In the 1950s, Belyaev and his team spent years breeding the silver fox (Vulpes vulpes) and selecting only those that showed the least fear of humans.
After about ten generations of controlled breeding, the domesticated silver foxes no longer showed any fear of humans and often wagged their tails and licked their human caretakers to show affection. They also started to have spotted coats, floppy ears, and curled tails.
As a result of domestication, the adrenaline levels of the domesticated foxes were significantly lower than normal. The presence of their multicolor coats is theorized by the scientists to be related to changes in melanin, which controls pigment production and shares a biochemical pathway with adrenaline. It could also be that it was a result of hormonal changes that occurred as the foxes became increasingly tame.
The changes to the foxes’ coats as they became domesticated may have helped solve the biological riddle of how dogs evolved to have coats different from wolves.
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