Dogs are twice as friendly to humankind as previously thought, suggests study

Study raises possibility that two populations of grey wolves, separated by thousands of miles and years, may have resulted in modern domestic dogs

Humankind's long friendship with the dog may have begun at least twice. Grey wolves in western Eurasia may have started hanging around Stone Age hunter-gatherer clans even before humans and dogs clinched the relationship perhaps 14,000 years ago in east Asia.

New research based on DNA samples from prehistoric hounds, as well as genetic studies of modern dogs and wolves, suggests that two populations of grey wolves - separated by thousands of miles and thousands of years - may have begun the connection that turned Canis lupus into Canis lupus familiaris.