How Soviet Scientists Domesticated the Siberian Silver Fox

For millennia, dogs have lived side-by-side with humans. It took thousands of years to domesticate them. Cats have lived amongst humans for more than 4,000 years, but are still only considered semi-domesticated.

In stark contrast, it took only 35 years to domesticate the silver fox in Siberia. For the past 60 years, a team of Soviet geneticists has been conducting a groundbreaking experiment, offering us a real-time glimpse into the process of domestication.

In 1959, Soviet geneticist Dmitry Belyaev—director of the Institute of Cytology and Genetics of the U.S.S.R. (now Russian) Academy of Sciences in Novosibirsk—purchased 130 silver foxes from Soviet fur farms. His goal was to prove that the physical traits seen in domesticated animals—such as floppy ears and shorter snouts—could emerge simply by selecting for one behavior: friendliness toward humans.

The Experiment in Action

Rather than working with wolves, Belyaev chose silver foxes. He selectively bred only the tamest 20% of each generation, gradually producing foxes that became less fearful, more social, and increasingly dog-like in both behavior and appearance. 

Within just a few generations, these foxes showed significant physical changes: their ears drooped, their bodies became smaller, their tails curled, and even their skulls, jaws, and teeth were altered. These traits, common to other domesticated species, supported Darwin’s observation that “not a single domestic animal can be named which has not, in some country, drooping ears.”

To ensure these changes resulted from genetic selection rather than simple familiarity with humans, the foxes were never trained. They only had brief, controlled interactions with their caretakers. When the foxes reached sexual maturity, they were given a tameness score; only those that were least fearful and non-aggressive were allowed to breed.

The Legacy of the Soviet Experiment

After more than 40 generations, the result is a group of remarkably friendly, domesticated foxes. They eagerly approach humans, whimper to attract attention, sniff and lick their caretakers, and wag their tails when happy or excited. Their initial wariness of new stimuli has been replaced with curiosity and sociability. Recent genome mapping has even uncovered potential genetic link to tameness.

Despite near-collapse after the fall of the USSR—when funding dried up and the fox population dropped from 700 to just 100 as some were sold for fur—the experiment continues today. You can even support this ongoing research by purchasing one of these domesticated foxes as a pet for $9,000.