A dog burial in Greene County, Ill. This fossil dates back to about 8,500 years ago.
Credit Courtesy of Del Baston, Center for American Archaeology
This part of a dog skull found in a cave in Belgium dates back to about 36,000 years ago. Scientists think this species was an ancient sister-group to all modern dogs and wolves, rather than a direct ancestor.
Credit Courtesy of Royal Belgian Institute of Natural Sciences
Scientists have used some new tricks and old dogs to show that thousands of years ago, wolves may have first become man's best friend in Europe.
Researchers extracted DNA from ancient wolf or dog fossils and compared it with DNA from modern dog breeds and wolves. Until recently, labs didn't have the kind of genetic tools they'd need to work with such old dog DNA and do this kind of detailed comparison.