Humans and dogs: it’s one of the most successful and enduring evolutionary partnerships in history and one that has figuratively helped shaped humanity and literally shaped dogs. From their wolf ancestors, dogs have diversified into an incredible array of shapes and sizes.
Surprisingly, perhaps, new studies suggest that the diversification began remarkably early.
When, exactly, humans and dogs partnered up is unknown, but is thought to have been anywhere between 15,000 and 30,000 years ago. One new study of ancient dog genomes has found that dogs were migrating across Eurasia alongside early humans at least 10,000 years ago. A second study examined hundreds of dog and wolf skulls, to try to determine when dog diversity emerged.
Allowen Evin, a bioarchaeologist at CNRS University of Montpellier in France, spoke with Nature about the results of the dog skull study. “We often assume that dog diversity emerged since the Victorian period over the last two centuries,” said Evin. “But no – what we found is that from the beginning, there is a huge diversity, much more than what we expected.”
Evin’s research took a look at 3D scans of the skulls of 643 dogs and wolves that lived over the past 50,000 years. The team identified a distinctive dog skull shape – with a shorter snout and wider face than wolves – that first appeared in fossils from northwest Russia that date back nearly 11,000 years.
This was, as it happens, roughly the same time as the “Neolithic explosion” that saw the beginnings of the first settled, complex, agrarian societies. It also coincided with an explosion in dog skull shapes and sizes, accounting for more than half of the diversity in today’s breeds. Humans were still some way from breeding pugs, but a long way from domesticated wolves.
This early diversity likely reflects deliberate breeding efforts as humans adapted dogs for specific purposes, including hunting, protection, and companionship, the researchers said. This desire to breed certain traits into canines was evidenced in the second study, too – this time through DNA […]
Carly Ameen, a bioarchaeologist at the University of Exeter who co-authored the study, told NPR […“Very] early on in our relationship with dogs, we not only change them from wolves, but they begin to change among themselves and generate a lot of diversity.”
Analysis of 73 ancient dog genomes, within the last 10,000 years, found that different human ancestries tended to be associated with regionally distinct dog populations. For example, ancestry from ancient people in northeastern Siberia was linked to Arctic dogs, whose descendants include modern huskies and sled dogs.
In some cases, however, disconnects between human and dog ancestries in certain populations suggest that canines were traded between civilizations, likely to bring out specific traits in working animals. Laurent Frantz, a population geneticist at Ludwig Maximilians University in Munich who co-led the genome study, noted that dogs with Arctic ancestry proved especially popular, appearing with hunter-gatherers on the Eurasian Steppe and later with Bronze Age populations in southern China.
The research also leads to one inevitable conclusion: human domestication of wolves happened long before 11,000 years ago. Even the earliest samples of known dogs are distinctly different from wolves.
“[B]y 11,000 years, you already had dogs all the way in Siberia and in Europe for thousands of years, probably… long enough for them to become different,” said Frantz. “So we’re looking at a time where everybody had dogs already” […]
Genome studies suggest the main dog lineages began diverging around 20,000 years ago during the Pleistocene period, but confirmed dog fossils from that era remain elusive. None of the 17 Pleistocene skulls analyzed in the new research, for example, showed signs of domestication.
Which might also show the limits of morphology as a guide to when canine domestication occurred. Other important changes were purely internal, such as the ability of dogs to digest starch, which wolves cannot. This almost certainly evolved as a result of living alongside human companions who were transitioning from a meat-heavy hunter-gatherer lifestyle to a settled, agricultural one.
*‘Slipper dog’: that annoying little yapping shit you kick up the arse and wear like a slipper.
