The Dmitri Belyaev Experiment

In a time when Lysenkoism was official state doctrine, Belyaev's commitment to classical genetics had cost him his job as head of the Department of Fur Animal Breeding at the Central Research Laboratory of Fur Breeding in Moscow in 1948. During the 1950s, he continued to conduct genetic research under the guise of studying animal physiology. This was more acceptable to the Communist Party, which wanted to improve humans.

Belyaev believed that the key factor selected for domestication of dogs was not size or reproduction, but behavior; specifically amenability to domestication, or tameability. More than any other quality, Belyaev believed, tameability must have determined how well an animal would adapt to life among humans. Because behavior is rooted in biology, selecting for tameness and against aggression means selecting for physiological changes in the systems that govern the body's hormones and neurochemicals.

Belyaev decided to test his theory by domesticating foxes; in particular the Russian Silver Fox. He placed a population of them in the same process of domestication, and he decided to submit this population to a strong selection pressure for inherent tameness.

The result is that Russian scientists now have a number of tame foxes which are fundamentally different in temperament and behaviour from their wild forebears. Some important changes in physiology and morphology are now visible, such as mottled or spotted colored fur. Many scientists believe that these changes related to selecting for tameness are caused by lower adrenaline production in the new breed, which causes these physiological changes in a very small number of generations, thus allowing for these new genetic offshoots not present in the original species. Notably, the new foxes not only become more tame, but more dog-like as well: they lost their distinctive musky "fox smell", became more friendly with humans, put their ears down (like dogs), wagged their tails when happy and began to vocalize and bark like domesticated dogs.

The project also investigated breeding vicious foxes to study aggressive behavior. These foxes snap at humans and otherwise show no fear.