It turns out that today's dog breeds may not have evolved from the gray wolf, at least not the kind of gray wolf that exists today.
A study in the current issue of PLoS Genetics suggests that, instead, dogs and gray wolves share a common ancestor in an extinct wolf lineage that lived thousands of years ago.
An international team of researchers generated genome sequences from three gray wolves – one each from China, Croatia, and Israel, the three countries where dogs are believed to have originated. They then sequenced the genome of a basenji dog from central Africa and a dingo from Australia. Both the regions have been historically isolated from wolf populations, according to a press release by The University of Chicago Medical Center.
Analysis of these genomes from the wolves and the dogs showed that the dogs were more closely related to each other than they were to the wolves. The wolves, too, were closely related to each other than to the dogs.
Additionally, the scientists did not see a clear evidence linking dogs to any of the living wolves that were sampled.
"One possibility is there may have been other wolf lineages that these dogs diverged from that then went extinct," said John Novembre, associate professor in the Department of Human Genetics at the University of Chicago and a senior author on the study.
This shakes up the popular belief on domestication of dogs that are considered to be these "few docile, friendly wolves" which later became dogs after they were adopted by early farmers. Instead, the earliest dogs might have started out among hunter-gatherers before adjusting to an agricultural life later, Adam Freedman, a postdoctoral fellow at the University of California, Los Angeles (UCLA) and the lead author on the study, told the Monitor.
There does exist some amount of genetic overlap between some modern dogs and wolves. But this is thought to be the result of interbreeding after dogs were domesticated, not a direct line of descent from one group of wolves, according to the press release.
"If you don't explicitly consider such exchanges, these admixture events get confounded with shared ancestry," he said. Admixtures are hybrids produced due to interbreeding between two different population groups. "Dog domestication is more complex than we originally thought," said Dr.Novembre.
This findings, says Dr. Freedman, will help them to study the genes involved in making dogs more dog like, and understand the history of evolution among the canines "We're trying to get every thread of evidence we can to reconstruct the past," Novembre said. "We use genetics to reconstruct the history of population sizes, relationships among populations and the gene flow that occurred. So now we have a much more detailed picture than existed before, and it's a somewhat surprising picture."