Evolution in Action: The Silver Fox Experiment

An experiment running for 50 years in Russia demonstrates how how the wolves could have been domesticated into dogs. In just a few decades, while selecting for a single trait (tameness), experimenters discovered that other traits of the animals were also changing unintentionally, giving them an appearance and temperament much closer to dogs, and very different from the wild foxes.

The experimenters selected for a single trait, low "flight distance" (the distance one can approach the animal before it runs away). Selecting this behavior mimics the natural selection that must have occurred in the ancestral past of dogs. Those with a low flight distance were the ones selected to breed the next generation. The changing traits of the animals that were "dragged along" as a result of selecting for low flight distance were completely unexpected by the experimenters.

Research Observations:
--The silver foxes began to show tame, doglike behaviours like whining to get attention, licking, tail-wagging, playfulness, and barking.
--They began to display floppy ears, shorter legs, shorter and curled tails and spotted fur.
--They began to show narrower skulls and shorter snouts than that of wild foxes.
--Females began to come into heat twice a year instead of just once as in the case of wild foxes.
--Tame fox puppies opened their eyes sooner and developed a fear response later than wild fox puppies.

An article on the experiment: suite101.com/article/domesticating-the-silver-fox-a68305

Scientific paper: www.hum.utah.edu/~bbenham/2510%20Spring%2009/Behavior%20Gene

And a much more detailed (and longer) explanation from AmericanScientist: https://www.americanscientist.org/issues/feature/early-canid

Wikipedia page on silver foxes: en.wikipedia.org/wiki/Domesticated_silver_fox

Dog domestication: www.dogspelledforward.com/evolution-of-the-dog/

Experimental Evolution: en.wikipedia.org/wiki/Experimental_evolution