If you think a Chihuahua doesn't have much in common with a Rottweiler, you might be on to something.
An ancient dog skull, preserved in a cave in the Altai Mountains of Siberia for 33,000 years, presents some of the oldest known evidence of dog domestication and, together with equally ancient dog remains from a cave in Belgium, indicates that domestication of dogs may have occurred repeatedly in different geographic locations rather than with a single domestication event.
In other words, man's best friends may have originated from more than one ancient ancestor, contrary to what some DNA evidence previously has indicated.
"Both the Belgian find and the Siberian find are domesticated species based on morphological characteristics," said Greg Hodgins, a researcher at the University of Arizona's Accelerator Mass Spectrometry Laboratory and co-author of the study that reports the find.
"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 Hodgins, enabling scientists to make multiple measurements of the skull, teeth and mandibles that might not be possible on less well-preserved remains. "The argument that it is domesticated is pretty solid," said Hodgins. "What's interesting is that it doesn't appear to be an ancestor of modern dogs."
The UA'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. Along with naturally occurring carbon dioxide, carbon-14 reaches the surface of the Earth by atmospheric circulation, where plants absorb it into their tissues through photosynthesis.
Animals and humans take in carbon-14 by ingesting plants or other animals that have eaten plants. "Carb
|Contact: Daniel Stolte|
University of Arizona