Tame foxes offer a tantalizing window into the nature of domestication. Starting around 1960, Russian scientists took farm-bred foxes and began to breed them selectively, not for better fur, but for friendliness toward humans.
The result is a strain of foxes that appears to take just as much pleasure in the company of people as your average golden retriever. Their story was chronicled last year in a book whose co-author, Lyudmila N. Trut, is one of the scientists who conducted the experiment.
The tame foxes may seem like irresistible pets. But they are still nocturnal, not easily housebroken and not really well-suited to live in a house with human beings, said Anna V. Kukekova, of the University of Illinois, who studies the genetics of the foxes.
They are, however, an obvious resource for genetic studies that aim to tease out some of the genes involved in domestication, particularly in dogs. Foxes are canids, like wolves, dogs and the extinct wolves that are thought to have given rise to dogs.
Dr. Kukekova and a team of scientists in the United States, Russia and China, sequenced the red fox genome for the first time and then compared three strains of red foxes — farm bred, selected for tameness and selected for aggressiveness. All three strains were bred by the Institute of Cytology and Genetics of the Russian Academy of Sciences.
Dr. Kukekova and colleagues identified 103 regions of DNA that stood out as having been under selective pressure in the breeding, in which only the friendliest pups were allowed to mate. She also picked one gene that seemed to be a good candidate in selecting for tameness, called SorCS1. They reported their work in Nature Ecology & Evolution.
The gene is involved in regulating how the connections between brain cells work, which makes sense for a gene involved in social behavior. Other genes of interest are connected to human illnesses that affect behavior, like autism.
But determining how such genes might fit into domestication is a very complicated enterprise, Dr. Kukekova said. “The domestic dog is selected for so many different things,” she said. The fox is only selected for friendliness.
Bridgett vonHoldt, of Princeton University, recently reported that genes associated with Williams-Beuren syndrome in humans may be connected to why dogs are so friendly. She said the search for genes that affect behavior is very difficult. Even when genes are found that seem to be connected to behavior, she said, “We actually know very little about gene functions and the diversity of roles they actually play.”
Dr. Kukekova said that genes found in the fox are tantalizing hints. “We can’t be 100 percent sure that they are involved in the evolution of behavior.”
But the first step is to find these candidate genes, she said, and the current research shows that in that pursuit, the tame foxes are very useful animals.
Earlier science reporting on foxes