An Ice Age Gave Dog Domestication the Cold Shoulder
Regarded as “mans best friend” dogs have had an extraordinary relationship with humans and as a result can be regarded as one of the most successful types of mammal on the planet. A new study suggests that mankind’s close relationship with dogs began as early as 33,000 years ago. However, an Ice Age that started approximately 26,000 years ago; which resulted in dramatically changing climatic conditions over much of the Northern Hemisphere interrupted this domestication process. It was not until the climate became milder and more stable some 7,000 years later did the dog/mankind relationship start up again in earnest.
In a new study published in the online scientific journal PLoS ONE (Public Library of Science) researchers claim that although dogs had started to become domesticated at least 33,000 years ago, these canines did not produce descendants that survived beyond the Ice Age.
The theory, based on the analysis of the 33,000-year-old remains of a dog that may have been a partly domesticated, explains why the remains of possible prehistoric dogs date to such early periods, and yet all modern dogs appear to be descended from ancestors that lived at the end of the Ice Age 17,000-14,000 years ago. How and why creatures such as wolves began to associate with people has been the subject of debate for a long time. In Darwin’s time it was thought that domesticated dogs originated from a number of wild stocks, however, modern genetics indicates that all dogs today can trace their ancestry back to the wolf. Wolves and humans have a surprising amount in common, especially when their roles as predators are considered. For example, humans and wolves hunt in daylight, both are social creatures and use vision as an important sense when attacking prey. They also preyed on the same types of animal – the mega herbivores as they are known. It is likely that wolves began to associate with humans getting scraps from kills and slowly but surely the path towards domestication began to be taken.
The 33,000 doggy remains were found in a cave in the Altai Mountains of southern Siberia (Razboinichya cave). It was found amongst other wild animal bones but was the only dog-like creature found.
Susan Crockford, co-author of the study stated:
“The Razboinichya dog find demonstrates that the right wolf/human conditions suitable for getting domestication started were present at least 33,000 years ago. However, such conditions would have had to be present continuously [stable climatic conditions] for many wolf generations, for the domestication process to generate a true dog.”
An on-going Russian study into foxes has been testing how quickly wild animals can become domesticated. The study has been operating for many years, with each generation of fox cubs selected for tameness, with these animals being allowed to breed with other foxes that although show a degree of domestication. Over many generations of foxes the Russian scientists have been able to produce a fox that behaves in a very similar way to domesticated dogs.
Susan Crockford, a researcher at Pacific Identifications Inc. added:
“It appears that such stable conditions were not present until after the Ice Age, sometime after 19,000 years ago,. Even after the Ice Age, domestication of wolves could have got started at several different times and places, and still failed because the conditions were not continuous enough for the changes to become permanent.”
The Siberian animal was unearthed some years ago, but was only recently dated to 33,000 years ago by three independent radiocarbon dating facilities. Crockford and her colleagues conclude that it was a partly domesticated dog because of its mixture of dog and wolf features. It was about the size and shape of a large male Samoyed dog, so it was smaller than a European wolf, but its teeth were still wolf-sized. The scientists have concluded that it “probably behaved more like a wolf than a dog.”
Its remains were excavated from a cave area containing wild animal bones. Usually fully domesticated dogs, even very early ones, received more careful burials, often being placed in graves with, or next to, their owners. In fact, a recent discovery may indicate that the fox Vulpes vulpes may have been early man’s best friend.
To read an article about the discovery of a fox buried with humans in a Mesolithic grave: Is the Fox Man’s Best Friend?
Since no other dog-like animals were found at the site, the researchers think this animal was an “incipient” dog in the early stages of domestication. The scientists hold that domestication can happen naturally, without direct human intervention, when wolves are attracted to settlements and gradually adjust to a human-dependent lifestyle, relying on people for scraps of food and such like. Certainly, if a wolf-like animal could be domesticated it would have had tremendous benefits for people. These dogs could have acted as watch dogs, helping to keep people safe from other wild animals, they could have assisted in hunting and, for anyone who has had a dog curl up on their feet, as wolves have a higher body temperature than humans they would have been very good at keeping us warm at night.
The Ice Age, however, changed the abundance and migration patterns of the animals that the people in the Altai Mountains of Siberia hunted for food. The researchers conclude that with the climate change, people would have been more nomadic and this would have interrupted any domestication of wolves.
Without the conditions that fuel domestication, the dog or dog-like animals gradually died off, the researchers suspect. Dogs reemerged after the Ice Age, reproducing and becoming the ancestors to today’s modern dogs. It is unclear when the first pre-Ice Age dogs emerged, but a dog-like skull dating to 36,500 years ago was found at Goyet Cave in Belgium. It’s possible then that the first dogs appeared in parts of Europe and Asia much earlier than commonly thought. Many scientists do believe that the wolf was the first animal to be domesticated by mankind, and may partially explain why dogs and humans have such a special relationship, indeed dogs do seem to have developed some unique ways of understanding our moods and communicating with us. After all, it is now thought that the dog “bark” was adopted by dogs so that they could communicate with humans – wolves don’t bark as a rule.
Other scientists have queried these research results and have suggested that more fossil specimens will be needed to prove conclusively the theory postulated by Susan Crockford and her colleagues. Without more specimens, it cannot be ruled out that the Siberian dog, and possibly some of the other pre-Ice Age animals, were different representatives of now-extinct wolves.
Richard Meadow, director of the Zooarchaeology Laboratory at Harvard University’s Peabody Museum, expressed his reservations about the study’s conclusions.
Crockford admits that the paper presents “a new way of thinking about domestication, but it fits the evidence better than the idea that people deliberately created dogs for some specific purpose.”
We await to see what lies lurking in the depths of the caves of the Altai Mountains, perhaps an ancient dog collar or maybe a rubber bone anyone?
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