Wolves found food scraps. They ate those. They found the coveted “infinite food glitch.”
That’s how wolves grew closer to prehistoric humans, before eventually getting tamed. However, how did we come from wolves to pugs? How did humans breed them to gain such variety? Most of the credit goes to the breeders of the Victorian era rather than to prehistoric people. However, after analyzing 600 ancient and modern dog skulls, the diversity in dogs appears to have emerged much earlier than the Victorian era. This has been published alongside another article analyzing dog genomes, which provides insight into dog domestication, but isn’t conclusive enough to piece together the origin story of dogs.
To study the origins of dogs, scientists need to identify whether the skulls belong to dogs or wolves, particularly the ones from the last Ice Age. To determine this, bioarchaeologists Allowen Evin, at CNRS University of Montpellier in France, and Carly Ameen, at the University of Exeter, UK, and their team compared three-dimensional scans of the skulls of 643 dogs and wolves that lived in the past 50,000 years. The dog skulls were wider and had shorter snouts than the wolves’. These were first found in an 11,000-year-old specimen in Russia, and earlier work on their genomes revealed that their genomes matched those of modern domesticated dogs. Dog skulls from the late hunter-gatherer and early farming periods revealed an explosion in the variety of dog skulls, from shapes to sizes, accounting for almost half of the varieties present today.
“We often assume that dog diversity emerged since the Victorian period over the last two centuries,” Evin says, “But no — what we found is that from the beginning, there is a huge diversity, much more than what we expected.” However, extreme skull shapes like those of pugs and bulldogs haven’t appeared in the archaeological record and might have been bred later. The reason behind such variety is not yet apparent; however, these might have been early attempts at breeding to produce a dog that would fit the purpose of hunting or companionship perfectly.
The other study found links between human ancestry and their preference toward a dog variety that suited their habitat. By analyzing the genomes of 17 dogs from Central Eurasia and East Asia over the past 10,000 years and comparing them with previously published genomes, this pattern was established.
When the human population migrated, they brought their dogs with them. For instance, the Siberian population preferred Arctic dogs like huskies or sled dogs, but these lineages spread as well. For other groups, the matching ancestry of humans and dogs was absent. This indicated that there was some form of pet trade back in ancient times as well, to get the maximum out of their distinctive features. Arctic dogs have been found in the European Steppes, partnering with hunter-gatherers and with Bronze-working people in China.
Mietje Germonpré, a zooarchaeologist at Royal Belgian Institute of Natural Sciences in Brussels, wonders if this early dog trade stretches even further back in time to the period before the end of the last Ice Age 11,700 years ago, known as the Pleistocene. Genetic analysis suggests that the dog species started to diverge 20,000 years ago.
However, the skulls found from this period did not show convincing signs of domestication, leading to open questions. It is very likely that early dogs had skulls resembling that of wolves, and to gather affirmative evidence, the scientists need to either perform genetic analysis of the skulls, or find more distinctive remains like the lower jaw.
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