For thousands of years, dogs have been our companions. After countless generations of selective breeding, they've become hard-wired to follow human commands: sit, lie down, jump, even shake.
So far, most other animals don't come close. But what if they could?
In 1954 a Russian geneticist named Dmitry Belyaev wanted to isolate the genes that make dogs so easy to train. He started a fox farm in Siberia and set out to do with foxes in one lifetime what took dogs thousands of years.
Belyaev died in 1985, but others carried on his work; 50,000 foxes later, the project isn't complete, but it's close.
"So close. It's the last step," Ceiridwen Terrill tells weekends on All Things Considered host Guy Raz.
Terrill is associate professor of Science Writing and Environmental Journalism at Concordia University of Portland, Ore. She's also the author of Part Wild: One Woman's Journey with a Creature Caught Between the Worlds of Wolves and Dogs, a book about raising a dog-wolf hybrid.
Terrill recently visited Belyaev's fox farm, which she says looks like dilapidated army barracks.
"What you have are rows and rows of sheds that house about a hundred foxes each," she says. "There's about 3,000 foxes on-site."
Those foxes are so tame, Terrill was able to reach into one of the cages and give a fox a good belly-scratching.
"They're genetically designed to crave human contact," she says, "so that fox loved having its belly scratched."
Terrill says there are individual foxes who have been able to sit and fetch on command. But to prove true domestication, "it's really important that we see it on a large scale. It has to be in a systematic way," she adds.
"The experiment demonstrated that these foxes are indeed genetically tame," Terrill says. "Now what we don't know is if these foxes are truly domestic. And that can only be done by socialization and training. We won't know if that's possible unless foxes and humans are living together."
The experimental Siberian farm is selling fox cubs to allay its financial difficulties, but Terrill says they're not going to make good house pets.
"They promise that for just under $7,000, that you can get a fox on your front door that's four months old," she says. "Well, at four months old, the fox's socialization window has closed.
"They haven't been socialized to life in a human household in the way that a dog has, for example."
Better by far, Terrill says, to choose one of the many millions of dogs and cats who end up in American shelters every year.
"We have so many companion animals in desperate need of homes," she says.
Copyright 2012 National Public Radio. To see more, visit http://www.npr.org/.