If you played golf in Prince George this summer or drove down a country road, you likely encountered a fox or two along the way. These animals inhabit our city making their living by consuming small rodents and other animals. And on the golf courses, getting the occasional hand out from a passing golfer.
That some of the foxes on golf courses are getting quite domesticated is a little worrying but it is a scene which has likely played out several times in human history. Modern dogs are descended from an ancient ancestor resembling a wolf and the relationship probably began in a similar fashion – with handouts and leftovers.
Sometime between 30,000 and 15,000 years ago, humans and the proto-dog met. The first interactions were likely quite wary with some of the dogs stealing food or digging through garbage piles for scraps. But dogs are cute. And at some point, one of our ancestors chose to deliberately feed a whole pack on a regular basis. Our relationship has continued ever since.
Thanks to a recent and extensive study, we now know that by at least 15,000 years ago, those first gray ‘wolves’ had evolved into the dog. Our relationship with dogs has been evolving ever since.
Despite decades of study, scientists still haven’t figured out where domestication began. The most likely scenario is in the Middle East and there is a fair amount of evidence in favour of this view. But in 2019, a study concluded we had domesticated dogs twice – once in Asia and once in Europe or the Near East. While that study has been criticized by some scholars, a more recent research report points to signs of domesticated dogs in the Americas as early as 10,000 years ago. However, those canines now appear to have vanished with few genetic traces remaining. Other studies provide evidence of the deliberate breeding of sled dogs in Siberia 9,500 years ago but how the dog got there is still unknown let alone its lineage.
To fill in the blanks in the evolutionary history of the dog, Greger Larson, an evolutionary biologist at the University of Oxford, Pontus Skoglund, a paleogenomicist at the Francis Crick Institute, and archeologist Ron Pinhasi at the University of Vienna teamed up to sift through more than 2,000 sets of ancient dog remains covering the period from 11,000 to 100 years ago.
The result was the addition of 27 new ancient dog genomes to the existing record of only six ancient dog or wolf genomes. They then linked these ancient dog genomes to 17 humans living in the same places and times as the dogs.
They have been able to show that by 11,000 years ago, dogs had already diverged into five different lineages and had spread worldwide. These lineages gave rise to canines in the Near East, northern Europe, Siberia, New Guinea, and the Americas. Because domestication and genetic diversification take a long time, this fits with the archeological evidence for the oldest definitive dog remains, which are 15,000 to 16,000 years old and come from Germany.
Ironically, while the genetic diversity of these early dogs allows the scientists to piece together ancient lineages (Chihuahuas can trace their ancestry back to early American dogs, for example), modern dogs show much less genetic diversification. All European dogs can be traced to a single group of ancient pooches. The modern diversity of dog shapes and sizes arise from bred in traits as opposed to fundamental genetic differences. Yes, a Chihuahua could mate with a Great Dane.
What was surprising from the data is the absence of wolf DNA in modern breeds. Most domesticated animals pick up genetic material from their wild cousins through occasional interbreeding. But comparing both modern and ancient wolf DNA with ancient dog genomes, there is no apparent gene flow from wolves to dogs although flow appeared to occur in the other direction.
Larson chalks this up to the intimate relationship we have with dogs. If you are a dog and slightly feral or prone to attacking humans because of some wolf in you, you won’t last long. People get rid of troublesome animals.
But the wolf-dog analysis also suggests dogs evolved only once from an original wolf population. Once the proto-dog had started on the path to domestication, it disappeared from the fossil wolf record. The shift was a one-way street.
Throwing humans into the mix provides evidence dogs moved with some human population, such as Siberian nomads, but not with others, such as farmers occupying what is now modern Germany 7,000 years ago. In the latter case, while the farmers arrived from the Near East, their pets came from Siberia.
Our relationship with the dog is likely the oldest and strongest we have. And for those of us who are dog lovers, it is one for which we are thankful.