In a long-term experiment at a Siberian fur farm, geneticists created a new version of Vulpes vulpes, the silver fox, by allowing only the friendliest animals from each generation to breed. Having selected only the most ''tamable'' of some 45,000 foxes over 35 generations, the scientists have compressed into a mere 40 years an evolutionary process that took thousands of years to transform ancestral wolves into domestic dogs.

The original purpose of the breeding was to create a friendly breed less likely than wild animals to fight when put to death. But in time, geneticists saw that far-reaching changes they observed in the foxes' physical and neurological makeup merited scientific study. The scientists apparently underwent some changes, too. Close bonds developed between the tame foxes and their human wardens, and the staff at the fur farm is trying to find ways of saving the animals from slaughter.

The director of the experiment is Dr. Lyudmila N. Trut of the Institute of Cytology and Genetics of the Siberian Department of the Russian Academy of Sciences at Novosibirsk. She reported in a paper that selective breeding to create genetically docile animals had resulted in a breed of ultra-tame foxes that make good house pets ''as devoted as dogs but as independent as cats, capable of forming deep-rooted pair bonds with human beings.''