When your cute little doggo is gazing up at you with its innocent puppy eyes, wagging its tail in the hope you’ll throw its tennis ball just one more time, it’s hard to believe that its ancestors were large, toothy, night-dwelling wolves that took down beasts the size of bison in strategically formed groups. It’s clear that since dogs began to be domesticated over 10,000 years ago, a great deal has changed, so what really does make dogs man’s best friend?
Well, a team of researchers took it upon themselves to find out, publishing their findings in BMC Biology. Somewhere between 10,000 and 40,000 years ago, humans started to domesticate wolves in Eurasia, making them not only man's best friend, but man's oldest animal friend too.
The researchers compared the DNA of wolves, the remains of dogs buried 5,000 years ago, and village dogs. Village dogs account for two-thirds of the world’s dogs – they roam, scavenge for food near human populations, and can mate freely. Village dogs were used because pedigree dogs’ genes have been messed about with by people over the last 300 years to give them desired characteristics like fluffy coats and curly tails, which could have affected the results.
"We convinced ourselves that previous studies found many genes not associated with being a dog but with being a breed dog," said lead author Amanda Pendleton.
The researchers identified 246 gene regions associated with domestication. They found that these particular genes influence things like behavior, brain function, and development. What's more, the findings support the neural crest hypothesis, which scientists often use to explain the development of features of domestic animals not seen in their wild counterparts.
"The neural crest hypothesis posits that the [physical characteristics] we see in domesticated animals over and over again – floppy ears, changes to the jaw, coloration, tame behaviour – can be explained by genetic changes that act in a certain type of cell during development called neural crest cells, which are incredibly important and contribute to all kinds of adult tissues," Pendleton explained.
Changes in these neural crest cells to produce tame behavior appeared first, before giving rise to the more physical features of domestic dogs, like a shorter snout and cute floppy ears. Therefore, behavior was the first thing to change on dogs’ journey to becoming man’s best friend, and their cuddly appearances popped up later. So, back in the day, our ancestors' furry companions were a lot friendlier than they looked.