A 33,000-year old dog skull was found in a cave in the Altai Mountains of Siberia. This is evidence of early domestication between the human and dog. Paired with an earlier find of an ancient dog skull in Belgium, it indicates that dog have been domesticated by humans throughout history.
Greg Hodgins, a researcher at the University of Arizona’s Accelerator Mass Spectrometry Laboratory and co-author of a study reporting the find said, “Both the Belgian find and the Siberian find are domesticated species based on morphological characteristics. Essentially, wolves have long thin snouts and their teeth are not crowded, and domestication results in this shortening of the snout and widening of the jaws and crowding of the teeth.”
“The Altai Mountain skull is extraordinarily well preserved,” said Greg Hodgins. This allowed the scientists to make measurements of the skull, teeth and mandibles that might not be possible on less well-preserved dog skull remains. He added, “The argument that it is domesticated is pretty solid. What’s interesting is that it doesn’t appear to be an ancestor of modern dogs.”
“The interesting thing is that typically we think of domestication as being cows, sheep and goats, things that produce food through meat or secondary agricultural products such as milk, cheese and wool and things like that,” researcher Greg Hodgins continued. “Those are different relationships than humans may have with dogs. The dogs are not necessarily providing products or meat. They are probably providing protection, companionship and perhaps helping on the hunt. And it’s really interesting that this appears to have happened first out of all human relationships with animals.”
So you might be asking, how do scientists know how old this skull really is without just making up a number? The University of Arizona’s Accelerator Mass Spectrometry Laboratory used radiocarbon dating to determine the age of the Siberian skull. Radioactive carbon, or carbon-14, is one of three carbon isotopes. Humans and animals ingest carbon-14 by eating the plants that have absorbed it through photosynthesis.
“Carbon-14 makes it into all organic molecules,” said Hodgins. “It’s in all living things.”
“We believe that carbon-14 production is essentially constant over time. So the amount of carbon-14 present in living organisms in the past was similar to the levels in living organisms today. When an animal or plant dies, the amount of carbon-14 in its remains drops at a predictable rate, called the radioactive half-life. The half-life of radiocarbon is 5,730 years.”
“People from all over the world send our laboratory samples of organic material that they have dug out of the ground and we measure how much carbon-14 is left in them. Based on that measurement, and knowing the radiocarbon half-life, we calculate how much time must have passed since the samples had the same amount of carbon-14 as plants and animals living today.”
The 33,000-year old dog skull could have been a Siberian skull that predates the Last Glacial Maximum, or LGM, which occurred between about 26,000 and 19,000 years ago. Sheets of ice covered most of North America, northern Europe and Asia in that time. During the Last Glacial Maximum, the Earth’s climate dramatically changed with things like, drought, desertification, and a dramatic drop in sea levels. It was then followed by the Late Glacial Maximum.
Greg Hodgins added, “In terms of human history, before the last glacial maximum people were living with wolves or canid species in widely separated geographical areas of Euro-Asia, and had been living with them long enough that they were actually changing evolutionarily. And then climate change happened, human habitation patterns changed and those relationships with those particular lineages of animals apparently didn’t survive.”