffs to chase and kill Indigenous peoples of South America. Yet Shipman writes that Indigenous peoples later eagerly adopted European dogs and formed close bonds with them.

As I followed Shipman on her journey, I began to understand why the fellowship of dachshunds — or poodles or pugs or chihuahuas — is one of partnership, not ownership. The companionship of dogs has been shown to ameliorate mental and physical disabilities, and reduce anxiety associated with ageing, loneliness, autism and post-traumatic stress disorder. Perhaps, as Shipman concludes, that is because dogs’ friendship and protection have helped us to survive and thrive, together, for millennia.

Nature 599, 553-554 (2021)

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